Cocaine-Induced
Paranoia
Sally
L. Satel,
Objective: The aim transient cocaine-induced cocaine-dependent
undergoing The
men
men
substance were
measures
Results:
The combined strongly
who
had
been
using
treatment;
with
with
on the Perceptual a history
may
experience (Am
J
be at higher
risk
for
power users
development
Scale
week
and
the Magical
and
Ideation
Scale
and Magical The
90.0%, transient than
were
paranoia.
offunctional
paranoia.
were 80.0%, who experience ofpsychosis
per
cocaine-induced
the development
Aberration
who experience subjects were 20
Scale,
psychosis.
Ideation
sensitivity,
Scale specific-
88.9%, and 81.8%, paranoia while in-
cocaine
users
who
do not
paranoia. Psychiatry
1 991
; 148:1
708-1
71 1)
I
is web! known that drugs of abuse can produce both transient and persistent psychotic symptoms in mdividuabs without histories of primary psychotic illness (1-3). Whether such individuals possess an underlying predisposition to psychosis in the absence of pharmacobogic stress is unknown. Evidence of such a predisposition has been provided by several studies. Tsuang et al. (4) studied consecutively admitted substance users with and without psychosis. Use of habbucinogens and cannabinoids was highly prevalent in the 72 substance abusers who developed psychoses; their premombid histories and symptoms were comparable to those of a group of schizophrenic patients. By contrast, a comparison group of 30 substance abusers who did not develop psychosis tended to use drugs without psychotomimetic properties-barbiturates, benzodiazepines, and opiates. Bowers and Swigar (5) examined 95 patients hospitalized for acute psychosis; 60 had used hallucinogens within 3 years of admission. Among the male subjects, those with positive family histories of major mental illness appeared capable of becoming psychotic with relatively small amounts of hallucinogen, whereas those without such histories required greater exposure. In a 6-year follow-up of 1 1 amphetamine usems who were asymptomatic at the time of initial treatment, McLellan et al. (6) diagnosed seven as psychotic; none of the opiate abusers or alcoholics was psychotic
Received Jan. 2, 1991; revision received May 15, 1991; accepted June 14, 1991. From the Department of Psychiatry, Yale University School of Medicine, and the Yale Psychiatric Institute, New Haven, Conn., and the Psychiatry Service, West Haven VA Medical Center. Address reprint requests to Dr. Satel, Psychiatry Service 1 1 6A, VA Medical Center, 950 Campbell Ave., West Haven, CT 06516.
1708
Ph.D.
5 g of cocaine
of cocaine-induced
and positive and negative predictive respectively. Conclusions: Heavy cocaine
Proneness
individuals Method: The
binge-limited
to precede
ity,
toxicated
S. Edell,
than
Aberration
thought
scores
more
halfreported
the Perceptual
ofsymptoms
correlated
and William
M.D.,
this study was to determine whether paranoia are vulnerable to psychosis.
abuse
assessed
self-report were
of
and Psychosis
at follow-up. These investigators and others (1, 7, 8) have speculated that subthreshold psychotic symptoms may have actually influenced the subjects’ selection of drugs and that symptoms associated with psychotic disorders may have been present but below the limit of clinical detection at the time drug use began. Cocaine use has been associated with paranoia, but not all users develop this symptom despite prolonged and heavy exposure (9-1 1). In our earlier study (12) of cocaine-dependent men, none of whom had other axis I diagnoses, 34 (68%) reported paranoid episodes limited to their periods of cocaine use. The paranoia did not extend beyond the “crash,” or hypersomnolent phase, of early cocaine abstinence. The paranoia had developed after an average of 3 years’ use. Importantly, the subjects reporting paranoia did not differ significantly from those not reporting paranoia with respect to use characteristics such as route of administration, lifetime duration of use, cumulative exposure to cocaine, amount of cocaine consumed in month of admission, or concurrent use of other drugs. These findings suggest that development of paranoia is not simply the result of exceeding a threshold of use and that affected individuals may be predisposed to this drug-induced state. Chapman et al. have developed a series of objective scales that attempt to identify individuals at higher than normal risk for psychosis. Two of the most promising scales measure perceptual aberrations (1 3) and magical ideation (14). These scales ascertain, through self-report, experiences that are characteristic of nascent psychotic states. Numerous published studies (15-20) have documented the reliability and validity of these instruments. Unlike the standard approach of studying the
so
Am
J
Psychiatry
1 48:1 2, December
1991
SALLY
relatives of psychotic patients, which may generate an unrepresentative and restricted risk sample, this strategy measures symptoms that are thought to precede psychosis and allows for the study of a greater variety of individuals with psychotic diathesis (16). In the present study we attempted to answer the question of whether individuals who display transient cocaine-induced paranoid symptoms are predisposed to psychosis. We hypothesized that scores on the scales of psychosis proneness would discriminate between mdividuabs who display such paranoid symptoms and those who do not.
METhOD
Subjects The subjects were recruited from patients consecutiveby admitted to the inpatient and outpatient units of a VA substance abuse treatment program. A total of 32 patients were screened with the Cocaine Experience Questionnaire (description to follow). The first 10 patients who reported binge-limited (transient) paranoid experiences during cocaine intoxication and the first 10 who denied such experiences were included. It was necessary to exclude 12 patients to achieve this distribution because patients who reported paranoia were overrepresented among the heavy cocaine users (12, 21). The subjects were assigned to groups blindly, i.e., the subjects were determined to be psychosis prone by one author (W.S.E.), who had no knowledge of the specific subjective response to cocaine, and the response to cocaine was determined by the other author (S.L.S.). The inclusion criteria for the study were as follows. 1 . Primary DSM-III-R axis I diagnosis of cocaine depcndcncc and a minimum of 3 years of continuous use of at least approximately S g of cocaine per week. The latter requirement was based on our earlier work (12), which demonstrated that development of paranoia in vulnerable individuals occurs after an average of 3 years’ use of at least S g of cocaine per week. 2. No concurrent DSM-III-R substance dependence diagnosis or other axis I affective or psychotic disorder. A patient who used another substance was included if the substance was used to modify the acute effects of cocaine and if such use did not take place in the absence of cocaine intoxication. 3. No prior psychiatric hospitalizations except for detoxification and rehabilitation. 4. Absence of psychotic symptoms or paranoia outside the context of cocaine use. S. Absence of DSM-III-R axis II diagnoses of schizotypal on schizoid personality disorder. 6. Negative family history of psychosis in first-degree relatives. The study was designed so that the final group of 20 male subjects was equally divided between those reporting cocaine-induced paranoia and those not reporting such symptoms. All those invited agreed to participate.
Am
J
Psychiatry
I 48:1 2, December
1991
U. SATEL
AND
WILLIAM
S. EDEUL
Instruments The Cocaine Experience Questionnaire contains 58 items and assesses methods and patterns of cocaine use and the extent and nature of the paranoid experiences associatedwith use. Family history of functional psychotic symptoms was elicited during administration of the questionnaire. The subjects were carefully instructed to distinguish adaptive hypervigilance or anxiety in high-risk situations (e.g., making drug deals, passing through housing projects, engaging in illicit activities) from completely irrational beliefs (e.g., the perception that the police were standing on the window ledge outside the subject’s 10thfloor apartment). This questionnaire was administered by a rater and typically took 20 minutes for a subject who did not report paranoid experiences and 30-4S minutes for a subject who did. The original development of the Scales of Psychosis Proneness largely followed the sequential steps recommended by Jackson for development of personality scales (22). Items were written and judged according to how well they met trait specifications based on Meehl’s descriptions (23) of these characteristics. Careful attention was given to minimizing bias due to social desirability and acquiescent response style while maximizing item-scale correlations. The Perceptual Aberration Scale is a 35-item truefalse measure of perceptual distortions of body image and of visual and auditory stimuli (13). Analyses of intemnal consistency (13) have revealed alpha values around 0.90 and negligible correlations with age, education, social class, social desirability, and acquiescent response style. Stability of scores, as shown by testretest reliability coefficients, is high (m=0.75) ( 1 7). Representative items (and answers indicating perceptual distortion) include “Parts of my body occasionally seem dead or unreal” (true) and “My hands or feet have never seemed far away” (false). The Magical Ideation Scale is a 30-item true-false scale that measures belief in forms of causation that by conventional standards are invalid (14). Negligible comrelations with age, education, social class, social desimability, and acquiescent response style have been observed (14). Internal consistency has been shown by coefficient alphas in the mid 0.80s, and stability of scores is indicated by test-retest reliability coefficients of 0.80 (17). Representative items (and answers indicating magical ideation) include “Some people can make me aware of them just by thinking of me” (true) and “Homoscopes are might too often for it to be a coincidence” (true). The subjects were given special instructions for filling out the Perceptual Aberration Scale and Magical Ideation Scale. They were told that an occasional item might refer to an experience they had had only when taking drugs and that, unless they had had the experience at other times, they were to mark the item as if they had not had that experience. The mean±SD score on the Perceptual Aberration Scale was 685±7.16, whereas the median was 5.00, in-
1709
COCAINE-INDUCED
dicating
the
PARANOIA
distribution
of
scores
was
positively
skewed. The mean score on the Magical Ideation Scale was 10.15±6.12, and the median was 8.50, so the distribution of scores on this scale was also positively skewed. These group scores were virtually identical to scores on these instruments for large samples of male undergraduate students (Perceptual Aberration Scale= 6.87±6.06; Magical Ideation Scalc=9.73±S.83 ) (L.J. Chapman and J.P. Chapman, unpublished norms, April 1 1, 1989), which showed similarly skewed distnibutions.
As
noted
however,
there
in classifying
by
Lcnzenweger
and
are no established individuals
Loranger
cutoff
among
(20),
scores
for use
nonstudent
clinical
populations as at high and low risk for psychosis. Given the skewed distribution of scores in our group, we fobbowed their strategy of dividing subjects at the group median, which we defined as the total of the median scores on the Perceptual Aberration Scale and Magical Ideation Scale, 13.5. Thus, subjects who scored 13 or lower were considered low risk and those who scored above 1 3 were designated high risk.
RESULTS
Ofthe 10 subjects who reported cocaine-induced pamanoia, eight scored above the combined median score on the Perceptual Aberration Scale and Magical Ideation Scale. Of the 10 who did not report cocaine-rebated pamanoia, only one scored above the median. The strong posi-
nience of cocaine-induced paranoia (or, perhaps, the drug-induced neurobiobogic changes underlying this symptom) increase the likelihood of having perceptual aberrations and magical ideation, or are these latter cxpeniences an expression of an intrinsic vulnerability to paranoia that predated cocaine consumption in otherwise asymptomatic individuals? Chronic cocaine use affects dopaminergic systems (26, 27). These systems have bong been associated with schizophrenia. Thus, cocaine self-administration may represent a quasinaturabistic method for stressing the neurotransmitter system most often linked to the positive symptoms of schizophrenia. Some individuals respond to the pharmacologic stress of cocaine by developing transient paranoid symptoms, and it is largely these individuals whose scores on the two scales of psychosis proneness were in the high-risk mange. Perhaps those who develop transient cocaine-induced paranoia possess intrinsic, subclinical vulnerability of the dopaminergic system, a marker of which is endorsement of specific responses on these scales. Although speculative, the concept that dopaminergic dysregulation may underlie forms of both functional and drug-induced paranoia is of considerable heuristic value in the investigation of neurobiological mechanisms of vulnerability It seems reasonable
abs are at high chosis,
to psychosis.
risk
particularly
of
pharmacologic
sity of paranoia and caine binges appear
with
sensitization
size (24),
van-
that
schizophrenic
rate,
significantly
ancc.
It should
for almost
be noted
that
50% in this
of the shared group
the
base
or proportion of individuals who developed cocaine-induced paranoia, was 50.0% (10 of 20) and the selection ratio, or proportion of individuals who were predicted to be psychosis prone, was 45.0% (nine of 20), so the maximum possible phi coefficient was 0.9045. Only ifthe base rate and selection ratio arc equal can a test achieve perfect
than caine. stress
validity (i.e., phi=1.00) ity of the symptom psychosis proneness, ability of not having
this
(25). The of paranoia was 80.0%. cocaine-induced
sensitivity, or probabilgiven the diagnosis of The specificity, or probparanoia given the
absence of psychosis proneness, was predictive powem or probability of given the presence of paranoia, was predictive power, or probability of prone given the absence of paranoia,
90.0%. The positive psychosis proneness 88.9%. The negative not being psychosis was 8 1.8%.
The present who experience port symptoms,
study provides evidence that individuals transient cocaine-induced paranoia reoccurring in the drug-free state, that
are
with
associated
1710
psychosis
proneness.
and correlational, of causality. That
As the it is impossible
is, does
the to
(12,
more
likely
were schizophrenic The relationship of chronic cocaine
quality,
stress.
rapidity increase
when
Indeed,
of its onset oven time,
21 ). Brady
patients
that such individuof prolonged psy-
who
who the the
reported
cocaine
to be of the paranoid patients between exposure,
inten-
during coconsistent
et al. (28) abused
under
the
were
subtype
did not use pharmacologic development
coof
paranoid symptoms, and the onset of psychosis is Unknown. Clearly, larger-scale studies with a longitudinal prospective design are required for full exploration of question
and
for
definitive
determination
whether deviant responses on the proneness scales cede the development of cocaine-induced paranoia persons just beginning long-term cocaine abuse.
of
prein
REFERENCES
DISCUSSION
was cross-sectional determine direction
paranoid
or emotional
tive correlation between cocaine-induced paranoia and psychosis proneness (Fisher’s exact test, p=O.OO3; phi cocfficicnt=0.7035, p
Paranoia
Sally
L. Satel,
Objective: The aim transient cocaine-induced cocaine-dependent
undergoing The
men
men
substance were
measures
Results:
The combined strongly
who
had
been
using
treatment;
with
with
on the Perceptual a history
may
experience (Am
J
be at higher
risk
for
power users
development
Scale
week
and
the Magical
and
Ideation
Scale
and Magical The
90.0%, transient than
were
paranoia.
offunctional
paranoia.
were 80.0%, who experience ofpsychosis
per
cocaine-induced
the development
Aberration
who experience subjects were 20
Scale,
psychosis.
Ideation
sensitivity,
Scale specific-
88.9%, and 81.8%, paranoia while in-
cocaine
users
who
do not
paranoia. Psychiatry
1 991
; 148:1
708-1
71 1)
I
is web! known that drugs of abuse can produce both transient and persistent psychotic symptoms in mdividuabs without histories of primary psychotic illness (1-3). Whether such individuals possess an underlying predisposition to psychosis in the absence of pharmacobogic stress is unknown. Evidence of such a predisposition has been provided by several studies. Tsuang et al. (4) studied consecutively admitted substance users with and without psychosis. Use of habbucinogens and cannabinoids was highly prevalent in the 72 substance abusers who developed psychoses; their premombid histories and symptoms were comparable to those of a group of schizophrenic patients. By contrast, a comparison group of 30 substance abusers who did not develop psychosis tended to use drugs without psychotomimetic properties-barbiturates, benzodiazepines, and opiates. Bowers and Swigar (5) examined 95 patients hospitalized for acute psychosis; 60 had used hallucinogens within 3 years of admission. Among the male subjects, those with positive family histories of major mental illness appeared capable of becoming psychotic with relatively small amounts of hallucinogen, whereas those without such histories required greater exposure. In a 6-year follow-up of 1 1 amphetamine usems who were asymptomatic at the time of initial treatment, McLellan et al. (6) diagnosed seven as psychotic; none of the opiate abusers or alcoholics was psychotic
Received Jan. 2, 1991; revision received May 15, 1991; accepted June 14, 1991. From the Department of Psychiatry, Yale University School of Medicine, and the Yale Psychiatric Institute, New Haven, Conn., and the Psychiatry Service, West Haven VA Medical Center. Address reprint requests to Dr. Satel, Psychiatry Service 1 1 6A, VA Medical Center, 950 Campbell Ave., West Haven, CT 06516.
1708
Ph.D.
5 g of cocaine
of cocaine-induced
and positive and negative predictive respectively. Conclusions: Heavy cocaine
Proneness
individuals Method: The
binge-limited
to precede
ity,
toxicated
S. Edell,
than
Aberration
thought
scores
more
halfreported
the Perceptual
ofsymptoms
correlated
and William
M.D.,
this study was to determine whether paranoia are vulnerable to psychosis.
abuse
assessed
self-report were
of
and Psychosis
at follow-up. These investigators and others (1, 7, 8) have speculated that subthreshold psychotic symptoms may have actually influenced the subjects’ selection of drugs and that symptoms associated with psychotic disorders may have been present but below the limit of clinical detection at the time drug use began. Cocaine use has been associated with paranoia, but not all users develop this symptom despite prolonged and heavy exposure (9-1 1). In our earlier study (12) of cocaine-dependent men, none of whom had other axis I diagnoses, 34 (68%) reported paranoid episodes limited to their periods of cocaine use. The paranoia did not extend beyond the “crash,” or hypersomnolent phase, of early cocaine abstinence. The paranoia had developed after an average of 3 years’ use. Importantly, the subjects reporting paranoia did not differ significantly from those not reporting paranoia with respect to use characteristics such as route of administration, lifetime duration of use, cumulative exposure to cocaine, amount of cocaine consumed in month of admission, or concurrent use of other drugs. These findings suggest that development of paranoia is not simply the result of exceeding a threshold of use and that affected individuals may be predisposed to this drug-induced state. Chapman et al. have developed a series of objective scales that attempt to identify individuals at higher than normal risk for psychosis. Two of the most promising scales measure perceptual aberrations (1 3) and magical ideation (14). These scales ascertain, through self-report, experiences that are characteristic of nascent psychotic states. Numerous published studies (15-20) have documented the reliability and validity of these instruments. Unlike the standard approach of studying the
so
Am
J
Psychiatry
1 48:1 2, December
1991
SALLY
relatives of psychotic patients, which may generate an unrepresentative and restricted risk sample, this strategy measures symptoms that are thought to precede psychosis and allows for the study of a greater variety of individuals with psychotic diathesis (16). In the present study we attempted to answer the question of whether individuals who display transient cocaine-induced paranoid symptoms are predisposed to psychosis. We hypothesized that scores on the scales of psychosis proneness would discriminate between mdividuabs who display such paranoid symptoms and those who do not.
METhOD
Subjects The subjects were recruited from patients consecutiveby admitted to the inpatient and outpatient units of a VA substance abuse treatment program. A total of 32 patients were screened with the Cocaine Experience Questionnaire (description to follow). The first 10 patients who reported binge-limited (transient) paranoid experiences during cocaine intoxication and the first 10 who denied such experiences were included. It was necessary to exclude 12 patients to achieve this distribution because patients who reported paranoia were overrepresented among the heavy cocaine users (12, 21). The subjects were assigned to groups blindly, i.e., the subjects were determined to be psychosis prone by one author (W.S.E.), who had no knowledge of the specific subjective response to cocaine, and the response to cocaine was determined by the other author (S.L.S.). The inclusion criteria for the study were as follows. 1 . Primary DSM-III-R axis I diagnosis of cocaine depcndcncc and a minimum of 3 years of continuous use of at least approximately S g of cocaine per week. The latter requirement was based on our earlier work (12), which demonstrated that development of paranoia in vulnerable individuals occurs after an average of 3 years’ use of at least S g of cocaine per week. 2. No concurrent DSM-III-R substance dependence diagnosis or other axis I affective or psychotic disorder. A patient who used another substance was included if the substance was used to modify the acute effects of cocaine and if such use did not take place in the absence of cocaine intoxication. 3. No prior psychiatric hospitalizations except for detoxification and rehabilitation. 4. Absence of psychotic symptoms or paranoia outside the context of cocaine use. S. Absence of DSM-III-R axis II diagnoses of schizotypal on schizoid personality disorder. 6. Negative family history of psychosis in first-degree relatives. The study was designed so that the final group of 20 male subjects was equally divided between those reporting cocaine-induced paranoia and those not reporting such symptoms. All those invited agreed to participate.
Am
J
Psychiatry
I 48:1 2, December
1991
U. SATEL
AND
WILLIAM
S. EDEUL
Instruments The Cocaine Experience Questionnaire contains 58 items and assesses methods and patterns of cocaine use and the extent and nature of the paranoid experiences associatedwith use. Family history of functional psychotic symptoms was elicited during administration of the questionnaire. The subjects were carefully instructed to distinguish adaptive hypervigilance or anxiety in high-risk situations (e.g., making drug deals, passing through housing projects, engaging in illicit activities) from completely irrational beliefs (e.g., the perception that the police were standing on the window ledge outside the subject’s 10thfloor apartment). This questionnaire was administered by a rater and typically took 20 minutes for a subject who did not report paranoid experiences and 30-4S minutes for a subject who did. The original development of the Scales of Psychosis Proneness largely followed the sequential steps recommended by Jackson for development of personality scales (22). Items were written and judged according to how well they met trait specifications based on Meehl’s descriptions (23) of these characteristics. Careful attention was given to minimizing bias due to social desirability and acquiescent response style while maximizing item-scale correlations. The Perceptual Aberration Scale is a 35-item truefalse measure of perceptual distortions of body image and of visual and auditory stimuli (13). Analyses of intemnal consistency (13) have revealed alpha values around 0.90 and negligible correlations with age, education, social class, social desirability, and acquiescent response style. Stability of scores, as shown by testretest reliability coefficients, is high (m=0.75) ( 1 7). Representative items (and answers indicating perceptual distortion) include “Parts of my body occasionally seem dead or unreal” (true) and “My hands or feet have never seemed far away” (false). The Magical Ideation Scale is a 30-item true-false scale that measures belief in forms of causation that by conventional standards are invalid (14). Negligible comrelations with age, education, social class, social desimability, and acquiescent response style have been observed (14). Internal consistency has been shown by coefficient alphas in the mid 0.80s, and stability of scores is indicated by test-retest reliability coefficients of 0.80 (17). Representative items (and answers indicating magical ideation) include “Some people can make me aware of them just by thinking of me” (true) and “Homoscopes are might too often for it to be a coincidence” (true). The subjects were given special instructions for filling out the Perceptual Aberration Scale and Magical Ideation Scale. They were told that an occasional item might refer to an experience they had had only when taking drugs and that, unless they had had the experience at other times, they were to mark the item as if they had not had that experience. The mean±SD score on the Perceptual Aberration Scale was 685±7.16, whereas the median was 5.00, in-
1709
COCAINE-INDUCED
dicating
the
PARANOIA
distribution
of
scores
was
positively
skewed. The mean score on the Magical Ideation Scale was 10.15±6.12, and the median was 8.50, so the distribution of scores on this scale was also positively skewed. These group scores were virtually identical to scores on these instruments for large samples of male undergraduate students (Perceptual Aberration Scale= 6.87±6.06; Magical Ideation Scalc=9.73±S.83 ) (L.J. Chapman and J.P. Chapman, unpublished norms, April 1 1, 1989), which showed similarly skewed distnibutions.
As
noted
however,
there
in classifying
by
Lcnzenweger
and
are no established individuals
Loranger
cutoff
among
(20),
scores
for use
nonstudent
clinical
populations as at high and low risk for psychosis. Given the skewed distribution of scores in our group, we fobbowed their strategy of dividing subjects at the group median, which we defined as the total of the median scores on the Perceptual Aberration Scale and Magical Ideation Scale, 13.5. Thus, subjects who scored 13 or lower were considered low risk and those who scored above 1 3 were designated high risk.
RESULTS
Ofthe 10 subjects who reported cocaine-induced pamanoia, eight scored above the combined median score on the Perceptual Aberration Scale and Magical Ideation Scale. Of the 10 who did not report cocaine-rebated pamanoia, only one scored above the median. The strong posi-
nience of cocaine-induced paranoia (or, perhaps, the drug-induced neurobiobogic changes underlying this symptom) increase the likelihood of having perceptual aberrations and magical ideation, or are these latter cxpeniences an expression of an intrinsic vulnerability to paranoia that predated cocaine consumption in otherwise asymptomatic individuals? Chronic cocaine use affects dopaminergic systems (26, 27). These systems have bong been associated with schizophrenia. Thus, cocaine self-administration may represent a quasinaturabistic method for stressing the neurotransmitter system most often linked to the positive symptoms of schizophrenia. Some individuals respond to the pharmacologic stress of cocaine by developing transient paranoid symptoms, and it is largely these individuals whose scores on the two scales of psychosis proneness were in the high-risk mange. Perhaps those who develop transient cocaine-induced paranoia possess intrinsic, subclinical vulnerability of the dopaminergic system, a marker of which is endorsement of specific responses on these scales. Although speculative, the concept that dopaminergic dysregulation may underlie forms of both functional and drug-induced paranoia is of considerable heuristic value in the investigation of neurobiological mechanisms of vulnerability It seems reasonable
abs are at high chosis,
to psychosis.
risk
particularly
of
pharmacologic
sity of paranoia and caine binges appear
with
sensitization
size (24),
van-
that
schizophrenic
rate,
significantly
ancc.
It should
for almost
be noted
that
50% in this
of the shared group
the
base
or proportion of individuals who developed cocaine-induced paranoia, was 50.0% (10 of 20) and the selection ratio, or proportion of individuals who were predicted to be psychosis prone, was 45.0% (nine of 20), so the maximum possible phi coefficient was 0.9045. Only ifthe base rate and selection ratio arc equal can a test achieve perfect
than caine. stress
validity (i.e., phi=1.00) ity of the symptom psychosis proneness, ability of not having
this
(25). The of paranoia was 80.0%. cocaine-induced
sensitivity, or probabilgiven the diagnosis of The specificity, or probparanoia given the
absence of psychosis proneness, was predictive powem or probability of given the presence of paranoia, was predictive power, or probability of prone given the absence of paranoia,
90.0%. The positive psychosis proneness 88.9%. The negative not being psychosis was 8 1.8%.
The present who experience port symptoms,
study provides evidence that individuals transient cocaine-induced paranoia reoccurring in the drug-free state, that
are
with
associated
1710
psychosis
proneness.
and correlational, of causality. That
As the it is impossible
is, does
the to
(12,
more
likely
were schizophrenic The relationship of chronic cocaine
quality,
stress.
rapidity increase
when
Indeed,
of its onset oven time,
21 ). Brady
patients
that such individuof prolonged psy-
who
who the the
reported
cocaine
to be of the paranoid patients between exposure,
inten-
during coconsistent
et al. (28) abused
under
the
were
subtype
did not use pharmacologic development
coof
paranoid symptoms, and the onset of psychosis is Unknown. Clearly, larger-scale studies with a longitudinal prospective design are required for full exploration of question
and
for
definitive
determination
whether deviant responses on the proneness scales cede the development of cocaine-induced paranoia persons just beginning long-term cocaine abuse.
of
prein
REFERENCES
DISCUSSION
was cross-sectional determine direction
paranoid
or emotional
tive correlation between cocaine-induced paranoia and psychosis proneness (Fisher’s exact test, p=O.OO3; phi cocfficicnt=0.7035, p
