Examining psychotic experiences in two generations - Findings from a rural household-based cohort study; The Lolland-Falster Health Study

Background Psychotic disorders are highly heritable, yet the evidence is less clear for subclinical psychosis expression, such as psychotic experiences (PEs). We examined if PEs in parents were associated with PEs in offspring. Methods As part of the Danish general population Lolland-Falster Health Study, families with youths aged 11-17 years were included. Both children and parents reported PEs according to the Psychotic Like Experiences Questionnaire, counting only 'definite' PEs. Parents additionally reported depressive symptoms, anxiety, and mental wellbeing. The associations between parental and child PEs were estimated using generalized estimating equations with an exchangeable correlation structure to account for the clustering of observations within families, adjusting for sociodemographic characteristics. Results Altogether, 984 youths (mean age 14.3 years [s.d. 2.0]), 700 mothers, and 496 fathers from 766 households completed PEs-questionnaires. Offspring of parents with PEs were at an increased risk of reporting PEs themselves (mothers: adjusted risk ratio (aRR) 2.42, 95% CI 1.73-3.38; fathers: aRR 2.25, 95% CI 1.42-3.59). Other maternal problems (depression, anxiety, and poor mental well-being), but not paternal problems, were also associated with offspring PEs. In multivariate models adjusting for parental problems, PEs, but not other parental problems, were robustly associated with offspring PEs (mothers: aRR 2.25, 95% CI 1.60-3.19; fathers: aRR 2.44, 95% CI 1.50-3.96). Conclusions The current findings add novel evidence suggesting that specific psychosis vulnerability in families is expressed at the lower end of the psychosis continuum, underlining the importance of assessing youths' needs based on psychosis vulnerability broadly within the family systems.