Ten-Year Outcomes of Anticholinergic Use Among Older Adults With Intellectual Disability: Findings From the Intellectual Disability Supplement to the Irish Longitudinal Study on Ageing (IDS-TILDA).

Background: People with intellectual disability are frequently exposed to medication with anticholinergic activity. In the general population, the long-term exposure to anticholinergics has been associated with declines in both physical and cognitive function. This study aimed to examine anticholinergic exposure longitudinally in a cohort of older adults with intellectual disability (aged 40 years or over).

Method: The study examined individuals with intellectual disability aged 40 and over, who participated at two time points (Waves 1 and 4), 10 years apart, in the Intellectual Disability Supplement to the Irish Longitudinal Study on Ageing (IDS-TILDA). The Anticholinergic Cognitive Burden (ACB) scale was used to quantify anticholinergic exposure. Logistic regression analysis was employed to examine the adverse outcomes reported at time point 2 in relation to ACB scores at time point 1. Models were adjusted for age, gender, level of intellectual disability, residence, epilepsy and polypharmacy.

Results: The study included 487 participants who provided medication data at both time points. Anticholinergic exposure remained consistent over the studied period, with approximately 30% having no exposure, 40% having mild exposure (ACB = 1-4) and 30% having high exposure (ACB = 5+). Antipsychotic medications contributed the most to the total score at both time points (Wave 1 = 35%, Wave 4 = 37%), with other anticholinergics, antiepileptics and antidepressant medications contributing 10%-16% each. Mild and high ACB scores at time point 1 were significantly associated with a higher risk of falls (odds ratio [OR] = 1.86, 95% CI: 1.03-3.38) and mental health conditions (ACB 1-4; OR = 6.60, 95% CI: 3.69-11.77; ACB 5+, OR = 17.38, 95% CI: 8.97-33.61) and lower OR for reporting dementia/Alzheimer's disease (ACB 1-4; OR = 0.39, 95% CI: 0.15-0.97; ACB 5+; OR = 0.21, 95% CI: 0.07-0.64).

Conclusion: Older adults with intellectual disability are exposed to high anticholinergic burden at the two time points, 10 years apart. Being exposed to anticholinergics at Wave 1 is significantly associated with a higher risk of falls and reporting mental health conditions at Wave 4. A review of antipsychotic prescribing practice is urgently needed to reduce the anticholinergic exposure and its adverse outcomes among older adults with intellectual disability.