A comparison of the cumulative incidence and early risk factors for psychotic disorder in young adults in the Northern Finland Birth Cohorts 1966 and 1986

Abstract

Aims. Few studies have compared time trends for the incidence of psychosis. To date, the results have been inconsistent, showing a decline, an increase or no significant change. As far as we know, no studies explored changes in prevalence of early risk factors. The aim of this study was to investigate differences in early risk factors and cumulative incidences of psychosis by type of psychosis in two comparable birth cohorts.Methods. The Northern Finland Birth cohorts (NFBCs) 1966 (N = 12 058) and 1986 (N = 9432) are prospective general population-based cohorts with the children followed since mother's mid-pregnancy. The data for psychoses, i.e. schizophrenia (narrow, spectrum), bipolar disorder with psychotic features, major depressive episode with psychotic features, brief psychosis and other psychoses (ICD 8-10) were collected from nationwide registers including both inpatients and outpatients. The data on early risk factors including sex and place of birth of the offspring, parental age and psychosis, maternal education at birth were prospectively collected from the population registers. The follow-up reached until the age of 27 years.Results. An increase in the cumulative incidence of all psychoses was seen (1.01% in NFBC 1966 v. 1.90% in NFBC 1986; p < 0.001), which was due to an increase in diagnosed affective and other psychoses. Earlier onset of cases and relatively more psychoses in women were observed in the NFBC 1986. Changes in prevalence of potential early risk factors were identified, but only parental psychosis was a significant predictor in both cohorts (hazard ratios ≥3.0; 95% CI 1.86-4.88). The difference in psychosis incidence was not dependent on changes in prevalence of studied early risk factors. Conclusions. Surprisingly, increase in the cumulative incidence of psychosis and also changes in the types of psychoses were found between two birth cohorts 20 years apart. The observed differences could be due to real changes in incidence or they can be attributable to changes in diagnostic practices, or to early psychosis detection and treatment.

Smokin‘ hot: adolescent smoking and the risk of psychosis

“…The strengths of this study include the study sample, the NFBC 1986 is one of the largest birth-cohort studies with high genetic and ethnic homogeneity; the considerable number of daily smokers in the study allowing robust examination of the associations and the dose-response relationship and the use several nationwide registers combined with a very small proportion of cohort members deceased or emigrated during the follow-up. Therefore, the coverage of clinically significant psychosis diagnoses within this population during the 15-year follow-up can be considered high (16). Indeed, the incidence rate in this sample was 121 per 100 000 per year, which is significantly higher than in most of the previous samples (29)(30)(31).…”

“…The statistical analyses for logistic and Cox regression analyses were performed using SPSS 23.0 and the inverse probability of treatment weighting analyses were carried out using R 3.3.2 with packages mice (2.25), survival (2.40-1), and boot (1. [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18].…”

“…Information on diagnosed psychoses (ICD-10: (16). Age at the time when psychosis was first detected was estimated as the onset age of psychosis.…”

“…Family structure at birth and in adolescence. Information on family structure was gathered from self-reports that were collected from parents at birth and when the cohort member was aged [15][16]. Subjects that were living with their primary family from birth to adolescence (i.e., living with subject all the time) were classified as (1) 'intact families' and all the others as (2) 'non-intact families'.…”

Parental hospital‐treated somatic illnesses and psychosis of the offspring—The Northern Finland Birth Cohort 1986 study

“…Psychoses (ICD-9: 2950-2959, 2961E, 2962E, 2963E, 2964E, 2967, 297, 2988, 2989; ICD-10: F20-F25, F28, F29, F302, F312, F315, F323, F333) of cohort members diagnosed between the ages of 16 and 28 y, and parental psychiatric morbidity (ICD-8/9: 290-319, ICD-10: F-codes) when the offspring was under 18 y of age, were defined to be present if found from the following Finnish national registers: Care Register for Health Care (CRHC) (inpatient treatments 1969-2013), Finnish outpatient registers (outpatient visits in specialized care 1998-2013, primary care 2011-2013), Social Insurance Institution registers (parents' reimbursable medicines from the offspring's birth until 2005) and Finnish Centre for Pensions (parents' disability pensions from the offsprings' birth until 2013) (Filatova et al, 2017). The Finnish national registers have been shown to be valid tools for scientific research (Miettunen, Suvisaari, Haukka, & Isohanni, 2011).…”