Sex difference in age at onset of schizophrenia

The age at onset of schizophrenia was determined in 100 male and 100 female patients who unequivocally met DSM-III criteria for the illness. Three different indexes of onset were used: first treatment, first hospitalization, and the immediate family's first awareness of psychotic symptoms and signs. The mean age at onset of the male patients was approximately five years earlier than that of the female patients according to all three criteria. About nine of ten male patients, compared with only two of three female patients, became schizophrenic before the age of 30 years. The onset of psychosis after the age of 35 years occurred in 17% of women and in only 2% of men. About 10% of women gave no evidence of psychosis until after the age of 40 years. The reason for the sex difference is not readily apparent, but it could be a valuable clue to some of the causes of schizophrenia.     

The impact of familial loading on gender differences in age at onset of schizophrenia

To evaluate the impact of familial loading and gender on age at onset, 197 schizophrenic patients were investigated. Patients with familial loading had an earlier age at onset without gender differences. In contrast, an earlier age at onset for men was found in sporadic cases. These data support that both gender and familial loading contribute to the heterogeneity of schizophrenia.     

A typological model of schizophrenia based on age at onset,sex and familial morbidity

We investigated the age at onset distributions of schizophrenia in men and women and the relationship of age at onset and sex to the familial rates of schizophrenia and manic-depression in data from a Swedish family study of 270 schizophrenic probands. On the logarithmic scale, the age at onset distribution of schizophrenia in both male and female relatives was bimodal, suggesting that broadly defined schizophrenia may be a mixture of 2 (probably related) disorders. The risk of schizophrenia in relatives decreased as a function of the age at onset of the proband, irrespective of the sex of the proband or relative. In contrast, the risk of manic-depression was significantly higher in relatives of female probands with an age at onset in the twenties than in relatives of female probands with earlier or later onset, or in relatives of male probands. This suggests a third disorder related to affective psychosis, with an intermediate age at onset and female preponderance.     

Schizophrenia: age at onset, gender and familial risk

In a family history study of 366 schizophrenic probands and their 1851 first-degree relatives, we found a relationship between age at onset of psychosis in the male probands and the risk for schizophrenia in their relatives. The relatives of male schizophrenic probands whose onset of psychosis occurred when they were younger than 17 years of age had an increased risk of schizophrenia when compared with the relatives of male probands with an age at onset greater than 17. We did not find an association between age at onset of psychosis in the female probands and familial risk. Cox proportional hazards models permitted us to examine the relationship between age at onset of psychosis in the probands and familial risk while controlling for possible confounding effects.     

Gender and schizophrenia: age at onset and sociodemographic attributes.

A consecutive series of 214 patients (125 males, 89 females) who met the Research Diagnostic Criteria for schizophrenia were studied to determine gender differences in age at onset of the illness and sociodemographic attributes. The immediate family's first awareness of psychotic symptoms or signs and age at first presentation in hospital were used as indices of onset; male patients had a significantly earlier age of onset than females. By the time they were 30 years of age, 83% of male patients had already become ill and only 66% of females had done so. Significantly more females than males were married at the time of first contact with hospital. Married males did not differ from married females in age at onset of illness, suggesting that patients who marry may have late onset.     

Influence of Sex on Age at Onset of Schizophrenia

Abstract: The age at onset of schizophrenia was investigated in 2,417 inpatients (1,433 males and 984 females) meeting the DSM-III criteria for schizophrenia. About 80% of the patients became schizophrenic before the age of 30. The mean age at onset of the male patients was slightly earlier than that of the female patients. There was a higher cumulative percentage of the male patients who became affected at each age quinquennium. More men than women became schizophrenic before the age of 30.     

Does family history of schizophrenia influence age at onset of schizophrenia?

The relation between age at onset of schizophrenia diagnosed using DSM-III criteria and the presence or absence of this illness among first-degree relatives was investigated in 2417 patients. The mean age at onset among those with a family history of schizophrenia was slightly and nonsignificantly earlier than that of schizophrenic patients without a positive family history. The former developed their illness before the age of 25 years more frequently than did the latter.     

Age at onset of schizophrenia: gender differences and influence of temporal socioeconomic change

This study was undertaken to examine whether males develop schizophrenia at a younger age than females, and whether temporal socioeconomic change affects the age at onset of schizophrenia. The subjects were 848 ICD-9 schizophrenics who were admitted to Nihon University Hospital, Tokyo, Japan, during the period of 1955-64 (n = 468 (214 males and 254 females), group A) or during the period of 1982-91 (n = 380 (220 males and 160 females). group B). Schizophrenic males showed an earlier age at onset than schizophrenic females. However, the mean age at onset of schizophrenia did not differ significantly between group A and group B. These results indicate that the gender difference in age at onset of schizophrenia has not been influenced by temporal socioeconomic change.     

Gender- and age-dependent differences in latent inhibition following pre-weaning non-handling : implications for a neurodevelopmental animal model of schizophrenia

Latent inhibition (LI) refers to retarded conditioning to a stimulus as a consequence of its prior nonreinforced pre-exposure, and is considered to index the capacity of an organism to ignore irrelevant stimuli. LI disruption has received increasing attention as an animal model of the widely described attentional deficit of schizophrenia, consisting of an inability to ignore irrelevant stimuli. The present experiments investigated the effects of infantile manipulations on the development of LI. Male and female rats handled or nonhandled in infancy (days 1–22), were tested at 3 and 16 months. Young handled animals had lower emotional reactivity than nonhandled, and this difference persisted in females at 16 months. At 3 months, LI, poorer conditioning of stimulus pre-exposed as compared to nonpre-exposed rats, was obtained in handled and nonhandled females, as well as in handled males, but was absent in nonhandled males. This pattern changed at 16 months : both nonhandled males and females failed to show LI. These gender- and age-dependent effects of pre-weaning manipulations on LI loss may provide an animal parallel to the susceptibility of young adult males to schizophrenia and the attenuation of gender differences in long-term outcome schizophrenia.     

Sex difference in the regeneration of the hypoglossal nerve in rats

Sex difference in the rate of regeneration of the hypoglossal nerve was demonstrated in rats. A significantly larger number of the regenerating fibers reached the tongue earlier in males than in females or castrated males. These data provide evidence that testosterone, endogenous or administered, plays an importanta role in promoting nerve regeneration.     

An analysis of the clinical features of familial schizophrenia

Clinical features of familial schizophrenia were examined in 169 siblings from 80 families. Factor analysis of symptoms produced a negative symptom factor (affective flattening and negative thought disorder), a disorganization factor (inappropriate affect and positive thought disorder) and a reality distortion factor (delusions and hallucinations). The negative symptom factor correlated positively with duration of illness and poor outcome. The disorganization factor correlated positively with poor outcome and early age at onset. The only clear correlation between these factors and affective symptoms was a negative one between the negative symptom factor and mania. There were no significant gender differences in age at onset, factor scores or outcome. The implication of these findings in relation to recent research in the areas of psychopathology and epidemiology are discussed.     

Sex difference in the prevalence of smoking in Chinese schizophrenia

Despite a large proportion of smoker in Chinese population, few studies address the prevalence of smoking in schizophrenia in such a homogeneous ethnic group. This study examined gender-specific relationships between smoking and schizophrenia, which have previously received little systematic study. The prevalence of smoking in 510 inpatients with schizophrenia and 793 normal controls was evaluated. The relationships between smoking and retrospectively assessed measures of the course of schizophrenia were evaluated by clinician-administered questionnaires. The results showed that the gender difference in smoking prevalence was in the opposite direction for males compared to females between schizophrenia and normal controls. Male patients had a higher smoking rate than controls (81% vs 66%, adjusted OR = 2.3, p < 0.0001), while female patients had a lower rate than controls (5% vs 9% p > 0.05). Smoking was associated with a family history of smoking, a personal history of alcohol use and age in men with schizophrenia. Our present findings suggest a significant gender difference in the prevalence of smoking in schizophrenia.     

慢性精神分裂症患者生命质量的性别差异

目的：探讨长期住院的慢性精神分裂症患者生命质量的性别差异及影响因素。方法：采用健康状况调查问卷（SF-36）、阳性与阴性症状量表（PANSS）、治疗中出现的症状量表（TESS）对连续住院时间超过5年的72例男性、47例女性慢性精神分裂症患者进行评定,选用60名健康自愿者作为对照。结果：男性患者生命质量显菩低于女性;精神病状态、药物种类、药物不良反应、年龄、住院时间对男女生命质量均有影响;男性的生命质量还受病期、婚姻状况的影响。结论：慢性精神分裂症患者的生命质量低下．应给予更多关注。     

Decline in diagnoses of schizophrenia in Tasmania during the period 1965–1990

Changes in the rates of diagnosis of schizophrenia in Tasmania, Australia during the period 1965–1990 were examined using records from the State mental health case register. Analyses were restricted to subjects with diagnoses recorded between the ages of 20 and 29 years in order to reduce possible errors caused by age-standardized methods. There was a significant decrease in the rate of non-paranoid subtypes of schizophrenia in female subjects, accompanied by a, commensurate rise in the rate of bipolar diagnoses in that group. Differential changes in male and female subjects support explanations of phenotypic shifts in presentation of psychosis as well as changes in diagnostic practice.     

Admixture analysis of age at onset in schizophrenia

In schizophrenia, clinical, familial and biological characteristics according to age at onset (AAO) suggest that AAO is a valid candidate symptom for genetic studies. However, none of the various thresholds used to define AAO subgroups in schizophrenia has been validated. We aim to define different AAO subtypes by admixture analysis in a sample of prospectively recruited subjects with schizophrenia. Consecutive inpatients and outpatients (N=141) meeting DSM IV criteria for schizophrenia were included. We used admixture analysis to investigate whether the observed AAO distribution consisted of a mixture of gaussian distributions and then compared clinical features and familial risks in the various groups of subjects. The model that best fitted the observed AAO distribution was a mixture of two gaussian distributions (mean+/-S.D.): (19.91+/-3.56 years) and (33.48+/-8.2 years), with a cutoff point at 28 years. The existence of two subgroups according to AAO was further confirmed by the different clinical and familial profiles of these subgroups. The early-onset group consisted predominantly of male patients, with non-paranoid subtypes and with a higher familial risk of schizophrenia spectrum disorders and affective disorders. The late-onset group of patients presented predominantly paranoid subtype, preponderance of females; they were more likely to be married and to have children. We identified two subgroups of schizophrenic subjects with different clinical and familial profiles. This study provides a mathematical validation of the existence of two subgroups defined by an onset of schizophrenia before or after 28 years. These results may have important implications for the search for schizophrenia susceptibility factors. Working with homogeneous subgroups defined on the basis of AAO may facilitate the identification of genetic vulnerability factors in schizophrenia.     

Sex difference in prevalence of minor psychiatric morbidity: a social epidemiological study in Taiwan

The female excess in prevalence of minor psychiatric morbidity (MPM) evident in a community study in Taiwan (n = 1023) was further investigated in terms of demographic variables, socioenvironmental risk factors and psychosocial stresses. It was suggested that a stronger effect of chronic psychosocial stressors accounted for the higher prevalence of MPM in women. Further analysis has revealed a longer mean duration of MPM in women and an incidence ratio close to unity between the sexes. These retrospective findings were further examined in a small one-year prospective outcome study; a poorer outcome was found among older subjects and female subjects. It is suggested that more females have MPM because chronic psychosocial stressors more adversely affect the course of such morbidity. These results are discussed in a cross-cultural context.     

Familial-genetic and reproductive epidemiology of schizophrenia in rural Ireland: age at onset,familial morbid risk and parental fertility

Waddington JL and Youssef HA. Familial-genetic and reproductive epidemiology of schizophrenia in rural Ireland: age at onset, familial morbid risk and parental fertility Acta Psychiatr Scand 1996: 93: 62–68. © Munksgaard 1996. Among all ascertainable cases of DSM IIIR schizophrenia within an unusually homogeneous region of rural Ireland, family history information was sought from multiple sources. Morbid risk for schizophrenia among probands' first degree relatives was 6.1% and did not differ between male (6.5%) and female (5.5%) probands; risk among probands' siblings (8.3%) exceeded that among their parents (1.4%), with only 2% of male and 31% of female probands being themselves married. Both age at onset <25 and having >7 siblings were associated with elevated morbid risk, particularly among relatives of male probands (11.9% vs. 2.2% and 11.8% vs. 3.7%, respectively). Increased fertility particularly among parents of male patients with high familial-genetic loading may contribute to perpetuation of the disorder in the face of those patients' own extremely low fecundity.