Intellectual Functioning in Offspring of Parents with Bipolar Disorder: A Review of the Literature.

Bonnie Klimes-Dougan,Jake Jeong,Timothy Allen,Kevin Kennedy

doi:10.3390/brainsci7110143

Abstract

Impaired intellectual functioning is an important risk factor for the emergence of severe mental illness. Unlike many other forms of mental disorder however, the association between bipolar disorder and intellectual deficits is unclear. In this narrative review, we examine the current evidence on intellectual functioning in children and adolescents at risk for developing bipolar disorder. The results are based on 18 independent, peer-reviewed publications from 1980 to 2017 that met criteria for this study. The findings yielded no consistent evidence of lower or higher intellectual quotient (IQ) in offspring of parents diagnosed with bipolar disorder. Some tentative evidence was found for lower performance IQ in offspring of bipolar parents as compared to controls. It is recommended that future research examine variability in intellectual functioning and potential moderators. These findings demonstrate the need to examine how intellectual functioning unfolds across development given the potential role of IQ as a marker of vulnerability or resilience in youth at high risk for affective disorders.

Highlights

Intellectual resources provide numerous advantages for the developing individual
There was considerable variability in the demographic variables reported for each study, but overall the BDO and the comparison group (CO) were similar
It was common for the range of ages for offspring to be broad, but on average offspring were in middle to late adolescence

Summary

Introduction

Intellectual resources provide numerous advantages for the developing individual. High intelligence is associated with increased self-control, social competence, academic and occupational success, mental health literacy, and longevity [1,2,3,4,5,6,7,8,9]. High intelligence serves as a protective factor against mental illness, whereas low premorbid intellectual functioning is a risk factor for many forms of serious psychopathology, including severe depression, schizophrenia, and other nonaffective psychoses [1,10,11,12]. Cognitive deficits are over-represented in those suffering from mental disorders [13,14,15] and are typically associated with a worse prognosis [16,17]. Unlike many other forms of mental disorder the relationship between bipolar disorder and intellectual deficits is unclear. In contrast to the more typical pattern of low intellectual functioning co-aggregating with severe mental illnesses, epidemiological studies using population-based cohorts, birth cohorts, and military conscripts have not consistently shown intellectual impairment in those at risk for or diagnosed with bipolar disorder.

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