Relationships Between a New Cultured Cell-Based Serum Anticholinergic Activity Assay and Anticholinergic Burden Scales or Cognitive Performance in Older Adults

Relationship of the revised anticholinergic drug scale with cultured cell-based serum anticholinergic activity and cognitive measures in older adults with mild cognitive impairment or remitted depression

OBJECTIVE

The Anticholinergic Drug Scale (ADS) is a commonly used measure of anticholinergic exposure. This study describes an expanded and revised version of the ADS (rADS) and its relationship with cultured cell-based serum anticholinergic activity (cSAA) and cognitive measures.

STUDY PARTICIPANTS

Adults aged 60 years and older with mild cognitive impairment (MCI), remitted major depressive disorder (rMDD), or both, participate in the Prevention of Alzheimer's Dementia with Cognitive Remediation plus Transcranial Direct Current Stimulation (PACt-MD) study.

STUDY DESIGN

Cross-sectional investigation of data from the PACt-MD study.

MEASURES

The rADS includes ratings for 1047 distinct products, about twice as many as the originally published scale; previously published ratings were revised for 40 drugs. Total rADS scores were calculated as sums of ratings of all drugs taken by participants; cSAA was measured in the participants' sera; cognitive performance included measures of executive function, language, processing speed, verbal memory, visuospatial memory, working memory, and an overall composite score.

STATISTICAL ANALYSIS

The relationship between rADS total scores and cSAA was examined using a Spearman rank correlation coefficient. Relationships between rADS total scores and cognitive performance measures were explored in multivariable linear regression models.

RESULTS

The sample included 310 participants (mean [standard deviation] age: 72 (6) years; 61.6% were women, and 81.6% had MCI [with or without rMDD]). Total rADS scores were positively correlated with cSAA (Spearman's correlation coefficient: 0.178, p = 0.0016). Total rADS scores were not significantly associated with cognitive performance.

CONCLUSIONS

The revised scale is recommended as a replacement for the original ADS since it includes ratings for more drugs and was significantly, albeit weakly, associated with cSAA, similar to previous findings using the original ADS.

Impact of Anticholinergic Burden and Clinical-Demographic Characteristics on Incident Dementia in Parkinson Disease

PURPOSE

Anticholinergic medication use measured via the Anticholinergic Cognitive Burden (ACB) scale has been associated with an increased dementia incidence in older adults but has not been explored specifically for Parkinson disease dementia (PDD). We used adjusted Cox models to estimate the risk of incident PDD associated with demographic factors, clinical characteristics, and time-varying total ACB in a longitudinal, deeply-phenotyped prospective PD cohort.

MAJOR FINDINGS

56.5% of study participants were taking ACB-scale drugs at enrollment. Increasing age, motor symptom burden and psychosis were associated with PDD risk. Female sex and educational achievement were protective against PDD. ACB categories were not associated with PDD overall, but depression and impulse control disorder were strongly associated with PDD in a subsample with high baseline ACB.

CONCLUSIONS

Patient and clinical factors modify PDD risk. PD drug safety and drug-disease interaction studies may require considering multiple mechanisms and including dose-based, prospectively acquired medication exposure measures.

Considering medication exposure in genomic association studies of cognition in psychotic disorders

Cognitive dysfunction is a core feature of psychosis-spectrum illnesses, and the characterization of related genetic mechanisms may provide insights regarding the disease pathophysiology. Substantial efforts have been made to determine the genetic component of cognitive symptoms, without clear success. Illness-related moderators and environmental factors such as medications hinder the detection of genomic association with cognition. Polypharmacy is common in psychotic disorders, and the cumulative effects of medication regimens can confound gene-cognition associations. A review of the relative contributions of important pharmacological and genetic relationships identifies that the effects of medications on cognition in psychotic disorders may be at least, if not more, impactful than individual genes, thus underscoring the importance of accounting for medication exposure in gene-cognition association studies.

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

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.

A calcium fluorescence assay for quantification of cholinergic receptor activity of clinical drugs in serum - comparison with radioactive methods

A new approach is described for quantifying cholinergic receptor activation status human blood samples, based on M1 receptor-driven mobilization of intracellular calcium stores. The assay identifies anticholinergic as well as agonist cholinergic receptor activity. As a cell-based procedure, the assay shares the high efficiency of recently developed M1 receptor binding protocols, but differs from the latter in relying on fluorescence rather than radioactivity measurements. The assay targets a true functional effect insofar as it reflects a time-dependent process of net changes in activation of cholinergic receptors. Results from experiments with M1-expressing CHO cells exposed to a fluorogenic dye and the standard cholinergic agonist carbachol revealed the assay's ability to isolate pure agonist effects of clinical compounds as well as the net effects of serum containing agonist and antagonist factors. The new protocol thus provides two additional quantitative indices of cholinergic receptor activity in human serum, namely pure agonistic effects and net agonist/antagonist effects. As such, it could constitute a very useful addition to efforts to quantify global cholinergic status in human serum in various clinical conditions. By relying on fluorescence measures it should also prove much more accessible than radioactivity-based protocols.