Table 2.

Overview of gender differences in psychosis spectrum disorder studies: controversial results and main conclusions.

	Study	Sample characteristics*	Outcome measures	Key finding**	Main conclusion
Epidemiology	Castle et al., 1993 [28]	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.
	Aleman et al., 2003 [29]	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).
	Saha et al., 2005 [30]	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.
	Perälä et al., 2007 [31]	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.
	McGrath et al., 2008 [32]	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)
Clinical expression	Lindström and Von Knorring, 1994 [40]	140 patients with schizophrenic syndromes	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.
	Szymanski et al., 1995 [41]	54 patients with first-episode schizophrenia	Affective and positive symptoms	Females displayed significantly less illogical thinking, but more anxiety, inappropriate affect and bizarre behavior than the men.
	Gur et al., 1996 [42]	272 patients with schizophrenia	Negative and positive symptoms	A greater severity of negative symptoms in men and identical severity of positive symptoms for men and women in all age groups were observed.
	Hayashi et al., 2002 [43]	308 patients with DSM-IV schizophrenia	Positive, negative, excited, anxious/depressive, and cognitive symptoms	In a five-factorial structure model of PANSS the factors and component symptoms were common across gender.
	Morgan et al., 2008 [44]	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.
	Cotton et al., 2009 [45]	661 patients with first episode psychosis	Depressive symptoms	Females were more likely to have depressive symptoms while males experienced more severe psychopathology.
	Barajas et al., 2010 [46]	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.
	Galderisi et al., 2012 [47]	276 patients with spectrum disorders of schizophrenia	Negative symptoms	Female patients, as compared with males, showed fewer negative symptoms.
Social functioning	Häfner et al., 1993 [59]	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).
	Andia et al., 1995 [60]	85 outpatients with schizophrenia	Psychosocial functioning	Women exhibited better psychosocial functioning (better educated and more often married, living independently, and employed).
	Usall et al., 2002 [61]	200 outpatients with schizophrenia (DSM-IV criteria)	General functioning and disability	Gender influenced significantly on DAS (occupational and personal care) and GAF, with men showing worse functioning.
	Grossman et al., 2008 [62]	97 patients with schizophrenia and other psychotic disorders	Global functioning	Women showed significantly better global functioning at 3 of the 6 follow-ups (the 2-, 7.5-, and 10-year follow-ups).
	Cotton et al., 2009 [45]	661 patients with first episode psychosis	Premorbid and 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.
	Bottlender et al., 2010 [64]	177 patients with life-time diagnoses belonging to the schizophrenic, schizoaffective, or affective spectrum (ICD-10 criteria)	Social disability	No gender differences were found in social disability using DAS scale.
	Vila-  Rodriguez et al., 2011 [63]	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.
	Galderisi et al., 2012 [47]	295 stabilized patients with schizophrenia, schizoaffective, or delusional disorder	Social functioning	No significant effect of gender was observed on any index of social functioning.
Cognitive functioning	Goldberg et al., 1995 [73]	Four independent schizophrenic cohorts: two groups of inpatients with chronic courses at a research hospital (N = 191), one group of consecutive admissions to a private psychiatric hospital (N = 57), and one group of schizophrenic twins from discordant monozygotic pairs (N = 20)	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).
	Lewine et al., 1996 [69]	195 patients with schizophrenia or schizoaffective disorder	Neuropsychological functioning	Women performed significantly more poorly than men in verbal memory, spatial memory, and visual processing.
	Purcell et al., 1998 [70]	159 patients with schizophrenia or schizoaffective disorder	VIQ and PIQ	Significantly more men than women with schizophrenia exhibited a VIQ > PIQ pattern.
	Moriarty et al., 2001 [74]	205 geriatric patients with lifelong poor-outcome schizophrenia	Cognitive impairment	No gender differences in cognitive functioning were found.
	Bozikas et al., 2010 [71]	96 schizophrenia patients	Basic cognitive abilities	The effect of gender was significant for verbal learning and memory, wherein women outperformed men.
	Vaskinn et al., 2011 [72]	154 participants with schizophrenia and 106 participants with bipolar I disorder	Neurocognitive performance	Women performed better than men for all neuropsychological tests (except attention and working memory).

^*Sample characteristics of the participants with a psychotic spectrum disorder ^**key finding regarding gender differences.

RDC: research diagnostic criteria; DSM: diagnostic and statistical manual of mental disorder; CI: confidence interval; LTP: lifetime prevalence; PANSS: positive and negative syndrome scale; DAS: disability assessment scale; GAF: global assessment functioning; ICD: international classification of diseases; VIQ: substantial verbal intelligence quotient; PIQ: performance intelligence quotient.