Fine motor skill and processing speed deficits in young people with psychotic experiences: A longitudinal study

To identify neuropsychological and motor changes from adolescence to early adulthood in young people with psychotic experiences (PE).

A community-based sample of 56 young people attended the study over a 9 year follow-up period. Participants were assessed over 3 time-points at T1, T2 and T3 aged x¯ = 11.69, x¯ = 15.80 and x¯ = 18.80 years respectively. PE were assessed using the Kiddie Schedule for Affective and Depressive Symptoms (K-SADS). Neuropsychological assessments, including subtests of the MATRICS battery, and motor assessments were examined at T2 and T3. Two groups were compared: those who ever reported PE during their adolescence or early adulthood (n = 21) and a healthy control group (n = 35). Further group analysis was conducted within the PE group subdividing into those with transient PE (n = 10) and those with persistent PE (n = 11).

At T3, a significant group difference was found between the PE and control groups in the fine motor skill task, the Pegboard task (F = 4.8, p = .03) and the processing speed task, the Digit-Symbol Coding task (F = 5.36, p = .03). Furthermore, a significant group difference was found between the transient PE and control groups on the Digit-Symbol Coding task (F = 5.61, p = .02), while a significant group difference was found between the persistent PE and control groups on the Pegboard task (F = 7.84, p = .01).

This study shows that fine motor skill and processing speed deficits persist in young people who report PE, even in those with transient PE. The current research advances the knowledge about the trajectory and precursors of sub-clinical symptoms of psychosis in young people.