Is there a sex-specific difference in onset age of schizophrenia that started before age 18?

Epidemiology of schizophrenia

OBJECTIVE

To characterize the epidemiology of schizophrenia.

METHOD

Narrative literature review.

RESULTS

Each year 1 in 10,000 adults (12 to 60 years of age) develops schizophrenia. Based on a restrictive and precise definition of the diagnosis and using standardized assessment methods and large, representative populations, the incidence rates appear stable across countries and cultures and over time, at least for the last 50 years. Schizophrenic patients are not born into ecological and social disadvantage. The uneven distribution of prevalence rates is a result of social selection: an early onset leads to social stagnation, a late onset to descent from a higher social status. The main age range of risk for schizophrenia is 20 to 35 years. It is still unclear whether schizophrenia-like late-onset psychoses (for example, late paraphrenia) after age 60 should be classified as schizophrenia either psychopathologically or etiologically. In 75% of cases, first admission is preceded by a prodromal phase with a mean length of 5 years and a psychotic prephase of one year's duration. On average, women fall ill 3 to 4 years later than men and show a second peak of onset around menopause. Consequently, late-onset schizophrenias are more frequent and more severe in women than in men. The sex difference in age of onset is smaller in cases with a high genetic load and greater in cases with a low genetic load. Type of onset and core symptoms do not differ between the sexes. The most pronounced sex difference is the socially negative illness behaviour of young men.

CONCLUSIONS

Among the factors determining social course and outcome are level of social development at onset, the disorder itself (for example, genetic liability, severity of symptoms, and functional deficits), general biological factors (for example, estrogen), and sex- and age-specific illness behaviour.

Epidemiology of early-onset schizophrenia

A total of 232 (84%) first episodes of schizophrenia from our epidemiologically defined ABC sample (Age, Beginning and Course) were retrospectively assessed with regard to the onset and early course of the disorder. In a follow-up study a representative subgroup (n = 133) was prospectively examined in five cross sections over 3 years from first admission on. Population-based incidence rates for 5-year age groups comprising a range of < 10 - < 60 years were calculated on the basis of two definitions of onset: first sign of disorder and first psychotic symptom. In 40% of adult patients who had been admitted with a first schizophrenic episode after age 20 years the prodromal phase, in 11% the psychotic prephase, began before that age. This demonstrates that schizophrenia often begins in an age period in which the social and cognitive development and brain maturation are still unfinished. Early-onset schizophrenias (< or = 20 years) were compared with a medium-onset group (21 - < 35 years) and a late-onset group (35 - < 60 years) with regard to age and type of onset, early symptom-related course, social development and social course. The number of schizophrenia-specific positive and negative syndromes in early-onset schizophrenia is comparable to that of higher age groups. However, neurotic syndromes, emotional disorders and conduct disorders are most frequent in younger patients, especially in young men. Paranoid syndromes seem to prevail in late-onset schizophrenia, whereas less differentiated positive syndromes, such as delusional mood, are more frequent in the youngest age group. An earlier onset of schizophrenia has more severe social consequences than onset in adults, because it interrupts the cognitive and social development at an earlier stage. The worse social course of schizophrenia in men compared with women cannot be related to a more severe symptomatology, but to the earlier age at onset and the impairment or stagnation of social ascent at an earlier stage of social and cognitive development. Social disability in the sense of an adaptation to the expectations of the social environment, as well as symptomatology during the further course of schizophrenia, show no major differences between the genders nor between the age groups.

Course of patients diagnosed as having schizophrenia during first episode occurring under age 18 years

Of 118 child and adolescent schizophrenic patients (ICD-9: 295.x; mean onset age 16.0 years), 97 (82.2%) could be completely investigated at follow-up (mean interval 7.4 years; mean age 23.1 years). At follow-up 30% of the patients were semi-dependent or dependent, 72% still required psychiatric treatment, 44% were at least moderately impaired with regard to educational/occupational functions and 58% with regard to social functions; 73% had experienced at least one further schizophrenic episode. Comparison with schizophrenia beginning in adulthood showed that the impairment in social function was much greater in the younger group of patients. These results support the belief that schizophrenic psychoses starting in adolescence have a worse outcome than those beginning in adulthood. The most efficient indicators for a worse outcome were long duration of inpatient treatment at first admission, a high number of symptoms and low social competence at discharge.