Poor pulmonary function implicated in dementia

Poor pulmonary function, particularly in midlife, may contribute to an increased risk of later dementia, as suggested in the results of a meta-analysis.

Researchers searched multiple online databases for studies linking pulmonary function or respiratory illness to incident dementia using the following keywords: dementia, Alzheimer, forced expiratory volume (FEV), forced vital capacity (FVC), peak expiratory flow (PEF), asthma, COPD, respiratory disease, lung disease and pneumonia, among others.

The search yielded 20 studies for inclusion in the meta-analysis: 10 studies reported pulmonary function and 11 did respiratory illness (one study reported both pulmonary function and respiratory illness).

Pooled data revealed the lowest vs highest quartile of FEV in one second (FEV1) conferred a 1.4-fold greater dementia risk (hazard ratio [HR], 1.46, 95 percent confidence interval [CI], 0.77–2.75; p=0.092; I², 69.3 percent; n=62,209; two studies).

Furthermore, every 1-standard deviation decrease in FEV1 was associated with a 28-percent risk increase (HR, 1.28, 95 percent CI, 1.03–1.60; p=0.028; I², 78.2 percent; n=67,505; six studies).

Respiratory illness also showed a similar magnitude of association with dementia risk (HR, 1.54, 95 percent CI, 1.30–1.81; p<0.001; I², 92.4 percent; n=288,641; 11 studies). These associations were observed across different countries and research groups, in both men and women, and persisted despite adjustments for a range of confounding factors.

The researchers underscored a need for further investigation to establish whether or not the association between pulmonary function and cognition might reflect a cause-and-effect relation.