MedWire News: Cigarette smoking appears to exert a salutary effect on subjective, but not objective, measures of cognitive function in euthymic bipolar disorder patients, researchers report.
The findings echo those of a recent study reported by MedWire News showing that nicotine acts on acetylcholine receptors to mitigate symptoms of schizophrenia, and could explain why smoking is so widespread in both disorders.
Although smoking rates in the general population have been steadily declining during the past decade, there is no available evidence that rates are decreasing in psychiatric populations.
Part of the reason for this, say study author Roger McIntyre (University of Toronto, Ontario, Canada) and colleagues, could be that many patients feel smoking helps alleviate certain symptoms - in the case of bipolar disorder, memory impairments.
To investigate, they evaluated cognition in 43 subjects with bipolar disorder of whom 16 were current smokers and 27 were non-smokers.
Cognitive function was evaluated with a comprehensive battery of tests, which included measures of psychomotor speed, attention, memory, learning, and executive function.
There were no consistent differences in neuropsychological performance between current smokers and non-smokers on most tasks, the researchers report.
Notably though, the occurrence of subjective cognitive failures, as measured with the Cognitive Functioning Questionnaire, was lower for smokers compared with non-smokers.
However, in a logistic regression analysis lifetime “smoking load” was negatively associated with premorbid intelligence as estimated by the National Adult Reading Test.
McIntyre and colleagues say that their findings provide preliminary evidence that cigarette smoking may help cognition but call for further studies.
“An adequately powered study that precisely evaluates putative associations between smoking and cognitive function may possibly illuminate pathophysiological mechanisms and suggest novel therapeutic avenues for cognitive enhancement in bipolar disorder.”
The research is published in the journal Pharmacology Biochemistry and Behavior.