The association between polypharmacy and late life deficits in cognitive, physical and emotional capability: a cohort study

Abstract

Background Polypharmacy is a growing health concern for older adults and is associated with poorer clinical outcome. Objective This study aim is to investigate the association between polypharmacy and impairment in cognitive, physical and emotional capability controlling for the confounding effect of co-morbidities. Setting The Aberdeen 1936 Birth Cohort from 1999 to 2004. Method Recruited were 498 dementia free participants around 64 years old and recruited into wave one. Linear regression and structural equation models were used. Models were adjusted for the effect of age, gender, childhood IQ, education and Body Mass Index. A triad of impairment was defined as a composite measure of impairment in cognitive, physical and emotional function. Main outcome measure The relationships between polypharmacy, co-morbidity and triad of impairment. Results The prevalence of polypharmacy was 12.3% in this relatively healthy sample. Polypharmacy was significantly associated with increased impairment in cognitive, physical and emotional ability (β = 3.6, p = 0.003) after controlling for the effect of comorbidities and other confounding variables. As expected, higher childhood IQ and educational achievement had protective effects against impairment while higher comorbidity score and Body Mass Index were associated with increased impairment in this population. Conclusions The independent association of polypharmacy and reduced cognitive, physical and emotional capability makes this a promising target for predicting and potentially reducing the risk of impairment and associated healthcare costs in older adults. Longitudinal studies are required to investigate the underlying mechanisms for the observed relationships further.

Keywords: Cognitive impairment; Emotional impairment; Observational cohort study; Older adults; Physical impairment; Polypharmacy; United Kingdom.

Fig. 1

Path diagram of hypothesised model (n = 341). Solid lines represent hypothesised path and dash line represent path added to the model based on the modification indices. ef emotional impairment factor, pf physical impairment factor, gf cognitive ability factor. All the standardised regression weights represents in the diagram are statistically significant (p < 0.001). r1 to r5 are residual (error) terms within the model