A Longitudinal study of neurocognitive deficits and functional outcome in bipolar disorder

Bipolar disorder is an affective disorder that, in addition to being characterized by depressive and expansive mood symptoms, often presents with neuropsychological deficits. Bipolar disorder not only impairs an individual’s cognitive abilities, but these cognitive impairments may also impact day-to-day activities causing functional impairment. In other psychiatric disorders such as schizophrenia, it has been shown that the neuropsychological deficits are predictive of poor, long term treatment outcome and functioning. However, while bipolar disorder affects nearly 1 - 2% of the U.S. population (Keck, McElroy, & Arnold, 2001), little is known about the extent that neurocognitive deficits may play in the functional deficits experienced by those with bipolar disorder. Further, the research that does exist to examine this relationship has a number of limitations, including that it does not address longitudinal changes in cognition and function. These investigations also lack a comprehensive measure of either neurocognitive functioning or functional outcome. The current study employed a longitudinal design in which symptoms, functional outcomes and neurocognitive abilities were evaluated on two separate occasions separated by approximately 12 months from the first assessment (M = 11.86, SD = 4.47) . The primary goals of the study was to determine the extent to which neurocognitive abilities can predict functional outcomes over the long term, with a secondary goal to examine the stability of neurcognitive deficits over time. Assessment of neurocognitive abilities emphasized the domains of verbal learning and memory, visual learning and memory, executive functioning and visioconstruction/spatial abilities measured through the application of standardized neuropsychological instruments. Further, evaluation of symptoms and functional outcomes were accomplished using psychometric measures. It was predicted that neurocognitive abilities measured at the first evaluation would predict functional outcomes at the second evaluation, such that impaired neurocognitive functioning would predict poorer performance in functional measures (i.e. self-report measures of life-functioning and quality of life, as well as demand based functional tasks) and vice-versa. Further, it is predicted that some neurocognitive abilities would evidence improvement from evaluation 1 to evaluation 2, while others will not. The ability to predict long-term functioning, based upon acute neurocognitive abilities has important implications for treatment planning and implementation