470 first-contact patients with nonaffective functional psychosis
Incidence
The ratio of male to female incidence rates rose progressively when RDC (1.2), DSM-III-R (1.3), DSM-III (2.2), and Feighner (2.5) criteria for schizophrenia were applied. Schizophrenia was most common in young males and least common in older males, with females occupying an intermediate position.
Gender differences in incidence rates were found in patients with schizophrenia and schizophrenia-like psychosis, being higher in males. However, no gender differences were found in terms of prevalence. These results may depend on the stringency of the diagnostic criteria applied (i.e., age cut-off or a narrower definition of schizophrenia in terms of symptomatology and duration of symptoms): the broader the criteria the less significant the gender differences in incidence or prevalence.
38 publications on “incidence of schizophrenia” published during the period between January 1980 and September 2001
Incidence
The incidence risk ratios for men developing schizophrenia relative to women were 1.42 (95% [CI], 1.30–1.56) when all studies were included in the analysis (49 effect sizes). This risk remained significantly higher in men after controlling for potentially confounding factors (i.e. age bias, criterion bias, and hospital bias).
A total of 1,721 prevalence estimates from 188 studies
Prevalence
No significant differences in prevalence of schizophrenia were found between males and females. For the male: female estimate ratio (based on 57 ratios), the median value was 1.11, and the 10% and 90% quantiles were 0.50 to 1.70.
248 subjects, 30 years or older, with a diagnosis of any psychotic disorder
LTP
The LTP was 3.06% for any psychotic disorder, and regarding gender it was 3.11% for men vs. 3.01% for women. In particular, in relation to schizophrenia diagnosis no gender differences were observed in the prevalence data.
For the incidence analysis, 158 studies that generated 1,458 rates For the prevalence analysis, 188 studies that provided 1,721 prevalence estimates
Incidence and prevalence
The distribution of incidence rates differed significantly between males and females, and the median (10, 90 percent quantiles) rate ratio for male : female estimates was 1.4 (0.9, 2.4). The gender difference identified in the incidence rates is not reflected in prevalence estimates (the median lifetime prevalence estimates for males were 3.7 per 1,000 vs. 3.8 per 1,000 for females)
Positive, negative, excited, anxious/depressive, and cognitive symptoms
No gender differences were found in the 5-factor model of schizophrenia, including positive, negative, excited, anxious/depressive and cognitive factors.
No consensus exists regarding gender differences in the clinical expression of psychosis. This could be due to clinical and/or methodological factors. Studies showing gender differences obtained discordant results. However, the most replicated findings suggest that mood symptoms are common in women with schizophrenia or FEP, while negative symptoms tend to be more predominant in men.
1090 cases of affective and nonaffective psychosis
Positive, affective, and negative symptoms
In schizophrenia specifically, women were significantly less likely than men to report having hallucinations, delusions or poor concentration currently, and more likely to report at least one serious episode of dysphoria over a lifetime. Within all groups, women were less likely than men to experience negative symptoms.
53 consecutive cases with a first psychotic episode
Negative symptoms and insight
In the group of younger patients, men showed more negative symptoms and poorer insight than women. No gender differences were observed in the clinical expression of the episode in the older group of patients.
267 first-admitted patients with nonaffective functional psychosis
Premorbid and social and occupational functioning
Males had lower social role functioning than females prior to first admission, and of those patients who achieved adequate role functioning, males had greater deterioration in social and occupational functioning after onset.
Better social functioning appears to be a particular strength of women with psychosis spectrum disorders compared to men. However, not all studies confirm this finding. Methodological issues could explain these discrepancies (i.e., sample size, lack of sample representativeness, and measures used to assess social functioning).
There were no gender differences in premorbid functioning (measured by the GAF). Males experienced lower levels of functioning, being less likely to be working/studying, and more likely to be living with their family.
231 community-dwelling individuals with schizophrenia
Social functioning
Women scored higher in social functioning (LSP). While men’s social functioning is affected by positive symptoms, women’s social functioning is impaired by disorganized symptoms.
Four independent schizophrenic cohorts: two groups of inpatients with chronic courses at a research hospital (), one group of consecutive admissions to a private psychiatric hospital (), and one group of schizophrenic twins from discordant monozygotic pairs ()
Neuropsychological performance
Not one comparison significantly favored women, and few were even significantly different by gender.
The inconsistencies in the results may be due mainly to methodological questions (i.e., samples of convenience including not representative male and female patients, analysis not controlling clinical variables, lack of normal comparison group, or lack of consensus in measures used).