Cell-based serum anticholinergic activity assay and working memory in cognitively healthy older adults before and after scopolamine: An exploratory study

Abstract

Background: A new cell-based serum anticholinergic activity (cSAA) assay that measures anticholinergic activity specifically at muscarinic M1 receptors and eliminates many of the drawbacks of the existing assay was developed by our team. Aims: We aimed to study the relationship between changes in working memory and executive function with changes in cSAA using the new assay in cognitively healthy older adults. Methods: Cognitively healthy participants aged 50 years and above, received a single dose of 0.4 mg of intravenous scopolamine. Cognition and cSAA levels were measured before and 30 min after receiving scopolamine. Cognition was measured using the Cambridge Neuropsychological Test Automated Battery. Results: Ten participants were recruited, and nine (mean age = 69.8, SD = 9.5, range 59–86 years) completed the study. Following scopolamine, participants experienced an increase in cSAA (cSAA pre = 0.90 ± 0.97 vs cSAA post = 12.0 ± 3.70 pmol/L; t-test ( df = (8) = −9.5, p < 0.001). In addition, there was an association between change in cSAA and changes in working memory (Spearman’s ρ = 0.68, p = 0.042) and executive function (Spearman’s ρ = 0.72, p = 0.027). Conclusions: In our sample of cognitively healthy older adults, the new cSAA assay was able to quantify the scopolamine induced increase in anticholinergic load which correlated significantly with the observed decline in working memory and executive function.