Season of birth and schizophrenia: Sex difference

Season of birth in females with anorexia nervosa in Northeast Scotland

“…Anorexia nervosa is predominantly a female condition, whereas tightly defined schizophrenia is more common in men in whom the onset tends to be earlier and the course less favorable (Lewis, 1992). There is also evidence that female fetuses are more at risk of developing schizophrenia after exposure to intrauterine influenza (Murray, Jones, O'Callaghan, Takei, & Sham, 1992;Takei et al, 1994;Izumoto et al, 1999) and that the winter-spring excess of births is greater among females than among males (Murray et al, 1992;Dassa, Azorin, Ledoray, Sambuc, & Giudicelli, 1996). It is tempting to speculate that common etiological factors operating in utero may increase the risk of both schizophrenia and anorexia nervosa, that such factors are more virulent to female than to male fetuses (or that female fetuses survive the neurodevelopmental stressor whereas male fetuses do not), and that the virulence of such factors may diminish with a "transmutation" of schizophrenia into anorexia nervosa, giving rise to the changes in incidence mentioned above.…”

Season of birth, gender and negative symptoms in schizophrenia

“…They also exhibit more affective symptoms and less severe negative symptoms and cognitive deficits, with lesser structural brain abnormalities (see [19] for a recent review). Also, the season-of-birth effect appears to be more significant in female than in male schizophrenia [5,7,28]. This finding has been tentatively explained by hypothesizing a greater vulnerability of women to seasonally varying environmental factors.…”

“…Based on this hypothesis, many studies have compared winter-and non-winter-born schizophrenic patients on a variety of variables including gender [1,11,28], place of birth (i.e., urban vs rural) [24], family history of mental disorder [7,25], electrodermal activity [14], ventricular enlargement [9,32], neuropsychological impairment [12], clinical subtype [10,13,18], and symptom profile [8,20,26,31].…”

“…In addition, we aimed to evaluate the effect of the season of birth on other clinical variables that had been already examined in previous studies. Since there is evidence that the season-of-birth effect in schizophrenia might be more pronounced in, or restricted to, women [5,7,28], gender-specific analyses were conducted.…”

Prenatal illness and subtypes of schizophrenia: The winter pregnancy phenomenon

“…Some associate this risk factor with the high number of winter-related viruses, particularly influenza, which can interfere with normal fetal brain development (Dassa, Azorin, Ledoray, Sambuc et al, 1996).…”