Long-Term Use of Medications with Anticholinergic Activity in Older Adults with Intellectual Disability: Prescribing Challenges and Impact on Health Outcomes

Abstract

Background: Older adults with intellectual disability are exposed to polypharmacy and a high anticholinergic burden due to the high prevalence of mental and neurological disorders. A cumulative anticholinergic burden has been associated with adverse effects such as daytime drowsiness, constipation, and poorer performance in activities of daily living, according to cross-sectional studies. Additionally, long-term exposure to anticholinergic burden has been associated with adverse effects in older adults in the general population, including cognitive decline, physical function deterioration, higher mortality rates, chronic constipation, increased risk of falls, and a higher likelihood of developing dementia or Alzheimer's disease. However, based on preliminary research, no studies have specifically examined the adverse effects of long-term exposure to medications with anticholinergic activity in older adults with intellectual disability. Objectives: This thesis aimed to evaluate the factors associated with the use of medication with anticholinergic activity in older adults with intellectual disability by addressing the following key objectives: i) map and examine existing research on adverse effects of long-term use of medications with anticholinergic activity in this population (evidence gathering stage), ii) assess anticholinergic exposure at two timepoints over a ten-year period and investigate the associated outcomes (evidence gathering stage), iii) explore prescribers' perspectives on prescribing and deprescribing of medications with anticholinergic activity, identifying barriers and facilitators to deprescribing (theoretical development), and iv) data synthesis to assess the development of an intervention aimed at enhancing the prescribing and deprescribing of medications with anticholinergic activity among older adults with intellectual disability, based on both the theoretical foundation and the gathered evidence. Methods: The Medical Research Council framework on complex interventions was used to provide the theoretical foundation for the design of an intervention aimed at optimising anticholinergic prescribing for older adults with intellectual disability. A scoping review was conducted to evaluate existing studies of the adverse effects of long-term anticholinergic burden in the population. A longitudinal cohort study using Data from Wave 1 and Wave 4 from the Intellectual Disability Supplement to the Irish Longitudinal Study on Ageing, which are ten years apart, was used to assess the Anticholinergic Cognitive Burden (ACB), with ACB scores calculated for the same cohort at both timepoints. Multinomial logistic regression was used to analyse the factors associated with high ACB scores at Wave 4, while logistic regression was used to examine outcomes at Wave 4 associated with mild and high ACB at Wave 1. Semi-structured interviews were also conducted with healthcare professionals who prescribe medication for older adults with intellectual disability in Ireland. The Theoretical Domains Framework was applied to identify barriers and facilitators to the deprescribing of medications with anticholinergic activity from the prescribers' perspectives. Results: The scoping review found no studies examined adverse effects associated with long-term anticholinergic activity exposure among older adults with intellectual disability. The longitudinal study found that approximately 70% of participants reported use of medications with anticholinergic activity at both timepoints, with no significant change in ACB scores between the two waves. Antipsychotics were the most common contributors to anticholinergic exposure, followed by anticholinergics, antiepileptics, and antidepressants at both timepoints. Mild and high ACB scores at Wave 1 were significantly associated with an increased risk of falls and mental health conditions after 10 years. The qualitative study identified several facilitators of deprescribing in different domains: environmental context and resources of medical records; prescriber Knowledge and Skills (knowledge of appropriate prescribing and deprescribing skills); social influences (carer/family involvement) and beliefs about consequences (positive impacts of deprescribing and use of non-pharmacological treatments). Identified barriers to deprescribe medications with anticholinergic activity included environmental context and resources; Knowledge and social influences. Conclusion: Older adults with intellectual disability are exposed to a high anticholinergic burden and more likely for a sustained period of time, and this was significantly associated with a higher risk of falls and mental health conditions. The prescribing and deprescribing of medications with anticholinergic activity for older adults with intellectual disability is a complex process that requires an intervention to support prescribers in making informed decisions.