Associations Between Medication Use and Mental Health in Older Women: A Cross-Sectional Analysis of 5,502 Women Aged 76 to 81.

Abstract

To the Editor: The association between use of medications in older people and poor mental health has been investigated in a limited number of studies, and results have been contradictory.1, 2 Given possible associations between medications and mental health,3, 4 there is potential for multiple medication use to contribute to age-associated declines in mental health,5 but the evidence concerning the association between mental health and medication use is scarce. The aim of this study was to examine the association between medication use and mental health in older women (aged 76–81) from the Australian Longitudinal Study on Women Health (ALSWH).6 This study involved women from the 1921–26 birth cohort of the ALWSH who participated in the third longitudinal survey (2002) and provided consent for linkage to data on government-subsidized medications in the Pharmaceutical Benefits Scheme (PBS) database, for the period of April 1 to June 30, 2002. Total medication use was defined as the number of different medications using full Anatomical Therapeutic Chemical (ATC) codes (chemical substance group) and therapeutic main groups, defined as the total number of different classes of medications. These two measures of medications were grouped into ordinal categories. Mental health was measured using the Medical Outcomes Study 36-item Short-Form Health Survey (SF-36) mental health score reported on the 2002 survey.7 Linear regression analysis was performed to investigate the associations between number and classes of medications and mental health scores. Of the 12,432 women recruited for ALSWH in 1996 (aged 70–75), 8,646 (69.5%) completed Survey 3 in 2002 (aged 76–81), with 5,502 (63.6%) providing consent for PBS linkage. Of the 5,502 women included in this study, 4,884 (88.7%) had a claim for at least one medication in the PBS data; 32.2% had claims for one to three medications, 31.7% for four to six, 16.1% for seven to nine, and 8.7% for 10 or more. Table 1 presents associations between the SF-36 mental health score and medication use after adjustment for other factors. The final model includes all statistically significant explanatory factors (all P ≤ .05). Older women who used one to three medications had higher mental health scores (better mental health) than those who did not use any (beta coefficient (β) = 1.53, 95% confidence interval (CI) = 0.02 ̶3.09, P = .05). After controlling for other significant factors, women who used 10 or more medications had lower mental health scores (poorer mental health) (β = −2.89, 95% CI = −5.05 to −0.73, P = .009) than those who did not use any. Analyses were repeated for each main therapeutic group (using unique reporting of second-level ATC codes), with similar results to overall medication use (data not shown). To the knowledge of the authors, this study is one of few to specifically examine the association between overall medication use and mental health in older women. The findings support the hypothesis that the use of more medications is associated with poorer mental health in older women. Nevertheless, although multiple medications may have adverse effects, therapeutic benefits may outweigh these effects, especially when women have significant morbidity. Health professionals should ask about mental health when undertaking medication review. The ALSWH represents a large cohort of older Australian women who are broadly representative of women in this age group in the Australian population.8 Information on medications was obtained using PBS data, which does not include all medicines used, such as over-the-counter medications and medications outside the PBS frame.9 However, because many older people in this cohort receive government concessions, it is likely that the effect of this data omission was minimal. Because this was a cross-sectional study, the analysis does not allow temporal associations or causality to be investigated. Further analysis of longitudinal data will allow temporal associations to be examined. Older women who use a small number of medications (1–3) have better mental health, whereas use of 10 or more medications is associated with poorer mental health. The findings underscore risk of poor mental health in older women using multiple medications. This research was supported by the Saudi Ministry of High Education (The King Abdullah bin Abdul-Aziz Scholarship Program). The research on which this paper is based was conducted as part of the Australian Longitudinal Study on Women's Health by the University of Newcastle and the University of Queensland. We are grateful to the Australian Department of Health for funding and to the women who provided the survey data. This research was supported by infrastructure and staff of the Research Centre for Gender, Health and Ageing, who are members of the Hunter Medical Research Institute. Author Contributions: Alsalami, Forder, Byles: study design, data analysis, data interpretation, manuscript preparation. Milton, McEvoy: data interpretation, manuscript preparation. Sponsor's Role: The sponsor did not have a role in the design, method, data collection, analysis, or preparation of the article.