Influence of cognitive reserve on neuropsychological functioning in bipolar disorder: Findings from a 5-year longitudinal study.

OBJECTIVES: The present study examined the 5-year longitudinal course of cognitive functioning in a large sample of well-characterized patients with bipolar disorder (BP), compared to healthy controls (HCs), and the influence of cognitive reserve factors (e.g., education and IQ) on cognitive change over time. METHODS: Participants included 159 individuals diagnosed with BP and 54 HCs recruited as part of a longitudinal naturalistic study of BP who had completed neuropsychological testing at the time of their enrollment and again 5 years later. RESULTS: The overall relative rate of change did not differ between the BP and HC groups. In total, 46.5% of the BP group and 37% of the HC group showed evidence of decline on at least one measure over time. T-test analyses did not find differences between BP 'decliners' and 'non-decliners' in cognitive reserve variables. However, we found that higher baseline intellectual ability was associated with more stability in cognitive test scores over time for the BP group. Results of linear regression modeling revealed that lower verbal IQ and education were related to increased cognitive decline in specific domains in the BP group. CONCLUSIONS: This study has explored the influence of cognitive reserve on preservation of specific cognitive abilities over time in BP. The BP group did not demonstrate accelerated cognitive decline over 5 years compared to the HC group. Although the trajectory of cognitive change over time was similar between BP patients and HCs, higher overall intellectual ability may be a protective factor against cognitive decline, particularly for BP patients.

Cognitive reserve and executive function: Effect on judgment of health and safety.

Individuals with the same neurological conditions do not necessarily manifest the same behavioral presentation, which suggests differences in resilience and vulnerability among individuals, a concept known as cognitive reserve. This study sought to explore the relationship among cognitive reserve, executive functioning, and health and safety judgment among a sample of older adult inpatients in an extended medical care unit at a Veterans Health Administration hospital. We hypothesized that cognitive reserve, as determined by an estimate of premorbid intellectual ability, would act as a protective factor against poor judgment in older adults with executive dysfunction. Participants included 200 Veterans who completed a comprehensive neuropsychological assessment, including measures of health and safety judgment, executive functioning, global cognitive functioning, and premorbid intellectual ability. After controlling for global cognitive functioning, executive functioning abilities did not have an effect on judgment abilities among those with high estimated intellectual ability. However, executive functioning had a significant effect on judgment abilities among those with low estimated intellectual ability. Our results suggest that intact executive functioning is critical for making appropriate health and safety decisions for patients with lower measured intellectual abilities and provide further support for the cognitive reserve model. Clinical implications are also discussed.