Ventilatory capacity and risk for dementia

Previous studies have found a relationship between single indicators of ventilatory capacity and measures of cognitive function, but have not addressed dementia specifically. This study examined the relationship between different indicators of ventilatory capacity and dementia, diagnosed according to the Diagnostic and Statistical Manual of Mental Disorders, Revised Third Edition, controlling for important confounding factors.

Cross-sectional data on participants (n = 437) of the Berlin Aging Study (BASE), which are representative of former West Berlin's living population aged 70 years and older, were analyzed. Ventilatory capacity was measured by spirometry as peak expiratory flow rate (PEF-R), forced expiratory volume in 1 second (FEV-1), maximal expiratory flow at 50% of forced vital capacity (MEF50%FVC), and maximal expiratory flow at 25% of forced vital capacity (MEF25%FVC). Odds ratios (OR) for dementia associated with ventilatory capacity were obtained by logistic regression, adjusting for age, gender, education, ApoE4 status, chronic obstructive pulmonary disease, smoking, heart failure, visual and auditory functioning, grip strength, and former physical activity.

Separate analyses for PEF-R, FEV-1, MEF50%FVC, and MEF25%FVC revealed significantly increased odds for dementia among subjects in the lowest compared with the best functioning group in ventilatory testing. The OR associated with PEF-R > or = 2 l/s was found to be 20.4 (confidence interval [CI] 5.1-82.7). For FEV-1, MEF50%FVC, and MEF25%FVC ORs of 7.5 (CI 2.1-27.9), 4.3 (CI 1.5-12.5), and 4.7 (CI 1.3-17) were obtained, respectively.

Ventilatory capacity, measured by spirometry in a representative sample of very elderly people, is cross-sectionally related to dementia. Taking evidence from longitudinal studies into account, this result suggests that decreased respiratory function may increase the risk for dementia, independent from already known risk factors.