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Cognitive Decline and Polypharmacy in an Elderly Population

2015; Wiley; Volume: 63; Issue: 2 Linguagem: Inglês

10.1111/jgs.13283

1532-5415

Ximena Oyarzún‐González, Kira C. Taylor, Steven R. Myers, Susan B. Muldoon, Richard Baumgartner,

Intensive Care Unit Cognitive Disorders

To the Editor: The Department of Health and Human Services estimates that, by 2030, there will be 72.1 million individuals aged 65 and older in the United States.1 The prevalence of mild cognitive impairment (MCI) in the elderly population is between 3% and 19%, with an incidence of 8 to 58 per 1,000 per year and a risk of developing dementia of 11% to 33% over 2 years.2 The higher prevalence of chronic diseases makes this population more likely to be taking multiple medications. Polypharmacy, defined most commonly as the concomitant use of five or more medications, is a poorly studied factor in relation to MCI, but may play an important role.3 A follow-up study in a Finnish population of 294 elderly people between 2004 and 2007 recorded the use of medications and the cognitive function of participants.3 The authors observed that excessive polypharmacy, defined as the concomitant use of 10 or more medications, was associated with less cognitive capacity measured using the Mini-Mental State Examination (MMSE) than in a non-polypharmacy group. Considering the dearth of scientific studies analyzing the effects of polypharmacy on cognitive decline, particularly in the U.S. population, the current study examined data from the New Mexico Aging Process Study (NMAPS) to further investigate the effects of polypharmacy on cognitive status changes. A longitudinal cohort study was developed using the data from 572 participants from NMAPS to measure the effect of polypharmacy on MMSE scores and risk of MCI. Multivariable mixed linear regression models and generalized estimating equations were used to estimate these associations, adjusting for sex, age at baseline, Charlson Comorbidity Index (CCI), presence of the apolipoprotein (Apo)E ε4 allele, body mass index (BMI), and hypertension. Most of the study subjects were female (63.6%), white (88.5%), and married (66.6%); 47.2% had 12 to 16 years of education, and 36.2% had more than 16 years of education. Polypharmacy was associated with a 0.11 ± 0.09-point lower MMSE score (P = .23) and a greater risk of MCI (odds ratio = 1.95, 95% confidence interval = 0.40–9.43) (Table 1). Thus, even though the sample size was small, and the associations were not statistically significant, the results suggest that polypharmacy could be an important factor in cognitive decline. Other notable findings included the detrimental effects of male sex, CCI greater than 0, and the ApoE ε4 allele on cognitive decline, although only the CCI was statistically significant. Furthermore, hypertension (treated) was significantly associated with higher MMSE scores. These results were consistent with the analyses done for MCI and for change in MMSE scores over time. The sampled population was unusually healthy and educated compared with the general U.S. population. The prevalence of diabetes mellitus (0.53%), hypertension (34.5%), and obesity (10.5%) in the studied sample were much lower than the prevalences of 26.9%, 71.6%, and 35.0%, respectively, described for those diseases in Americans aged 65 and older.4, 5 According to the U.S. Department of Health and Human Services, the percentage of older people who completed high school rose from 28% to 71% between 1970 and 2003.6 Approximately 83% of the sample studied had completed a high school education, and taking into consideration that the recruitment process was between 1979 and 2003, it is possible to establish that this sample was unusually highly educated. These characteristics may limit the generalizability of these results to the U.S. population. Anticholinergic drugs and other drugs categorized as potentially inappropriate medications (PIMs) have been found to be strongly associated with cognitive impairment, whereas other categories of drugs have not shown an association.7 In addition, the more drugs an individuals is taking, the more likely he or she is to observe an adverse drug event, such as cognitive impairment.8-10 It was not possible to examine specific drug types or PIM use in this study, which are possible underlying mechanisms for this association, but it will be important that future research takes into consideration that specific drugs can have a negative or positive effect on cognitive performance, or no effect at all, which makes it even more important to incorporate the specific types of drugs in future research. Nevertheless, the results obtained suggest that it is important for health professionals to evaluate medication use in elderly adults thoroughly and try to limit the number of medications (prescription and over the counter), not only to avoid possible adverse drug reactions and interactions, but also to achieve good treatment adherence. The authors appreciate the work, time, and effort from participants and research staff associated with the NMAPS, as well as the funding received to develop it. Conflict of Interest: The editor in chief has reviewed the conflict of interest checklist provided by the authors and has determined that the authors have no financial or any other kind of personal conflicts with this paper. The data analyzed for this paper were collected under Grants R01 AG10149 and R01 AG 02049 from the National Institutes of Health. Author Contributions: Oyarzun-Gonzalez: study objectives, data cleaning and analysis, interpretation of results, drafting the manuscript. Taylor: data analysis, interpretation of results, drafting the manuscript. Muldoon: data analysis, interpretation of data, manuscript preparation. Myers: interpretation of results, manuscript preparation. Baumgartner: principle investigator of study in which data analyzed were collected, manuscript preparation. Sponsor's Role: The sponsors of NMAPS had no role in the study design, methods, analysis, or preparation of the manuscript.