Bipolar disorder is a disabling and costly mental illness. The number of elderly mentally ill individuals will increase rapidly in the coming decades, yet there has been little research focused on geriatric bipolar patients. In particular, little is known about changes in brain structure and function due to aging that may underlie worsening cognition. NIMH has recognized this unfortunate gap, and PA-07-077 calls for """"""""new research...
aim ed at delineating the neural circuitry...involved in late-life mood and anxiety disorders."""""""" Combining clinical and neuroscience expertise and cutting-edge technologies, the proposed study, led by a new investigator, aims to (1) investigate age-related differences in the structure, function, and connectivity of the prefrontal cortex (PFC) in bipolar disorder and whether these differences are greater than would be expected due to normal age-related changes, (2) examine whether gray and white matter structural integrity serve as possible mediators of the relationship between age and PFC function and functional connectivity, and (3) examine whether PFC function and functional connectivity serve as possible mediators of the relationship between age and cognitive performance. Important secondary analyses will examine similar questions regarding measures of chronicity of bipolar illness and illness course, such as duration since first episode, number of manic and depressive episodes, and cumulative exposure to psychotropic medications. PFC structural and functional deficits are recognized features of bipolar pathology and may be related to biological alterations in neurotrophic and cell signaling pathways. Some studies have found that structural deficits worsen with age among bipolar patients to a greater degree than expected in normal aging, but no study has yet combined measures of PFC gray matter size, white matter integrity and organization, resting perfusion, and functional brain response and connectivity in a single investigation of brain changes across the lifespan in bipolar disorder and healthy individuals. Our study is also designed to examine how age-associated brain measures relate to one another and to cognitive performance. We will use a cross-sectional design to study 85 patients with adolescent- or young-adult-onset Bipolar I disorder and 85 healthy individuals ranging in age from 30 to 79 years. Patients will be stably medicated, not experiencing a mood episode or significant mood or psychotic symptoms, and free of other Axis I disorders including current or recent substance abuse or dependence. Participants will be assessed for diagnosis and clinical history, current symptoms, cognitive performance, and brain structure and function as measured by magnetic resonance imaging. PFC gray matter thickness, white matter organization in tracts that connect with the PFC, resting perfusion and functional response of the prefrontal cortex and connected regions during working memory tasks will be measured. Results of this study will help characterize the course of brain pathology in bipolar disorder and enable future longitudinal investigations using the best measures and focusing on the most likely time period for change.
Little is known about how the brains of adults with bipolar disorder may change during aging and whether these changes are different from those seen in healthy aging. We will study the relationship of age to magnetic resonance imaging measures of prefrontal cortex gray matter thickness, white matter organization and integrity, and functional response during cognitive activities among groups of stable bipolar patients and healthy individuals. We will also examine how the brain measures relate to one another and to cognitive ability and examine how other chronicity measures may relate to age differences in the bipolar group. The results of this study will improve our knowledge about how aging influences brain abnormalities in bipolar disorder and may suggest new treatments designed to prevent negative effects and capitalize on any positive changes.
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