We studied the cumulative incidence of physical illnesses, and the effect of early environmental factors (EEFs) on somatic comorbidity in schizophrenia, in nonschizophrenic psychosis and among nonpsychotic controls from birth up to the age of 50 years.

The sample included 10,933 members of the Northern Finland Birth Cohort 1966, of whom, 227 had schizophrenia and 205 had nonschizophrenic psychosis. Diagnoses concerning physical illnesses were based on nationwide registers followed up to the end of 2016 and classified into 13 illness categories. Maternal education and age, family type at birth and paternal socioeconomic status were studied as EEFs of somatic illnesses.

When adjusted by gender and education, individuals and especially women with nonschizophrenic psychosis had higher risk of morbidity in almost all somatic illness categories compared to controls, and in some categories, compared to individuals with schizophrenia. The statistically significant adjusted hazard ratios varied from 1.27 to 2.42 in nonschizophrenic psychosis. Regarding EEFs, single-parent family as the family type at birth was a risk factor for a higher somatic score among men with schizophrenia and women with nonschizophrenic psychosis. Maternal age over 35 years was associated with lower somatic score among women with nonschizophrenic psychosis.

Persons with nonschizophrenic psychoses have higher incidence of somatic diseases compared to people with schizophrenia and nonpsychotic controls, and this should be noted in clinical work. EEFs have mostly weak association with somatic comorbidity in our study.

Psychotic depression (PD) is heavily understudied despite high mortality and the severe course of illness. A majority of the studies conducted so far are also largely based on selected clinical samples. The aim of this study was to examine the clinical characteristics of PD in a representative prospective birth cohort sample.

The Northern Finland Birth Cohort 1966 is a well-known prospective population-based cohort including 12 058 people followed since mid-pregnancy. We identified 55 individuals with PD, analysed their characteristics and compared them with schizophrenia (SZ), non-psychotic depression (NPD), psychotic bipolar disorder (PBD) and other psychoses (PNOS).

The life-time prevalence of stable (no conversion to schizophrenia, bipolar disorder or schizoaffective disorder) PD was 0.5%. PD subjects were older than SZ and PNOS subjects during the first psychotic episode and compared to SZ, more often female. PD required hospitalization and transition to disability pension more often than NPD, but less often than SZ. Comorbid alcohol abuse disorder (44%) and personality disorder (40%) were highly common in PD. PNOS had a similar occupational outcome than PD but hospitalization rate was lower in the PNOS group. PBD and PD had mostly comparable outcomes.

Our findings in a naturalistic cohort support the notion that the course of illness in PD is mostly similar to that of PBD, it is less severe than in schizophrenia, but worse than in non-psychotic depression. PD seems to have high psychiatric comorbidity.

The association between cannabis use and the risk of psychosis has been studied extensively but the temporal order still remains controversial.

To examine the association between cannabis use in adolescence and the risk of psychosis after adjustment for prodromal symptoms and other potential confounders.

The sample (n = 6534) was composed of the prospective general population-based Northern Finland Birth Cohort of 1986. Information on prodromal symptoms of psychosis and cannabis use was collected using questionnaires at age 15–16 years. Participants were followed up for ICD-10 psychotic disorders until age 30 years using nationwide registers.

The risk of psychosis was elevated in individuals who had tried cannabis five times or more (hazard ratio, (HR) = 6.5, 95% CI 3.0–13.9). The association remained statistically significant even when adjusted for prodromal symptoms, other substance use and parental psychosis (HR = 3.0, 95% CI 1.1–8.0).

Adolescent cannabis use is associated with increased risk of psychosis even after adjustment for baseline prodromal symptoms, parental psychosis and other substance use.

None.