RESEARCH INTO PSYCHIATRIC DISORDER AFTER STROKE: THE NEED FOR FURTHER STUDIES G . A. Johnson
Attention is drawn to some shortcomings of previous findings with regard to the nature, prevalence and aetiology of psychiatric disorder after stroke, and in particular post-stroke depression. Reasons for and drawbacks of the emphasis on depression in studies to date are discussed. Inconsistencies amongst previous findings are examined and it is suggested that many further studies in the area are warranted providing methodological difficulties are addressed adequately. Australian and New Zealand Journal of Psychiatry 1991;25:358-370 Over the past ten years there has been a growing literature on the psychiatric sequelae of stroke. However findings to date have been inconsistent, the focus has been narrow and conclusions may have been premature. This paper draws attention to various unsatisfactory aspects of previous research into poststroke psychiatric disorder. Areas discussed include an excessive emphasis on depression and an associated failure to look adequately for other psychiatric sequelae of stroke. In addition the limitations of data which has been collected on prevalence and aetiology of post-stroke depression are pointed out, given that many studies have examined only small numbers of subjects or special subgroups and insufficient or inappropriate measures have sometimes been applied. The recycling of data on some subject groups and the incomparability of groups examined in different studies makes it very difficult to assess the relative strengths of different findings. Clear conclusions do not emerge at this stage and further research in the area is indicated.
Department of Psychiatry and Behavioural Science, University of Western Australia G. A. Johnson, MB ChB, FRANZCP
The emphasis on depression A cursory consideration of the nature of stroke and aetiological factors relevant to psychiatric disorder in general suggest that stroke patients should be at increased risk of a range of psychiatric disorders. Nonetheless, whilst there have been case reports suggesting that stroke can result in a variety of psychiatric syndromes [ 1-91 there has been little systematic examination of the incidence of syndromes other than depression. The notion that post-stroke depression in particular is an important entity seems to have become widely accepted. Earlier there were sporadic reports of cases of severe depression after stroke and of a high incidence of cerebrovascular disease amongst elderly patients with depression [ 10-161. Since 1979 more systematic studies of the incidence, nature, aetiology and treatment of post-stroke depression have been made [ 17-33]. These have generally been taken to indicate that people who have had strokes are at increased risk of depression, that this depression is serious but infrequently diagnosed and inadequately treated in clinical practice, and that it is important to address this 17-20,22,25,28,34-361. However, these
G . A. JOHNSON
Table I. Reported point prevalence rates for depression six months post-stroke
Feibel & Springer [19]) N=91 Robinson et al [22] N=50 Ebrahim et al [26] N=i 49 Wade [28] N=337 House 129) N=l28
All cases of depression including “mild”, “minor”, “probable”
Cases of “severe”, “major” or “definite” depression only
Oh
%
26 60
34
46
23
32
20
32
13
conclusions may be premature and in need of substan tial qualification for a variety of reasons. The striking concentration on depression in studies of stroke patients so far probably has its origins in a number of factors. Depression does with particular force elicit concerned responses in others - in fact this is one of the social functions of depression. Carers, including physicians and other professional staff, may be especially likely to want to do something for the patient who displays depressive features and psychiatric referral may be more likely on the basis of depressive than anxiety symptoms, for example. This may explain the early case reports of depression in stroke patients which stimulated research on poststroke depression. Subsequent systematic studies of stroke patients almost exclusively focussed on hospitalised cases and patients in rehabilitation programmes and therefore were biased towards inclusion of patients with more severe initial strokes and more persistent disabilities, factors likely to have promoted depression. Depression is also generally liable to become chronic and treatment-resistant in the elderly [37,38]. This not only increases its prominence but also stimulates interest in its aetiology and nature, particularly given the existence of effective treatments for depression in younger patients. Stroke patients are relatively common and as a group provide the opportunity for
359
examination of a variety of aetiological hypotheses about depression in the elderly. Depression may also be simpler to measure than some other psychiatric disorders. Despite ongoing controversies about the nosological status of subtypes o i depressive disorder, there is a plethora of respectable instruments for assessing the presence and severity of nonspecific “depression” and relating it to certain depressive disorders. Most require only assessment of a patient’s symptoms at a specific point in time, rather than longitudinal study, and they are therefore easy and quick to use. By contrast, for example, the lack of equally simple, reliable and validated instruments for assessment of personality, especially in the elderly, has presumably made researchers defer looking for personality change as a function of stroke, despite suggestions that organic personality syndromes may be common and troublesome [36,39]. Other disorders may also masquerade as depression. Many of the symptoms and signs of depression are relatively non-specific and patients with other psychiatric and physical disorders may achieve inflated scores on instruments used to assess depression [40, 41 1. This in turn may lead to over-estimation of the frequency and severity of depression unless other disorders are taken into account. Symptom scores should not be transformed into diagnoses in these patients unless cut-off scores established for use in physically ill patients are used and rigorous diagnostic criteria, including exclusion criteria, are applied. This has not always been done. Scales which only rate severity of depression should not be applied to subjects who do not actually fulfil criteria for a diagnosis of depression. There is a common practice [ 18, 20, 21, 25, 28, 331 of simply using “depression” scores from all subjects, whether depressed or not, on instruments such as the Hamilton Rating Scale for Depression, to examine correlations between post-stroke depression and other factors such as disability; this is of questionable validity, especially when the “depression” scores may be heavily loaded in some patients by physical symptoms not due to depression. It has been suggested that criteria for diagnosis of depression in stroke patients should actually be quite different from those used normally, because neurological signs may both mask and mimic depression (41, 421. The disturbances in motor behaviour, facial expression, verbal communication and cognition which accompany strokes make use of standard assessment instruments difficult as well as raising
RESEARCH INTO PSYCHIATRIC DISORDER AFTER STROKE
360
Table 2. Reported associations hetH,eenpost-stroke deprrssioii mid physicul disubility ~
Time since stroke
Association between depression and physical disability
N
Source of subjects
Robinson and Szetela [ 181
29
Acute hospital
6 - 12 months
No
Feibel and Springer [19]
91
Acute hospital
6 months
No
Robinson and Price [20]
30
Outpatient clinic
Attention is drawn to some shortcomings of previous findings with regard to the nature, prevalence and aetiology of psychiatric disorder after stroke, and in particular post-stroke depression. Reasons for and drawbacks of the emphasis on depression in studies to date are discussed. Inconsistencies amongst previous findings are examined and it is suggested that many further studies in the area are warranted providing methodological difficulties are addressed adequately. Australian and New Zealand Journal of Psychiatry 1991;25:358-370 Over the past ten years there has been a growing literature on the psychiatric sequelae of stroke. However findings to date have been inconsistent, the focus has been narrow and conclusions may have been premature. This paper draws attention to various unsatisfactory aspects of previous research into poststroke psychiatric disorder. Areas discussed include an excessive emphasis on depression and an associated failure to look adequately for other psychiatric sequelae of stroke. In addition the limitations of data which has been collected on prevalence and aetiology of post-stroke depression are pointed out, given that many studies have examined only small numbers of subjects or special subgroups and insufficient or inappropriate measures have sometimes been applied. The recycling of data on some subject groups and the incomparability of groups examined in different studies makes it very difficult to assess the relative strengths of different findings. Clear conclusions do not emerge at this stage and further research in the area is indicated.
Department of Psychiatry and Behavioural Science, University of Western Australia G. A. Johnson, MB ChB, FRANZCP
The emphasis on depression A cursory consideration of the nature of stroke and aetiological factors relevant to psychiatric disorder in general suggest that stroke patients should be at increased risk of a range of psychiatric disorders. Nonetheless, whilst there have been case reports suggesting that stroke can result in a variety of psychiatric syndromes [ 1-91 there has been little systematic examination of the incidence of syndromes other than depression. The notion that post-stroke depression in particular is an important entity seems to have become widely accepted. Earlier there were sporadic reports of cases of severe depression after stroke and of a high incidence of cerebrovascular disease amongst elderly patients with depression [ 10-161. Since 1979 more systematic studies of the incidence, nature, aetiology and treatment of post-stroke depression have been made [ 17-33]. These have generally been taken to indicate that people who have had strokes are at increased risk of depression, that this depression is serious but infrequently diagnosed and inadequately treated in clinical practice, and that it is important to address this 17-20,22,25,28,34-361. However, these
G . A. JOHNSON
Table I. Reported point prevalence rates for depression six months post-stroke
Feibel & Springer [19]) N=91 Robinson et al [22] N=50 Ebrahim et al [26] N=i 49 Wade [28] N=337 House 129) N=l28
All cases of depression including “mild”, “minor”, “probable”
Cases of “severe”, “major” or “definite” depression only
Oh
%
26 60
34
46
23
32
20
32
13
conclusions may be premature and in need of substan tial qualification for a variety of reasons. The striking concentration on depression in studies of stroke patients so far probably has its origins in a number of factors. Depression does with particular force elicit concerned responses in others - in fact this is one of the social functions of depression. Carers, including physicians and other professional staff, may be especially likely to want to do something for the patient who displays depressive features and psychiatric referral may be more likely on the basis of depressive than anxiety symptoms, for example. This may explain the early case reports of depression in stroke patients which stimulated research on poststroke depression. Subsequent systematic studies of stroke patients almost exclusively focussed on hospitalised cases and patients in rehabilitation programmes and therefore were biased towards inclusion of patients with more severe initial strokes and more persistent disabilities, factors likely to have promoted depression. Depression is also generally liable to become chronic and treatment-resistant in the elderly [37,38]. This not only increases its prominence but also stimulates interest in its aetiology and nature, particularly given the existence of effective treatments for depression in younger patients. Stroke patients are relatively common and as a group provide the opportunity for
359
examination of a variety of aetiological hypotheses about depression in the elderly. Depression may also be simpler to measure than some other psychiatric disorders. Despite ongoing controversies about the nosological status of subtypes o i depressive disorder, there is a plethora of respectable instruments for assessing the presence and severity of nonspecific “depression” and relating it to certain depressive disorders. Most require only assessment of a patient’s symptoms at a specific point in time, rather than longitudinal study, and they are therefore easy and quick to use. By contrast, for example, the lack of equally simple, reliable and validated instruments for assessment of personality, especially in the elderly, has presumably made researchers defer looking for personality change as a function of stroke, despite suggestions that organic personality syndromes may be common and troublesome [36,39]. Other disorders may also masquerade as depression. Many of the symptoms and signs of depression are relatively non-specific and patients with other psychiatric and physical disorders may achieve inflated scores on instruments used to assess depression [40, 41 1. This in turn may lead to over-estimation of the frequency and severity of depression unless other disorders are taken into account. Symptom scores should not be transformed into diagnoses in these patients unless cut-off scores established for use in physically ill patients are used and rigorous diagnostic criteria, including exclusion criteria, are applied. This has not always been done. Scales which only rate severity of depression should not be applied to subjects who do not actually fulfil criteria for a diagnosis of depression. There is a common practice [ 18, 20, 21, 25, 28, 331 of simply using “depression” scores from all subjects, whether depressed or not, on instruments such as the Hamilton Rating Scale for Depression, to examine correlations between post-stroke depression and other factors such as disability; this is of questionable validity, especially when the “depression” scores may be heavily loaded in some patients by physical symptoms not due to depression. It has been suggested that criteria for diagnosis of depression in stroke patients should actually be quite different from those used normally, because neurological signs may both mask and mimic depression (41, 421. The disturbances in motor behaviour, facial expression, verbal communication and cognition which accompany strokes make use of standard assessment instruments difficult as well as raising
RESEARCH INTO PSYCHIATRIC DISORDER AFTER STROKE
360
Table 2. Reported associations hetH,eenpost-stroke deprrssioii mid physicul disubility ~
Time since stroke
Association between depression and physical disability
N
Source of subjects
Robinson and Szetela [ 181
29
Acute hospital
6 - 12 months
No
Feibel and Springer [19]
91
Acute hospital
6 months
No
Robinson and Price [20]
30
Outpatient clinic
