233-
THE FREQUENCY OF DEPRESSIVE SYMPTOMS IN A GENERAL POPULATION WITH REFERENCE TO DSM-III
EIRÍKUR LÍNDAL & JÓN G. STEFÁNSSON SUMMARY The frequency with which symptoms of depression are found among subjects with either a lifetime diagnosis of depression or dysthymia and among subjects with no
psychiatric disorders,
are
analysed.
The data is derived from a large study (n=862) on the lifetime prevalence of mental disorders which was conducted in Iceland. The survey instrument was the NIMH-Diagnostic Interview Schedule (DIS). Results from 379 subjects are reported in this study, these subjects have either experienced a Major Depressive Episode (n=46), dysthymia (n=32) or have no psychiatric disorder (n=301). The frequency of symptoms are grouped together in hierarchical tables and displayed and analysed. In the hierarchical groupings of symptoms, males were found to report more grave symptoms of suicide than were females, both in the depression and dysthymic groups. In a comorbidity correlation between these and other disorders, sex differences emerged in the diagnosis of Tobacco Dependence, with women exhibiting higher frequencies of dependence when found in the depressed group.
INTRODUCTION
Symptoms of illness are the main diagnostic indicators available to the clinician when making a psychiatric diagnosis. Specific symptoms are often seen as typical of a specific condition. Lists of symptoms are either constructed from clinical experience (Kaplan & Sadock, 1985) or from the application of systematic research methods of data collection (Comstock & Helsing, 1976). There is little literature on the distribution of symptoms among ’healthy’ subjects. In the present study we have limited ourselves to the analysis of depressive states. We examine not only the frequency of depressive symptoms as exhibited by subjects fulfilling DSM-III criteria for the diagnosis of major depression, but also the occurrence of these same symptoms among those with a Dim-111 diagnosis of dysthymia and among those with a negative history of a lifetime psychiatric diagnosis. Previous studies of symptom rates in large population samples have concentrated on the relationship between socioeconomic factors and diagnosis, but have not dealt specifically with the symptoms themselves (Comstock & Helsing, 1976; Eaton & Kessler,, 1981). In the publications from the large ECA study conducted in the USA (Eaton & Kessler, 1985) the rates of depression and of dysthymia are described but the prevalence of the symptoms themselves is not analysed. The differences in prevalence rates of depression found in other epidemiological surveys will not be addressed here, but an excellent review by Helgason (1990) on this topic has recently been published.
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
234
The selection criteria for diagnosing depression, dysthymia and for excluding the presence of psychiatric disorders among healthy individuals are derived from the Diagnostic and Statistical Manual for Mental Disorders, version III (APA, 1980). These classification categories have been incorporated into the National Institute of Mental Health’s Diagnostic Interview Schedule (DIS) (Robins & Helzer, 1985), which is an interview schedule originally developed for use in large scale epidemiological surveys in the USA (Robins et al. 1981; Eaton & Kessler, 1985; Eaton et cal. 1986). The DIS is used in this study to obtain reliable DSM-III diagnoses. In our analysis, we examine the frequency of depressive symptoms and make frequency comparisons between the depressed, the dysthymic and among those with a negative lifetime psychiatric diagnosis. In order to show a more complete picture of the differences, we look at the sex differences and the comorbidity of these subjects. The primary aim of our study was to construct frequency lists of depressive symptomatology comparing key symptoms between subjects meeting DSM-III diagnoses of major depression and dysthymia and those with a negative lifetime history of psychiatric disorder. SUBJECTS AND METHODS
Subjects The birth cohort material used in this study was derived from a large national epidemiological survey which was conducted in Iceland on the lifetime prevalence of mental disorders (Stefansson et al. 1990). The cohort was one half of the population (n =1195) born in the year 1931 and still living in Iceland on 1 st December 1986. Of these 1195 randomly selected subjects, 90 did not fulfil the criteria needed for inclusion in the study and 18 died prior to the interview. We were thus left with a selected list of 1087 possible candidates. After the completion of the survey, 46 subjects with a lifetime diagnosis of a major depressive episode and 32 with dysthymia were identified. Exclusion criteria were used with both diagnoses in order to make sure the subjects had only one affective diagnosis each. The number of subjects with no lifetime psychiatric diagnosis was 301. The data on these 379 cases served as our research material in the present study. The interviews with the subjects took place between March 1987 and March 1988. The subjects’ ages ranged from 55-57 years at that time. The participation rate was 79.3%. In all, 862 complete interviews were made. Because of Iceland’s small population (250,000), socioeconomic stratification is very vague and no comprehensive classification methods are known to be in common use. However, as the subjects in our study were randomly chosen and resided throughout the country, we may expect their status to be fairly uniform. With the health and welfare system being free for all subjects the likelihood of finding very poor people is limited, although economic status seems to have had an effect on the subjects in the Stirling County study (Murphy et al. 1991).
Method The research instrument was an Icelandic translation of the DIS (Stefánsson & Lindal, 1990). The DIS is a particularly interesting and practical survey instrument from an
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
235
epidemiological point of view. It can be used by non-clinically trained interviewers, who have only to have partaken in a 40 hour intensive training course. The course is conducted by clinicians who have been trained at the DIS training centre at Washington University, in St. Louis. The DIS takes a relatively short time to administer (60-90 min.), and covers 43 of the most common diagnoses in the DIM-111 (Robins et al. 1981). The survey data was checked and double entered by two different individuals into a computer, rechecked and analysed by a special DIS computer programme supplied by Washington University (Wu, 1985). The reliability of the DIS diagnosis compared to the DS1VI-III has been found to be good (Robins et al. 1982). Possible inconsistencies concerning past recollections in this type of lifetime prevalence study, as in all studies based on past events, can be attributed to recall error on behalf of the respondents rather than to the inexperience of the layinterviewers (McLeod et al. 1990). The use of well trained interviewers and of a standard structured interview are strong factors in minimizing possible effects of field-biases in the survey. The statistical methods used in the
following analyses were the chi-square test and (Ferguson, 1976). A significance level of < .O 1 was used as the level of a statistically significant difference, in line with the Bonferroni inequality method (Grove & Andreasen, 1982; Bailey, 1977) to lessen the chances of making a Type I error in multiple comparisons. Comparisons are made between subjects with DIS diagnoses of DIM-111 major depression (Group 1), DSM-III dysthymia (Group 2) and no psychiatric diagnosis (Group 3). Significant differences at the < .05 levels will be reported but referred Fisher’s Exact Test
to as tendencies in the results section.
RESULTS The
mean age for the onset of symptoms in Group 1 was 36.1 (SD 13.2) years and for Group 2, 35.9 (SD 11.4) years. The place of residence was urban in 27 cases (58%) in Group 1; in Group 2, urban in 211 cases (65%); and in Group 3, urban in 162 cases (5311/o). About half of the population of
Iceland resides in the capital and its nearby municipalities. The marital status of the subjects in the three groups is shown in Figure 1. The lifetime prevalence of the DSM-III/DIS diagnosis of major depressive episode (depression) was 2.9% among men (n = 13) and 7.8% among women (n = 33) aged 57-58 years (Table 1). For dysthymia the lifetime prevalence rates were 2.3 % for men (n 7) and 10.7% for women (n 25). The number of depressive subjects excluded because of having a coexisting dysthymia diagnosis was 23. The comorbidity of the subjects is shown in Table 1. The disorders most frequent among the general population are used here in the comorbidity analysis. Disorders not mentioned had too few individuals in them to allow for meaningful statistical =
=
comparisons. Alcoholic Abuse and Alcoholic Dependency. 1 (depressed) and 2 (dysthymic).
No differences were found between Groups
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
236
Figure 1. Marital Status: within
Phobic Disorder. Both men and of phobia significantly
diagnosis (p < .O1).
group
proportions
in Group 1 were found to have a lifetime often than did men and women in Group 2
women
more
Generalized Anxiety Disorder. Men in Group 1 had had generalized anxiety more often than had men in Group 2 (p < .O 1 ). Tobacco Dependency. Smokers were found most frequently in Group 1 for both men and women (p < .007 and p < .0002, respectively). In order to show the
frequency of depressive symptoms hierarchical symptom tables constructed. The symptom tables are comprehensive lists of the symptoms which are evaluated when diagnosing major depressive disorders according to DSM-III/DIS. were
In Table 2, the most common symptoms in Group I are shown alongside symptoms from Groups 2 and 3. When the frequencies of the most common symptoms in Group I are compared to the frequencies of these same symptoms as found in Group 2, we locate only three symptoms which are distinct for major depression. ’Concentration problems’, ’sex disinterest’ and feelings of ’guilt’ are commonly found in depression but rarely in dysthymia. Although tendencies were found in the cases of suicide attempts and suicidal thoughts (these did not reach the p < .O1 level and are thus not regarded as significant according to the Bonferroni inequality method). When the symptom frequencies in Group 1 are compared to those in Group 3, all symptoms are found to be significantly more common among the depressed. Most comparisons between Group 2 and Group 3 are also statistically significant. However, ’sex disinterest’ and ’hypersomnia’ are not found significantly more commonly among the dysthymics. Other significant differences were not noted in this table apart from rank displacements. The largest difference in rank displacement between depression and dysthymia was in the case of suicidal thoughts (16th place vs. 7th place). These thoughts rank higher among the dysthymics!
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
237 Table 1
Comorbidity of subjects with major depressive episode (group 1) and dysthymia (group 2). Comparisons are made between the ones having either of these diagnoses and those who do not have a psychiatric diagnosis (group 3). The percentages show the proportion of subjects of the same sex with the same diagnosis
The largest displacement in rank between the depressed and Group 3 was in the case of ’weight gain’, which was much higher in the rank table of Group 3 (5th place vs. 13th place). Of the five most common symptoms of depression, all except ’guilt’ are found in the top five symptoms in dysthymia and in Group 3 all are found except ’concentration problems’ and ’guilt’. In Table 3 are shown the five most common symptoms in each group. Separate lists are shown for the two sexes. In Group 1 the most striking difference is that males have ’suicidal thoughts’ whereas the females have only ’thoughts of death’. The same trend is found in the two sexes in Group 2. Males have the more serious symptom in their top five of having ’wanted to die’ and ’suicidal thoughts’ whereas the fema les have ’thoughts of death’. This division is not found in Group 3. DISCUSSION The lifetime
prevalence rate of major depression in our study was 5.3%. Similar lifetime prevalence rates have been found in other population studies where the DIS has been used
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
238
0
e
W) 500
Q&dquo; CU
0
1
f’1.U ...Ic .
-ux ji I;’;i ’A
:
W$I a : .s 11 5 §
r.f1
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
239 Table 3 The hierarchical frequency distribution of the five most each group for men and women
common
symptoms in
the survey instrument. In the ECA study conducted in the USA the prevalences between sites ranged from 4.2-5.2% (Robins et ccl. 1984); in Edmonton in Canada the rate was somewhat lower at 3.7(% (Bland, Orn & Newman, 1988). The prevalence in Puerto Rico was 4.7% (Canino et al. 1987). Our rates are higher than those in other DIS studies. The lifetime prevalence rate for dysthymia was 6.4% compared with USA rates ranging from 2.6-5.1 % (Robins et al. 1984), 3.7% in Edmonton (Bland, Orn & Newman, 1988) and 4.7% in Puerto Rico (Canino et rzl. 1987). As in the case of major depression this study identified a high rate of dysthymia. In the previous section it was noted that those who have experienced a severe depressive episode have reported distinct symptoms for this particular condition. These symptoms are almost non-existent in subjects who have had no psychiatric diagnosis, but become somewhat more common in those who have a lifetime diagnosis of dysthymia. Symptoms which seem to be more related to depressive episode than to other states of mind are: ’concentration difficulties’; ’guilt’; and ’sex disinterest’. Prevalences of these same symptoms from other studies where the DIS has not been used vary. For example, Winokur (1981) found ’concentration problems’ in 84% of hospitalised depressed patients but did not mention ’guilt’ and ’sex disinterest’ in his symptom list. However when the symptom list is broken down on the basis of sex (Table 3) we find that the list changes somewhat. Of the five most common depressive symptoms, the most significant change is in ’suicidal thoughts’. The contemplation of suicide is ranked third by men and seventh by women. There is a male preponderance among completed suicides in Iceland (Lunden, 1977). Men not only contemplate suicide more frequently than do women but also more commonly implement as
the act. We further find ’concentration troubles’ to be somewhat more common in males and ’guilt’ to be more common in women. It may also be noted that ’weight gain’ seems to be
exclusively the problem of women in this state. The issue of weight gain and weight loss has recently been researched by Stunkard et al. (1990). They found that the losing and
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
240
gaining of weight depended on the physical condition of the subject before the depressive episode. If s/he was fat, s/he tended to gain more weight, and if lean, to lose weight. Their data on the proportion of increase/decrease of weight are similar to our own although they do not divide their results according to sex. One of the aims of this study was to correlate the information gained from other sections of the DIS and explore the connection between the experience of a depressive episode and that of having another diagnosis or symptoms which might be of importance treating clinician. The high rates of phobic disorders are difficult to interpret as they behaviour when the depressive mood has set in. This naturally may also be the reflect may case with the high rates of psychosexual dysfunction that were encountered. In Table 2 we noted no significant rank differences in 11 out of 16 symptoms when comparing major depression to dysthymia. We further found that four out of five of the most common symptoms are the same in these groups. This similarity in the symptom profile does not make the task easier of acting on the clinical history as reported by the patient. The material suggests the existence of a very fine boundary between the condition to the
of major depression and dysthymia as presented in clinical descriptions. However, although overlap is considerable between the subject groups (including Group 3), ’guilt’ remains as a very significant symptom among those with major depression. This finding generates new questions which are outside the scope of the present study. These questions concern the effect of guilt on the ill subject’s mental state; its effect on the carrying out of suicide and on the ’suicidal depressive syndrome’ (Wolfersdorf et al. 1991); and on a possible illness evolution from dysthymia to major depression. It is our hope that our symptom list for a depressive episode will prove of use for clinicians who may perhaps not have the opportunity to carry out psychological tests but can evaluate and act accordingly based on the seriousness of the symptoms which the patient reveals to them. ACKNOWLEDGEMENTS
This study Fund and
was
by
supported by the Icelandic Science Foundation, the University Science Department of Psychiatry at the National University Hospital in
the
Reykjavik. REFERENCES AMERICAN PSYCHIATRIC ASSOCIATION (1980) Diagnostic and Statistical Manual of Mental Disorders. 3rd Ed. Washington, D.C. BAILEY, B.J.R. (1977) Tables of the Bonferronitstatistic. Journal of the American Statistical Association, 469478. BLAND, R.C., ORN, H. & NEWMAN, S.C. (1988) Lifetime prevalence of psychiatric disorders in Edmonton. Acta Psychiatrica Scandinavica, 77, Suppl. 338, 24-32. COMSTOCK, G.W. & HELSING, K.J. (1976) Symptoms of depression in two communities. Psychological
Medicine, 6, 551-563. CANINO, G.J., BIRD, H.R., SHROUT, P.E., RUBIO-STIPEC, M., BRAVO, M., MARTINEZ, R., SESMAN, M. & GUEVARA, L.M. (1987) The prevalence of specific psychiatric disorders in Puerto Rico. Archives of General Psychiatry, 44, 727-735.
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
241 W.W. & KESSLER, L.G. (1981) Rates of symptoms of depression in a national sample. American Journal of Epidemiology, 114, 528-538. EATON, W.W. & KESSLER, L.G. (1985) (eds.) Epidemiologic Field Methods in Psychiatry: the NIMH Epidemiologic Catchment Area Program. Orlando: Academic Press. EATON, W.W., REGIER, D.A., LOCKE, B.Z. & TAUBE, C.A. (1986) The NIMH epidemiologic catchment area program. In Community Surveys of Psychiatric Disorders (eds M.M. Weissmann, J.K. Myers & C.E. Ross). New Brunswick: Rutgers Univ. Press, 209-219. FERGUSON, G.A. (1976) Statistical Analysis in Psychology and Education, 4th ed. New York: McGraw-Hill. GROVE, W.M. & ANDREASEN, N.C. (1982) Simultaneous tests of many hypotheses in exploratory research. Journal of Nervous and Mental Disease, 170, 3-8. HELGASON, T. (1990) The epidemiology of depression (Danish). Nordisk Psykiatrivk Tidsskrift, 44, 3-12. KAPLAN, H.I. & SADOCK, B.J. (1985) Comprehensive Textbook of Psychiatry. London: Williams & Wilkins, 896-901. LUNDEN, W.A. (1977) The Suicide Cycle. Iowa: Sutherland Printing Co., 131-134. J.M. (1990) Sources of discrepancy in the McLEOD, J.D., TURNBULL, J.E., KESSLER, R.C. & ABELSON, comparison of a lay-administered diagnostic instrument with clinical diagnosis. Psychiatry Research, 31, 145-159.
EATON,
MURPHY, J.M., OLIVIER, D.C., MONSON, R.R., SOBOL, A.M., FEDERMAN, E.B. & LEIGHTON, A.H. (1991) Depression and anxiety in relation to social status. A prospective epidemiological study. Archives of General Psychiatry, 48, 223-229. ROBINS, L.N., HELZER, J.E., CROUGHAN, J. & RATCLIFF, K.S. (1981) The National Institute of Mental Health Diagnostic Interview Schedule. Archives of General Psychiatry, 38, 381-389. ROBINS, L.N., HELZER, J.E., RATCLIFF, K.S. & SEYFRIED, W.(1982) Validity of the Diagnostic Interview Schedule, version II: DSM-III diagnoses. Psychological Medicine, 12, 855-870. ROBINS, L.N., HELZER, J.E., WEISSMAN, M.M., ORVASCHEL, H., GRUENBERG, E., BURKE, J.D. & REGIER, D.A. (1984) Lifetime prevalence of specific psychiatric disorders in three sites. Archives of General Psychiatry, 41, 949-958. ROBINS, L.N. & HELZER, J.E. (1985) The NIMH-Diagnostic Interview Schedule, Version IIIA. Department of Psychiatry, Washington University School of Medicine, St. Louis. STEFÁNSSON, J.G. & LINDAL, E.L. (1990) Greinigarviotal (DIS IIIA) (Icelandic). Reykjavik: University of Iceland Publications.
STEFÁNSSON, J.G., LINDAL,
E.L., BJÖRNSSON, J.K. & GUDMUNDSDÓTTIR, Á. (1991). Lifetime prevalence of specific mental disorders among persons born in Iceland in 1931. Acta Psychiatrica , 142-149. 84 Scandinavica, STUNKARD, A.J., FERNSTROM, M., PRICE, A., FRANK, E. & KUPFER, D.J. (1990) Direction of weight change in recurrent depression. Archives of General Psychiatry, 47, 857-860. WASHINGTON UNIVERSITY (1985) SAS Diagnostic Program for the scoring of the NIMH-DIS [Computer Program]. Washington University School of Medicine, Department of Psychiatry, St. Louis. WINOKUR, G. (1981) Depression. Oxford: Oxford University Press. WOLFERSDORF, M., HOLE, G., STEINER, B. & KELLER, F. (1990) Suicidal risk in suicidal versus nonsuicidal depressed inpatients. Crisis, 11, 85-97.
Eirikur Jón G.
Lindal, Department of Psychiatry, National University Hospital, 101 Reykjavik, Iceland. Stefánsson, Department of Psychiatry, National University Hospital,101Reyjkavík, Iceland.
Correspondence
to Dr.
Lindal
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
THE FREQUENCY OF DEPRESSIVE SYMPTOMS IN A GENERAL POPULATION WITH REFERENCE TO DSM-III
EIRÍKUR LÍNDAL & JÓN G. STEFÁNSSON SUMMARY The frequency with which symptoms of depression are found among subjects with either a lifetime diagnosis of depression or dysthymia and among subjects with no
psychiatric disorders,
are
analysed.
The data is derived from a large study (n=862) on the lifetime prevalence of mental disorders which was conducted in Iceland. The survey instrument was the NIMH-Diagnostic Interview Schedule (DIS). Results from 379 subjects are reported in this study, these subjects have either experienced a Major Depressive Episode (n=46), dysthymia (n=32) or have no psychiatric disorder (n=301). The frequency of symptoms are grouped together in hierarchical tables and displayed and analysed. In the hierarchical groupings of symptoms, males were found to report more grave symptoms of suicide than were females, both in the depression and dysthymic groups. In a comorbidity correlation between these and other disorders, sex differences emerged in the diagnosis of Tobacco Dependence, with women exhibiting higher frequencies of dependence when found in the depressed group.
INTRODUCTION
Symptoms of illness are the main diagnostic indicators available to the clinician when making a psychiatric diagnosis. Specific symptoms are often seen as typical of a specific condition. Lists of symptoms are either constructed from clinical experience (Kaplan & Sadock, 1985) or from the application of systematic research methods of data collection (Comstock & Helsing, 1976). There is little literature on the distribution of symptoms among ’healthy’ subjects. In the present study we have limited ourselves to the analysis of depressive states. We examine not only the frequency of depressive symptoms as exhibited by subjects fulfilling DSM-III criteria for the diagnosis of major depression, but also the occurrence of these same symptoms among those with a Dim-111 diagnosis of dysthymia and among those with a negative history of a lifetime psychiatric diagnosis. Previous studies of symptom rates in large population samples have concentrated on the relationship between socioeconomic factors and diagnosis, but have not dealt specifically with the symptoms themselves (Comstock & Helsing, 1976; Eaton & Kessler,, 1981). In the publications from the large ECA study conducted in the USA (Eaton & Kessler, 1985) the rates of depression and of dysthymia are described but the prevalence of the symptoms themselves is not analysed. The differences in prevalence rates of depression found in other epidemiological surveys will not be addressed here, but an excellent review by Helgason (1990) on this topic has recently been published.
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
234
The selection criteria for diagnosing depression, dysthymia and for excluding the presence of psychiatric disorders among healthy individuals are derived from the Diagnostic and Statistical Manual for Mental Disorders, version III (APA, 1980). These classification categories have been incorporated into the National Institute of Mental Health’s Diagnostic Interview Schedule (DIS) (Robins & Helzer, 1985), which is an interview schedule originally developed for use in large scale epidemiological surveys in the USA (Robins et al. 1981; Eaton & Kessler, 1985; Eaton et cal. 1986). The DIS is used in this study to obtain reliable DSM-III diagnoses. In our analysis, we examine the frequency of depressive symptoms and make frequency comparisons between the depressed, the dysthymic and among those with a negative lifetime psychiatric diagnosis. In order to show a more complete picture of the differences, we look at the sex differences and the comorbidity of these subjects. The primary aim of our study was to construct frequency lists of depressive symptomatology comparing key symptoms between subjects meeting DSM-III diagnoses of major depression and dysthymia and those with a negative lifetime history of psychiatric disorder. SUBJECTS AND METHODS
Subjects The birth cohort material used in this study was derived from a large national epidemiological survey which was conducted in Iceland on the lifetime prevalence of mental disorders (Stefansson et al. 1990). The cohort was one half of the population (n =1195) born in the year 1931 and still living in Iceland on 1 st December 1986. Of these 1195 randomly selected subjects, 90 did not fulfil the criteria needed for inclusion in the study and 18 died prior to the interview. We were thus left with a selected list of 1087 possible candidates. After the completion of the survey, 46 subjects with a lifetime diagnosis of a major depressive episode and 32 with dysthymia were identified. Exclusion criteria were used with both diagnoses in order to make sure the subjects had only one affective diagnosis each. The number of subjects with no lifetime psychiatric diagnosis was 301. The data on these 379 cases served as our research material in the present study. The interviews with the subjects took place between March 1987 and March 1988. The subjects’ ages ranged from 55-57 years at that time. The participation rate was 79.3%. In all, 862 complete interviews were made. Because of Iceland’s small population (250,000), socioeconomic stratification is very vague and no comprehensive classification methods are known to be in common use. However, as the subjects in our study were randomly chosen and resided throughout the country, we may expect their status to be fairly uniform. With the health and welfare system being free for all subjects the likelihood of finding very poor people is limited, although economic status seems to have had an effect on the subjects in the Stirling County study (Murphy et al. 1991).
Method The research instrument was an Icelandic translation of the DIS (Stefánsson & Lindal, 1990). The DIS is a particularly interesting and practical survey instrument from an
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
235
epidemiological point of view. It can be used by non-clinically trained interviewers, who have only to have partaken in a 40 hour intensive training course. The course is conducted by clinicians who have been trained at the DIS training centre at Washington University, in St. Louis. The DIS takes a relatively short time to administer (60-90 min.), and covers 43 of the most common diagnoses in the DIM-111 (Robins et al. 1981). The survey data was checked and double entered by two different individuals into a computer, rechecked and analysed by a special DIS computer programme supplied by Washington University (Wu, 1985). The reliability of the DIS diagnosis compared to the DS1VI-III has been found to be good (Robins et al. 1982). Possible inconsistencies concerning past recollections in this type of lifetime prevalence study, as in all studies based on past events, can be attributed to recall error on behalf of the respondents rather than to the inexperience of the layinterviewers (McLeod et al. 1990). The use of well trained interviewers and of a standard structured interview are strong factors in minimizing possible effects of field-biases in the survey. The statistical methods used in the
following analyses were the chi-square test and (Ferguson, 1976). A significance level of < .O 1 was used as the level of a statistically significant difference, in line with the Bonferroni inequality method (Grove & Andreasen, 1982; Bailey, 1977) to lessen the chances of making a Type I error in multiple comparisons. Comparisons are made between subjects with DIS diagnoses of DIM-111 major depression (Group 1), DSM-III dysthymia (Group 2) and no psychiatric diagnosis (Group 3). Significant differences at the < .05 levels will be reported but referred Fisher’s Exact Test
to as tendencies in the results section.
RESULTS The
mean age for the onset of symptoms in Group 1 was 36.1 (SD 13.2) years and for Group 2, 35.9 (SD 11.4) years. The place of residence was urban in 27 cases (58%) in Group 1; in Group 2, urban in 211 cases (65%); and in Group 3, urban in 162 cases (5311/o). About half of the population of
Iceland resides in the capital and its nearby municipalities. The marital status of the subjects in the three groups is shown in Figure 1. The lifetime prevalence of the DSM-III/DIS diagnosis of major depressive episode (depression) was 2.9% among men (n = 13) and 7.8% among women (n = 33) aged 57-58 years (Table 1). For dysthymia the lifetime prevalence rates were 2.3 % for men (n 7) and 10.7% for women (n 25). The number of depressive subjects excluded because of having a coexisting dysthymia diagnosis was 23. The comorbidity of the subjects is shown in Table 1. The disorders most frequent among the general population are used here in the comorbidity analysis. Disorders not mentioned had too few individuals in them to allow for meaningful statistical =
=
comparisons. Alcoholic Abuse and Alcoholic Dependency. 1 (depressed) and 2 (dysthymic).
No differences were found between Groups
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
236
Figure 1. Marital Status: within
Phobic Disorder. Both men and of phobia significantly
diagnosis (p < .O1).
group
proportions
in Group 1 were found to have a lifetime often than did men and women in Group 2
women
more
Generalized Anxiety Disorder. Men in Group 1 had had generalized anxiety more often than had men in Group 2 (p < .O 1 ). Tobacco Dependency. Smokers were found most frequently in Group 1 for both men and women (p < .007 and p < .0002, respectively). In order to show the
frequency of depressive symptoms hierarchical symptom tables constructed. The symptom tables are comprehensive lists of the symptoms which are evaluated when diagnosing major depressive disorders according to DSM-III/DIS. were
In Table 2, the most common symptoms in Group I are shown alongside symptoms from Groups 2 and 3. When the frequencies of the most common symptoms in Group I are compared to the frequencies of these same symptoms as found in Group 2, we locate only three symptoms which are distinct for major depression. ’Concentration problems’, ’sex disinterest’ and feelings of ’guilt’ are commonly found in depression but rarely in dysthymia. Although tendencies were found in the cases of suicide attempts and suicidal thoughts (these did not reach the p < .O1 level and are thus not regarded as significant according to the Bonferroni inequality method). When the symptom frequencies in Group 1 are compared to those in Group 3, all symptoms are found to be significantly more common among the depressed. Most comparisons between Group 2 and Group 3 are also statistically significant. However, ’sex disinterest’ and ’hypersomnia’ are not found significantly more commonly among the dysthymics. Other significant differences were not noted in this table apart from rank displacements. The largest difference in rank displacement between depression and dysthymia was in the case of suicidal thoughts (16th place vs. 7th place). These thoughts rank higher among the dysthymics!
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
237 Table 1
Comorbidity of subjects with major depressive episode (group 1) and dysthymia (group 2). Comparisons are made between the ones having either of these diagnoses and those who do not have a psychiatric diagnosis (group 3). The percentages show the proportion of subjects of the same sex with the same diagnosis
The largest displacement in rank between the depressed and Group 3 was in the case of ’weight gain’, which was much higher in the rank table of Group 3 (5th place vs. 13th place). Of the five most common symptoms of depression, all except ’guilt’ are found in the top five symptoms in dysthymia and in Group 3 all are found except ’concentration problems’ and ’guilt’. In Table 3 are shown the five most common symptoms in each group. Separate lists are shown for the two sexes. In Group 1 the most striking difference is that males have ’suicidal thoughts’ whereas the females have only ’thoughts of death’. The same trend is found in the two sexes in Group 2. Males have the more serious symptom in their top five of having ’wanted to die’ and ’suicidal thoughts’ whereas the fema les have ’thoughts of death’. This division is not found in Group 3. DISCUSSION The lifetime
prevalence rate of major depression in our study was 5.3%. Similar lifetime prevalence rates have been found in other population studies where the DIS has been used
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
238
0
e
W) 500
Q&dquo; CU
0
1
f’1.U ...Ic .
-ux ji I;’;i ’A
:
W$I a : .s 11 5 §
r.f1
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
239 Table 3 The hierarchical frequency distribution of the five most each group for men and women
common
symptoms in
the survey instrument. In the ECA study conducted in the USA the prevalences between sites ranged from 4.2-5.2% (Robins et ccl. 1984); in Edmonton in Canada the rate was somewhat lower at 3.7(% (Bland, Orn & Newman, 1988). The prevalence in Puerto Rico was 4.7% (Canino et al. 1987). Our rates are higher than those in other DIS studies. The lifetime prevalence rate for dysthymia was 6.4% compared with USA rates ranging from 2.6-5.1 % (Robins et al. 1984), 3.7% in Edmonton (Bland, Orn & Newman, 1988) and 4.7% in Puerto Rico (Canino et rzl. 1987). As in the case of major depression this study identified a high rate of dysthymia. In the previous section it was noted that those who have experienced a severe depressive episode have reported distinct symptoms for this particular condition. These symptoms are almost non-existent in subjects who have had no psychiatric diagnosis, but become somewhat more common in those who have a lifetime diagnosis of dysthymia. Symptoms which seem to be more related to depressive episode than to other states of mind are: ’concentration difficulties’; ’guilt’; and ’sex disinterest’. Prevalences of these same symptoms from other studies where the DIS has not been used vary. For example, Winokur (1981) found ’concentration problems’ in 84% of hospitalised depressed patients but did not mention ’guilt’ and ’sex disinterest’ in his symptom list. However when the symptom list is broken down on the basis of sex (Table 3) we find that the list changes somewhat. Of the five most common depressive symptoms, the most significant change is in ’suicidal thoughts’. The contemplation of suicide is ranked third by men and seventh by women. There is a male preponderance among completed suicides in Iceland (Lunden, 1977). Men not only contemplate suicide more frequently than do women but also more commonly implement as
the act. We further find ’concentration troubles’ to be somewhat more common in males and ’guilt’ to be more common in women. It may also be noted that ’weight gain’ seems to be
exclusively the problem of women in this state. The issue of weight gain and weight loss has recently been researched by Stunkard et al. (1990). They found that the losing and
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
240
gaining of weight depended on the physical condition of the subject before the depressive episode. If s/he was fat, s/he tended to gain more weight, and if lean, to lose weight. Their data on the proportion of increase/decrease of weight are similar to our own although they do not divide their results according to sex. One of the aims of this study was to correlate the information gained from other sections of the DIS and explore the connection between the experience of a depressive episode and that of having another diagnosis or symptoms which might be of importance treating clinician. The high rates of phobic disorders are difficult to interpret as they behaviour when the depressive mood has set in. This naturally may also be the reflect may case with the high rates of psychosexual dysfunction that were encountered. In Table 2 we noted no significant rank differences in 11 out of 16 symptoms when comparing major depression to dysthymia. We further found that four out of five of the most common symptoms are the same in these groups. This similarity in the symptom profile does not make the task easier of acting on the clinical history as reported by the patient. The material suggests the existence of a very fine boundary between the condition to the
of major depression and dysthymia as presented in clinical descriptions. However, although overlap is considerable between the subject groups (including Group 3), ’guilt’ remains as a very significant symptom among those with major depression. This finding generates new questions which are outside the scope of the present study. These questions concern the effect of guilt on the ill subject’s mental state; its effect on the carrying out of suicide and on the ’suicidal depressive syndrome’ (Wolfersdorf et al. 1991); and on a possible illness evolution from dysthymia to major depression. It is our hope that our symptom list for a depressive episode will prove of use for clinicians who may perhaps not have the opportunity to carry out psychological tests but can evaluate and act accordingly based on the seriousness of the symptoms which the patient reveals to them. ACKNOWLEDGEMENTS
This study Fund and
was
by
supported by the Icelandic Science Foundation, the University Science Department of Psychiatry at the National University Hospital in
the
Reykjavik. REFERENCES AMERICAN PSYCHIATRIC ASSOCIATION (1980) Diagnostic and Statistical Manual of Mental Disorders. 3rd Ed. Washington, D.C. BAILEY, B.J.R. (1977) Tables of the Bonferronitstatistic. Journal of the American Statistical Association, 469478. BLAND, R.C., ORN, H. & NEWMAN, S.C. (1988) Lifetime prevalence of psychiatric disorders in Edmonton. Acta Psychiatrica Scandinavica, 77, Suppl. 338, 24-32. COMSTOCK, G.W. & HELSING, K.J. (1976) Symptoms of depression in two communities. Psychological
Medicine, 6, 551-563. CANINO, G.J., BIRD, H.R., SHROUT, P.E., RUBIO-STIPEC, M., BRAVO, M., MARTINEZ, R., SESMAN, M. & GUEVARA, L.M. (1987) The prevalence of specific psychiatric disorders in Puerto Rico. Archives of General Psychiatry, 44, 727-735.
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
241 W.W. & KESSLER, L.G. (1981) Rates of symptoms of depression in a national sample. American Journal of Epidemiology, 114, 528-538. EATON, W.W. & KESSLER, L.G. (1985) (eds.) Epidemiologic Field Methods in Psychiatry: the NIMH Epidemiologic Catchment Area Program. Orlando: Academic Press. EATON, W.W., REGIER, D.A., LOCKE, B.Z. & TAUBE, C.A. (1986) The NIMH epidemiologic catchment area program. In Community Surveys of Psychiatric Disorders (eds M.M. Weissmann, J.K. Myers & C.E. Ross). New Brunswick: Rutgers Univ. Press, 209-219. FERGUSON, G.A. (1976) Statistical Analysis in Psychology and Education, 4th ed. New York: McGraw-Hill. GROVE, W.M. & ANDREASEN, N.C. (1982) Simultaneous tests of many hypotheses in exploratory research. Journal of Nervous and Mental Disease, 170, 3-8. HELGASON, T. (1990) The epidemiology of depression (Danish). Nordisk Psykiatrivk Tidsskrift, 44, 3-12. KAPLAN, H.I. & SADOCK, B.J. (1985) Comprehensive Textbook of Psychiatry. London: Williams & Wilkins, 896-901. LUNDEN, W.A. (1977) The Suicide Cycle. Iowa: Sutherland Printing Co., 131-134. J.M. (1990) Sources of discrepancy in the McLEOD, J.D., TURNBULL, J.E., KESSLER, R.C. & ABELSON, comparison of a lay-administered diagnostic instrument with clinical diagnosis. Psychiatry Research, 31, 145-159.
EATON,
MURPHY, J.M., OLIVIER, D.C., MONSON, R.R., SOBOL, A.M., FEDERMAN, E.B. & LEIGHTON, A.H. (1991) Depression and anxiety in relation to social status. A prospective epidemiological study. Archives of General Psychiatry, 48, 223-229. ROBINS, L.N., HELZER, J.E., CROUGHAN, J. & RATCLIFF, K.S. (1981) The National Institute of Mental Health Diagnostic Interview Schedule. Archives of General Psychiatry, 38, 381-389. ROBINS, L.N., HELZER, J.E., RATCLIFF, K.S. & SEYFRIED, W.(1982) Validity of the Diagnostic Interview Schedule, version II: DSM-III diagnoses. Psychological Medicine, 12, 855-870. ROBINS, L.N., HELZER, J.E., WEISSMAN, M.M., ORVASCHEL, H., GRUENBERG, E., BURKE, J.D. & REGIER, D.A. (1984) Lifetime prevalence of specific psychiatric disorders in three sites. Archives of General Psychiatry, 41, 949-958. ROBINS, L.N. & HELZER, J.E. (1985) The NIMH-Diagnostic Interview Schedule, Version IIIA. Department of Psychiatry, Washington University School of Medicine, St. Louis. STEFÁNSSON, J.G. & LINDAL, E.L. (1990) Greinigarviotal (DIS IIIA) (Icelandic). Reykjavik: University of Iceland Publications.
STEFÁNSSON, J.G., LINDAL,
E.L., BJÖRNSSON, J.K. & GUDMUNDSDÓTTIR, Á. (1991). Lifetime prevalence of specific mental disorders among persons born in Iceland in 1931. Acta Psychiatrica , 142-149. 84 Scandinavica, STUNKARD, A.J., FERNSTROM, M., PRICE, A., FRANK, E. & KUPFER, D.J. (1990) Direction of weight change in recurrent depression. Archives of General Psychiatry, 47, 857-860. WASHINGTON UNIVERSITY (1985) SAS Diagnostic Program for the scoring of the NIMH-DIS [Computer Program]. Washington University School of Medicine, Department of Psychiatry, St. Louis. WINOKUR, G. (1981) Depression. Oxford: Oxford University Press. WOLFERSDORF, M., HOLE, G., STEINER, B. & KELLER, F. (1990) Suicidal risk in suicidal versus nonsuicidal depressed inpatients. Crisis, 11, 85-97.
Eirikur Jón G.
Lindal, Department of Psychiatry, National University Hospital, 101 Reykjavik, Iceland. Stefánsson, Department of Psychiatry, National University Hospital,101Reyjkavík, Iceland.
Correspondence
to Dr.
Lindal
Downloaded from isp.sagepub.com at Freie Universitaet Berlin on May 10, 2015
