Neuroprogression and Cognitive Functioning in Bipolar Disorder: A Systematic Review

Abstract

Bipolar disorder (BD) has been associated with impairments in a range of cognitive domains including attention, verbal learning, and mental flexibility. These deficits are increased during the acute phases of the illness and worsen over the course of BD. This review will examine the literature in relation to potential mechanisms associated with cognitive decline in BD. Scopus (all databases), Pubmed, and Ovid Medline were systematically searched with no language or year restrictions, up to January 2015, for human studies that collected cross-sectional and longitudinal cognitive data in adults with BD and matched healthy controls (HC). Selected search terms were "bipolar," "cognitive," "aging," "illness duration," "onset," and "progression." Thirty-nine studies satisfied the criteria for consideration. There is evidence that cognitive function in BD is negatively associated with features of illness progression such as number of mood episodes, illness duration, and hospitalizations. Aging does not appear to affect cognitive functioning to a greater extent than in HC. Furthermore, the small number of longitudinal studies in this field does not allow to reaching firm conclusion in terms of which sub-populations would be more prone to cognitive decline in BD. The decline in cognitive abilities over the course of the BD seems to be associated with the number of episodes and number of hospitalizations. No meaningful interaction of age and bipolar disorder has been found in terms of cognitive decline. Future large-scale longitudinal studies are necessary to confirm these findings and assist in the development of preventive interventions in vulnerable individuals.

Dynamic functional connectivity in bipolar disorder is associated with executive function and processing speed: A preliminary study.

“…Thus, aging is associated with a disruption and weakening of the coordinated activity between the anterior and posterior components of the DMN. A similar observation in our sample of BD patients hints at the possibility that BD may be associated with an underlying accelerated aging process (Cardoso, Bauer, Meyer, Kapczinski, & Soares, 2015; Rizzo et al, 2014). Although overall connectivity strength was preserved, reduced variability may be an early sign of age-related changes that precedes further disruption of these networks, contributing to cognitive decline.…”

Reversal-learning deficits in childhood-onset bipolar disorder across the transition from childhood to young adulthood

“…Thus, while we had a great deal of information about our participants, including age of BD illness onset and assessment for psychopathology, mood, and functioning at the time of CANTAB testing, we did not have prospective information for the child BD participants about number and duration of mood episodes prior to testing. Given that some, but not all studies suggest that clinical course influences cognitive performance, further work is needed using longitudinal studies assessing both psychopathology and cognitive performance (Cardoso et al, 2015; Dickstein et al, 2015a). Our lack of age effects or age-diagnosis interactions could also stem from cohort differences between our younger participants with BD and our older participants with BD.…”

History of Bipolar Disorder and the Risk of Dementia: A Systematic Review and Meta-Analysis

“…Several studies have shown that young and older adults with BD have significant cognitive impairment, especially with executive function and attentional processing, compared to age-matched control participants (2,3). The presence of cognitive impairment has been associated with greater disability, and it has been proposed that cognitive impairment may be a marker of neuroprogression (that is, a progressive condition that leads to cognitive impairment and dementia) in BD patients (4,5). Nonetheless, recent longitudinal studies do not corroborate this view since they failed to demonstrate accelerated cognitive decline in BD compared to age-matched controls, despite the fact that persons with BD performed worse than control participants at all study assessment points (6,7).…”