A review of the cognitive impact of neurodevelopmental and neuropsychiatric associated copy number variants

The heritability of intelligence or general cognitive ability is estimated at 41% and 66% in children and adults respectively. Many rare copy number variants are associated with neurodevelopmental and neuropsychiatric conditions (ND-CNV), including schizophrenia and autism spectrum disorders, and may contribute to the observed variability in cognitive ability. Here, we reviewed studies of intelligence quotient or cognitive function in ND-CNV carriers, from both general population and clinical cohorts, to understand the cognitive impact of ND-CNV in both contexts and identify potential genotype-specific cognitive phenotypes. We reviewed aggregate studies of sets ND-CNV broadly linked to neurodevelopmental and neuropsychiatric conditions, and genotype-first studies of a subset of 12 ND-CNV robustly associated with schizophrenia and autism. Cognitive impacts were observed across ND-CNV in both general population and clinical cohorts, with reports of phenotypic heterogeneity. Evidence for ND-CNV-specific impacts were limited by a small number of studies and samples sizes. A comprehensive understanding of the cognitive impact of ND-CNVs would be clinically informative and could identify potential educational needs for ND-CNV carriers. This could improve genetic counselling for families impacted by ND-CNV, and clinical outcomes for those with complex needs.

Current psychosocial stress, childhood trauma and cognition in patients with schizophrenia and healthy participants

BACKGROUND

Cognitive difficulties are experienced frequently in schizophrenia (SZ) and are strongly predictive of functional outcome. Although severity of cognitive difficulties has been robustly associated with early life adversity, whether and how they are affected by current stress is unknown. The present study investigated whether acute stress reactivity as measured by heart rate and mood changes predict cognitive performance in patients with schizophrenia and healthy individuals, and whether this is moderated by diagnosis and previous childhood trauma exposure.

METHODS

One hundred and four patients with schizophrenia and 207 healthy participants were administered a battery of tasks assessing cognitive performance after psychosocial stress induction (Trier Social Stress Test; TSST). Mood states (Profile of Mood States; POMS) and heart rate were assessed at baseline, immediately before, and after the TSST.

RESULTS

Both healthy participants and patients showed increases in POMS Tension and Total Mood Disturbance scores between Time Point 2 (pre-TSST) and Time Point 3 (post-TSST). These changes were not associated with variation in cognition. Although childhood trauma exposure was associated with higher stress reactivity and poorer cognitive function in all participants, childhood trauma did not moderate the association between stress reactivity and cognition. Neither was diagnosis a moderator of this relationship.

DISCUSSION

These findings suggest that while chronic stress exposure explains significant variation in cognition, acute stress reactivity (measured by changes in Tension and Total Mood Disturbance) did not. In the context of broader developmental processes, we conclude that stressful events that occur earlier in development, and with greater chronicity, are likely to be more strongly associated with cognitive variation than acute transient stressors experienced in adulthood.