Dr Roger McIntyre answers a reader's question below. How would you answer? Take the quiz—for the answer and discussion, go to the next page
Answer: All of the above.
Bipolar disorder (BD) has been highly associated with disparate cognitive deficits, including attention, psychomotor performance, executive function, verbal fluency, learning, memory, and global neurocognitive functioning.1-4 The pertinacity of cognitive deficits in BD is underscored by reports that document an association between cognitive deficits and psychosocial functioning, workforce performance, and interpersonal adjustment.5-7
Emerging evidence also indicate that obesity is associated with reduced cognitive function in otherwise healthy individuals.8-15 The association between anthropometrics and cognitive deficits is detectable in individuals without obesity-associated comorbidities (eg, type 2 diabetes mellitus, hypertension) known to independently affect brain function.13,15.16 Most cognitive domains are reported to be adversely affected by excess weight with replicated abnormalities in measures of learning, memory, and executive function.9
It has been amply documented that individuals with BD are differentially associated with overweight/obesity and abdominal obesity and excess weight adversely effects illness presentation, course, and outcome. Available evidence is beginning to suggest that excess weight is negatively associated with cognitive function in BD.17
It is well established that impairments in executive function are apparent in mixed populations of individuals with BD as well as obese individuals without psychiatric disorders.3,4,9,12,13,18-22 It could be hypothesized that obesity and BD are associated with common CNS structural and/or functional changes in brain regions that subserve cognitive functioning. For example, frontal cortical regions that mediate executive function are hypometabolic in depressed individuals; similarly, overweight/obese individuals manifest reduced metabolic activity, as well as atrophy, in several cortical and subcortical structures.21,23,24
Moreover, the interrelationship between obesity and mood disorders may be due to a pathophysiological nexus that includes abnormalities in hypothalamus-pituitary-adrenal axis function, inflammatory and metabolic systems, disruption of brain circuitry, all of which are potential mediators of cognitive function.9,20,25,26 Further structural and functional investigations, as well as the establishment of mechanisms that mediate cognitive deficits in obesity and BD, are required before a firm conclusion can be drawn.
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2. Malhi GS, Ivanovski B, Hadzi-Pavlovic D. Neuropsychological deficits and functional impairment in bipolar depression, hypomania and euthymia. Bipolar Disord. 2007;9:114-125.
3. Martinez-Aran A, Vieta E, Colom F, et al. Cognitive dysfunctions in bipolar disorder: evidence of neuropsychological disturbances. Psychother Psychosom. 2000;69:2-18.
4. Martinez-Aran A, Vieta E, Reinares M, et al. Cognitive function across manic or hypomanic, depressed, and euthymic states in bipolar disorder. Am J Psychiatry. 2004;161:262-270.
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17. Yim CY, Soczynska JK, Kennedy SH, Woldeyohannes HO, Brietzke E, McIntyre RS. The effect of overweight/obesity on cognitive function in euthymic individuals with bipolar disorder. Eur Psychiatry. 2011 May 11 (Epub ahead of print].
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19. Jamrozinski K. Do euthymic bipolar patients have normal cognitive functioning? Curr Opin Psychiatry. 2010;23:255-260.
20. Martinez-Aran A, Vieta E, Colom F, et al. Cognitive impairment in euthymic bipolar patients: implications for clinical and functional outcome. Bipolar Disord. 2004;6:224-232.
21. Robinson LJ, Thompson JM, Gallagher P, et al. A meta-analysis of cognitive deficits in euthymic patients with bipolar disorder. J Affect Disord. 2006;93:105-115.
22. Walther K, Birdsill AC, Glisky EL, Ryan L. Structural brain differences and cognitive functioning related to body mass index in older females. Hum Brain Mapp. 2010;31:1052-1064.
23. Drevets WC, Price JL, Furey ML. Brain structural and functional abnormalities in mood disorders: implications for neurocircuitry models of depression. Brain Struct Funct. 2008;213:93-118.
24. Volkow ND, Wang GJ, Telang F, et al. Inverse association between BMI and prefrontal metabolic activity in healthy adults. Obesity (Silver Spring). 2009;17:60-65.
25. Capuron L, Miller AH. Cytokines and psychopathology: lessons from interferon-alpha. Biol Psychiatry. 2004;56:819-824.
26. Thompson JM, Gallagher P, Hughes JH, et al. Neurocognitive impairment in euthymic patients with bipolar affective disorder. Br J Psychiatry. 2005;186:32-40.