Smoking may impair cognitive performance
Smoking appears to result in poorer cognitive performance in patients, their siblings and healthy controls compared with nonsmoking, a recent study has shown. This suggests that smoking cessation may improve processing speed in patients.
Of the patients, 66.6 percent smoked at baseline compared with 38.3 percent of the siblings and 25.2 percent of the control participants. There were significant multicross-sectional associations between smoking and lower processing speed in the patients and control groups vs the nonsmoking patient group (estimate, –2.38; SE, 0.84) and the nonsmoking control group (estimate, –3.13; SE, 1.06).
Smoking was also significantly associated with lower performance in working memory and reasoning and problem solving among siblings compared with nonsmoking. In addition, the number of cigarettes smoked per day negatively correlated with these domains.
Furthermore, patients, but not siblings and control participants, who quit smoking had a significant improvement in processing speed (estimate, 4.90; SE, 1.73).
This cohort study included patients with nonaffective psychosis (n=1,094), their siblings (n=1,047) and healthy controls (n=579). The authors analysed smoking and cognitive functioning using the Composite International Diagnostic Interview and a test battery, respectively, as baseline and at 3- and 6-year follow-ups.
Associations between smoking and cognitive domains were evaluated using multivariate linear mixed-effects regression analyses while adjusting for variation in demographic factors, psychopathology, medication and substance use. The authors also applied Bonferroni correction for multiple testing.
“The high prevalence of smoking and cognitive deficits in schizophrenia patients is well known, but findings regarding the association between the two are contradictory, and longitudinal studies are lacking,” the authors said.