Smoking and cognitive function in Parkinson's disease

Authors

  • Marc G. Weisskopf PhD,

    Corresponding author
    1. Department of Environmental Health, Harvard School of Public Health, Boston, Massachusetts, USA
    • Department of Environmental Health, Harvard School of Public Health, Landmark Center, 3rd floor East, PO Box 15697, Boston, MA 02215
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  • Francine Grodstein ScD,

    1. Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
    2. The Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
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  • Alberto Ascherio MD

    1. Department of Epidemiology, Harvard School of Public Health, Boston, Massachusetts, USA
    2. The Channing Laboratory, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts, USA
    3. Department of Nutrition, Harvard School of Public Health, Boston, Massachusetts, USA
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Abstract

The risk of dementia among Parkinson's disease (PD) patients is greatly elevated compared to controls, yet little is known about determinants of cognitive function among PD patients. We assessed the relation between cigarette smoking prior to disease onset and later cognitive function among PD patients (n = 286) and age- and sex-matched controls (n = 1144) participating in the Nurses' Health Study and Health Professionals Follow-up Study. Both groups completed telephone-administered assessments of cognitive function. We used linear regression to calculate mean differences in cognitive test scores across smoking categories, adjusted for age, education, sex, age at onset of PD, and years since diagnosis. PD patients scored significantly worse on all tests than their matched controls. In analyses only among PD cases, but not among controls, current smokers at PD onset scored worse than never smokers on the Telephone Interview for Cognitive Status (difference = −0.82, 95% CI: −1.33, −0.30, P = 0.002) as well as on a global score combining results of all tests (difference = −0.36, 95% CI: −0.72, 0.01, P = 0.06). This difference was equivalent to the difference in global score observed among controls ∼10 years apart in age. Analyses of pack-years of smoking prior to disease onset gave similar results. These findings, nested in prospective cohort studies, suggest that cigarette smoking prior to disease onset is associated with worse cognitive function in PD. © 2007 Movement Disorder Society

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