Are Males

More

Likely

William

Objective: is equivalent

G.

lacono,

Ph.D.,

in a large established

and

Morton

Beiser,

diagnostic among

systems.

males

than

than 300 interview

Results: among

The

females.

were identified, 1 75 of whom diagnoses according to five

of schizophrenia

though

M.D.

of 2”i years. A comprehensive community settings where psy-

potential subjects and were assigned

incidence Even

Schizophrenia?

the incidence of schizophrenia made to identify every first-epi-

Canadian city over a period that included hospital and

chotic persons might appear. More underwent a structured psychiatric different

to Develop

This study was undertaken to determine whether for males and females. Method: An attempt was

sode case of psychosis referral network was

higher

Females

Than

was

two

the use ofdifferent

to three

diagnostic

times systems

yielded slightly different risk rates, the elevated risk for males remained consistent. There were no differences between the sexes in the incidence of affective psychosis. In comparison with schizophrenia, the incidence rates for mood disorders with psychotic features were sometimes lower and sometimes higher, depending on the diagnostic system used. Conclusions: The findings, tional (Am

coupled

with

belief

that

reports the

J Psychiatry

in the past

incidence

1992;

1 0 years

ofschizophrenia

nowledge about the sex distribution of psychosis among adults is important for several reasons. Because males and females differ in biology, rate of maturation, social status, and duration and types of experiences encountered, differences in the proportion of males and females afflicted with a disorder can suggest etiological clues (1). Moreover, males are more likely than females to develop psychoses in childhood. Whether this pattern continues with increasing age, thus suggesting that males are more vulnerable to severe psychopathology even in adulthood, is also of great interest. Although authorities have long agreed that the prevalence and incidence of schizophrenia are the same for both sexes (2, 3), surveys in the past 10 years have provided inconsistent results. While studies in Asia (4), Europe (5-8), and North America (9, 10) have suggested an excess of schizophrenia among males, the NaReceived April 16, 1991; revision received Sept. 18, 1991; accepted Dec. 26, 1991. From the Department of Psychology, University of Minnesota, and the Department of Psychiatry, University of British Columbia, Vancouver, Canada. Address reprint requests to Dr. lacono, Department of Psychology, University of Minnesota, 75 East River Road, Minneapolis, MN 55455. Supported by grants from NIMH, the Canada Health and Welfare National Research Directorate Program, the British Columbia Health Care Research Foundation, and the Medical Research Council of Canada. The authors thank J.A.E. Fleming, M.D., T.-Y. Lin, M.D., and M. Moreau, Ph.D., for assistance with clinical data collection and diagand

Copyright

I 070

David

Erickson,

M.A.,

© I 992 American

for

help

Psychiatric

other

is the

investigators,

same

for

challenge

the

two

the conven-

sexes.

149:1070-1074)

K

nosis

from

with

data

Association.

analysis.

tional Institute of Mental Health (NIMH)-sponsored Epidemiological Catchment Area (ECA) survey suggested that among noninstitutionalized populations, rates of schizophrenia are higher among women than among men (11). The World Health Organization (WHO) study of the incidence of schizophrenia (12) demonstrated no consistent pattern of male-female differences across sites. Studies of mood disorder have been more consistent in suggesting that men and women have an equal risk of developing bipolar disorder but that women have higher rates of major depressive disorder (13). However, studies of major depressive disorden have not differentiated between the relatively small percentage of individuals who have affective disorder with psychotic features and those who have affective disorder in general. This report examines sex ratios in a broadly based sample of persons suffering a first episode of psychosis. First-episode subjects are particularly well suited for the study of sex differences. Studies that examine chronic patients risk confounding estimates of the sex distribution with sex differences in the course of psychotic illness, which is known to be more severe in schizophrenic men (14).

To avoid institutionalized

were

recruited

potential

bias

patients

from

associated from

multiple

with

a single

sources

reliance

setting,

both

on

subjects

within

and

outside the traditional mental health care system. The project goal was to come as close as possible to obtaining a sample of all residents in a major Canadian coastal city who were experiencing psychotic symptoms

Am

]

Psychiatry

1 49:8,

August

1992

WILLIAM

for the first time in their lives. Since diagnostic criteria might influence estimates of relative risk, we compared male and female incidence rates (based on the number of new cases identified each year) using different diagnostic systems. To our knowledge the present study is the first to explore sex distributions in a large, community-based, diagnostically heterogeneous sample of first-episode psychotic patients.

METHOD Subjects were recruited in Vancouver, B.C., Canada, from a metropolitan catchment area of approximately 480,000 persons. The referral network included all psychiatnic hospitals and psychiatric services of general hospitals, university and college counseling services, community mental health centers, psychiatrists in private practice, private counseling services, employment and immigration counseling services, and a random sample of one-sixth of all general practitioners in Vancouver. About 1 8% of the referrals were from other

than

inpatient

hospital

services,

including

9%

from

G. IACONO

AND

MORTON

BEISER

terview (the Present State Examination) (15). Information from the psychiatric interview, reviews of clinical charts, and interviews with family members and friends

was brought staff,

to case conferences

including

at least

two

attended

by the project

experienced

diagnosticians;

this process resulted in a “best estimate” diagnosis for each subject. We used five different diagnostic systems, which

(16) var-

ied in the breadth of their definition of schizophrenia, to classify participants: DSM-III, ICD-9, the Research Diagnostic Criteria (RDC) (17), the Feighner et al. critenia (1 8), and the 12-point flexible system of Carpenter et al. (19). With the exception of ICD-9, each of these systems has an explicit set of criteria for making diagnoses. To adapt the fairly loose ICD-9 psychotic disor-

den categories cians

criteria the

for research

used

a checklist

derived

ICD-9

from

purposes, of

the project

symptoms

the clinical

and

clini-

diagnostic

constructs

described

in

manual.

To ensure

that

subjects

received

the

most

accurate

diagnoses possible, all symptoms and diagnostic cnitena associated with the psychotic disorders described in each diagnostic system were reviewed for each patient

community mental health centers, 7% from private practice clinicians and community agencies, and 2% from hospital outpatient services. Over a period of 2 years beginning in 1982, we identified a total of 318 potential subjects for our study. Of these, 3 1 terminated contact with their referral source or disappeared before

to determine whether each symptom was present or absent. Then the diagnostic algorithms specified for each system (or the descriptive guidelines presented in ICD-9) were strictly followed to arrive at a diagnosis. Only subjects who satisfied the criteria for an active

we could contact viewed. Although

were

entered

into

ages,

sex,

them, and 94 refused these 125 nonparticipants

our

and

study,

the

we were

diagnoses

able

to be interwere not

to ascertain

assigned

by the

episode

all of whom were sode of psychosis, in the study.

To cast as wide

of psychosis.

Thus,

experiencing gave informed

their first lifetime epiconsent to participate

a referral

175 individuals,

net as possible,

we supplied

our referral agencies with a broad definition of potential cases, including persons 1 ) who were currently psychotic (i.e., experiencing hallucinations or delusions, displaying grossly disorganized behavior, showing marked thought and speech disorder, or having two of the following symptoms: marked loss of drive, social withdrawal, severe excitement, overwhelming anxiety or fear, and gross self-neglect) and 2) who had not been treated before the present episode with antipsychotic, antimanic, or antidepressant drugs. Other inclusion and exclusion criteria required 1 ) that the subjects had lived in the Vancouver metropolitan area for at least 6 months, 2) that they were between 15 and 54 years of

age,

and

illness, disorder, clinical cluding cruited

Am

]

3) that

they

did not

have

an organic

cerebral

severe mental retardation, a chronic physical or chemical dependence. A psychiatrist psychologist examined all potential subjects, doubtful and borderline cases, initially for the study using a structured psychiatric

Psychiatry

1 49:8,

August

1992

disorder

retained

in at

least

one

diagnostic

system

for study.

their

referral

sources. An additional 1 8 subjects agreed to participate but were dropped when they were found not to be psychotic or to be ineligible because they had experienced

a previous

psychotic

or inrein-

RESULTS To determine whether an excess of patients of either sex was present in a category or group, we used chisquare tests to compare observed frequencies against the a priori expectation that the sexes would be equally represented. Among the I 75 participants, who ranged in age from 16 to SO years (mean=2S.0 years, SD=7.8, for males; mean=25.7 years, SD=8.9, for females), 68% (N=1 1 9) were male, a proportion that deviated significandy from the expected rate of 50% (goodness-of-fit X222.68 ticipants system

df=1, p

Are males more likely than females to develop schizophrenia?

This study was undertaken to determine whether the incidence of schizophrenia is equivalent for males and females...
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