Seasonal cognitive variation found in bipolar disorder families
MedWire News: Patients with bipolar disorder and their first-degree relatives show seasonal variations in mood that negatively influence neuropsychological test performance, research shows.
Mentally healthy controls without a family history of mood disorders showed no such seasonal variation, suggesting a genetic component to cognition.
Studies show that neuropsychological impairments in bipolar disorder are not restricted to mood episodes but may also be present in euthymic individuals and include executive functioning, verbal memory, attention, and processing speed deficits.
Meanwhile, there is evidence of seasonal variation in mood and behavior as well as abnormalities in circadian preference in bipolar disorder.
Elina Rajajärvi (National Institute for Health and Welfare, Helsinki, Finland) and colleagues administered a structured diagnostic interview and neuropsychological test battery to 32 familial bipolar I disorder patients, 40 of their unaffected first-degree relatives, and 50 mentally healthy controls, all from population-based samples.
Bipolar disorder patients and their relatives filled in the Seasonal Pattern Assessment Questionnaire (SPAQ) and the Horne–Östberg Morningness– Eveningness Questionnaire (MEQ).
Among bipolar disorder patients and their relatives, those who reported seasonal variations in mood and behavior scored worse on the measures of visuoconstructional function, visuospatial reasoning, auditory attention and working memory, and verbal memory than those with no seasonal variation.
The season when a neuropsychological test battery was administered was associated with test performance. Patients and relatives tested in spring, summer, or fall performed better than in winter in measures of visual and verbal attention and working memory, verbal ability, verbal fluency and executive functioning.
By contrast, there was no association between season and test scores among the mentally healthy controls
“In studying cognitive endophenotypes of bipolar disorder it may be warranted to take the seasonal variation of the test performance and the possible seasonal variation in mood and behavior into account when the neuropsychological examination is done,” Rajajärvi et al conclude in the Journal of Affective Disorders.
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By Andrew Czyzewski