Serum anticholinergic activity in a community-based sample of older adults: relationship with cognitive performance

Serum anticholinergic activity (SAA), as measured by a radioreceptor assay, quantifies a person's overall anticholinergic burden caused by all drugs and their metabolites. In several small geriatric patient groups, SAA has been associated with cognitive impairment or frank delirium. To our knowledge, there has not yet been any systematic study of the prevalence of SAA and its effect on cognition in a community-based population.

Serum anticholinergic activity was measured in 201 subjects who were randomly selected among the participants in an epidemiological community study, based on their age and sex. Cognitive performance was assessed with use of the Mini-Mental State Examination. The association between SAA and cognitive performance was examined using a univariate analysis and a multiple logistic regression model, adjusting for age, sex, educational level, and number of medications.

Serum anticholinergic activity was detectable in 180 (89.6%) participants (range, 0.50-5.70 pmol/mL). Univariate testing showed a significant association between SAA and Mini-Mental State Examination scores. Logistic regression analysis indicated that subjects with SAA at or above the sample's 90th percentile (ie, SAA >/=2.80 pmol/mL) were 13 times (odds ratio, 1.08-152.39) more likely than subjects with undetectable SAA to have a Mini-Mental State Examination score of 24 (the sample's 10th percentile) or below.

To our knowledge, this is the largest analysis of SAA and the first to examine its extent and relationship with cognitive performance in a community sample. Its results suggest that SAA can be detected in most older persons in the community and confirm that even low SAA is associated with cognitive impairment.