Risk of anticholinergic burden in adults with intellectual disabilities: a Scottish retrospective cohort study of...

Several drugs have anticholinergic side effects that are associated with adverse health outcomes. Anticholinergic burden studies in adults with intellectual disabilities (ID) have focused exclusively on older adults. This study investigates anticholinergic burden and its associations in adults with ID of all ages (17-94 years).

Adults with ID (n = 4 305), each with three general population age-sex-neighbourhood-matched controls (n = 12 915), were linked to their prescribed medications with anticholinergic effects between 2009 and 2017. Analyses were undertaken using logistic regression models.

Adults with ID were more likely to be prescribed any anticholinergic medicines, odds ratio (OR) = 1.49 (1.38-1.59), especially 'very strong' risk medicines, OR = 2.59 (2.39-2.81); 48.5% had very high total anticholinergic burden (3+) compared with 35.4% of the general population, OR = 1.77 (1.64-1.90). This group difference was greater for males, OR = 2.02 (1.84-2.22), than females, OR = 1.48 (1.33-1.65). Adults with ID had significantly higher odds of having very high total anticholinergic burden up to 75 years old, with the greatest group effect occurring in younger ages, 17-24-year-olds, OR = 3.05 (2.39-3.89), and the extent of the difference decreased as age increased. The main effect of neighbourhood deprivation showed greater group differences with increasing affluence of neighbourhood. Results examining only the ID group showed that very high total anticholinergic burden was greatest for females, OR = 1.21 (1.07-1.37), and those over age 55, and extent of neighbourhood deprivation was not significant.

Adults with ID are at higher risk of anticholinergic burden than the general population, especially young adults. Overall anticholinergic burden increased with age, but burden was high across all ages in the ID group. Very high total anticholinergic burden is prevalent across all types of neighbourhoods for the adults with ID, in contrast to the steeper gradient seen in the general population. Adults with ID have increased likelihood of unintended adverse effects, regardless of potential confounds, so clinicians undertaking medication reviews need to consider anticholinergic side effects and cumulative burden across concomitant medications, including in young adults with ID, not just older adults, and particularly women.