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Jaana Suvisaari

Publications and source records attributed to Jaana Suvisaari.

4 recordsLinked to original sources
PubMed2003

Increasing age does not decrease risk of schizophrenia up to age 40.

It is well established that at the population level the age-specific incidence of schizophrenia is highest in the early 20s and decreases with age. We present new findings showing that this is not the case when we assume that only part of the population is susceptible. The study population consisted of birth cohorts born in Finland from 1950 to 1968. These were identified from the Population Register Center, which provided the data as multidimensional tables with sex, and year, month, and place of birth as marginals. Each cohort was followed-up until 1991, up to age 40. Data analyses were based on a compound Poisson statistical model, which assumed that only part of the population is susceptible to develop schizophrenia. The method detects the proportion of susceptibles in population level, but does not identify susceptible individuals. The model was able to reveal the basic hazard distribution, which showed increasing risk of developing schizophrenia with higher age at the individual level among the susceptible part of the population. The increase in risk was more rapid among males, but the susceptible part of the population was of similar size among both sexes. The proportion of susceptibles seemed to be lower in younger cohorts. We conclude that when an individual belongs to the susceptible part of the population, his/her individual risk of developing schizophrenia increases with age, at least up to age 40. This increase is more rapid among males. The reasons behind the lower proportion of susceptibles in younger birth cohorts, as well reasons for differences in risk between sexes remained unclear and need more research.

Adult↗
PubMed2003

Fertility of patients with schizophrenia, their siblings, and the general population: a cohort study from 1950 to 1959 in Finland.

OBJECTIVE: Genetic factors are the most important risk factors for schizophrenia. However, despite the fact that patients with schizophrenia have significantly fewer offspring than the general population, schizophrenia persists. The authors investigated whether the siblings of patients with schizophrenia produce more offspring, thereby compensating for the low fertility of the affected individuals. METHOD: From all 870,093 individuals born in Finland from 1950 to 1959, the authors determined how many had schizophrenia or were siblings of schizophrenia patients and how many offspring they had. The population data were obtained from the Population Register Center of Finland, and the National Hospital Discharge Register was used to identify all persons who had been hospitalized because of schizophrenia. Appropriate regression models were used to model age at the birth of the first child, number of children, and proportion of males among offspring. RESULTS: Of the total population, 1.3% were patients with schizophrenia, and 2.8% were their siblings. The mean number of offspring among female siblings was slightly but significantly higher than among women in the general population (1.89 versus 1.83), while the opposite was true for the male siblings (1.57 versus 1.65 among men in the general population). The mean number of offspring among patients with schizophrenia was 0.83 for women and 0.44 for men. CONCLUSIONS: Lower than average fertility among patients with schizophrenia is not compensated for by higher fertility among their siblings. Thus, the persistence of schizophrenia in the general population is not explained by this simple evolutionary mechanism.

Adult↗
PubMed2003

Childhood central nervous system viral infections and adult schizophrenia.

OBJECTIVE: An earlier Finnish cohort study suggested that childhood viral CNS infections are associated with a fivefold increased odds of developing schizophrenia in adulthood. The authors sought to replicate this finding. METHOD: From the archives of the Department of Virology of the National Public Health Institute in Finland, 320 individuals born between 1960 and 1976 who had suffered virologically confirmed CNS infections before their 15th birthdays were identified. Of the infections, 202 had been caused by enteroviruses. The sample was followed up in the 1969-2000 records of the National Hospital Discharge Register of Finland to identify all cases of schizophrenia that emerged. RESULTS: The cumulative incidence of schizophrenia was 0.94% in the whole sample and 0.99% among individuals who had suffered enteroviral infections. These rates are comparable to that found in the general population. CONCLUSIONS: Childhood viral CNS infections were not associated with increased risk of schizophrenia.

Adolescent↗