Helmes, Edward, and Ostbye, T. (2011) Cognitive associations of benzodiazepine use in older adults. International Psychogeriatrics, 23 (Supplement 1). PS02.103. S344-S345.

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Abstract

Use of prescription medications for various conditions is highly prevalent in older adults, often leading to the use of multiple medications. The resulting polypharmacy is widely recognized as a risk factor for many negative outcomes, but less is known about the risks of specific types of medication upon cognitive functions. Benzodiazepines are commonly prescribed for the treatment of anxiety and insomnia, among other conditions. While dependency with continued use has been the subject of much concern over this type of medication, other literature has suggested an increased risk of cognitive impairment with chronic use of benzodiazepines. The nature of the cognitive changes and the domains of cognitive function most likely to be affected have differed across various studies. Here we describe the associations between measures of various domains of cognitive functioning and benzodiazepine use in 2879 older Canadian adults from the Canadian Study of Health and Aging (CSHA; 64.3% female, mean age 81.0 years, SD=7.44). These people underwent a comprehensive medical and psychosocial evaluation that included a record of medications used, in addition to a complete personal and medical history. The CSHA was a community-based epidemiological study of the prevalence of dementia and its associated risk factors in over 10,000 Canadians. Benzodiazepines were classified according to their half-life: short (under 12 hours), medium (12 to 40 hours) or long half-life (over 40 hours); 35 elderly people were excluded since they were taking more than one class of benzodiazepine. A comprehensive neuropsychological battery that assessed the major domains of cognitive functioning was administered to all participants who completed the CSHA clinical assessment. Neuropsychological test scores for the domains of short- and long-term memory, abstract reasoning, judgement, visuoconstruction, and language formed were the primary independent variables, while gender, age, and years of education were used as covariates in logistic regression models predicting use of each class of drug. Education was not a significant covariate for any analysis. Gender proved to be a significant covariate in the case of the medium-half life drugs, but not for the other two classes. Age was a significant covariate for the majority of test scores for the short and long half-life drugs. After controlling for the covariates, the results showed a broader range of cognitive impairments with the use of short half-life benzodiazepines than with the medium half-life or the long half-life benzodiazepine compounds. Six cognitive measures, assessing abstract reasoning and comprehension, verbal fluency, verbal memory, and visuoconstruction skills (BlockDesign), showed poorer performance among those who used short half-life benzodiazepines, two measures, those of abstract reasoning and comprehension, showed impaired performance by those using medium half-life benzodiazepines, and three measures, for abstract reasoning, verbal memory, and visuoconstruction skills, showed lower performance by those taking long halflife benzodiazepines. Wechsler Similarities, the measure of abstract reasoning, was the only showing significant differences common across all three drug class models. Results are discussed in terms of both the relative extent of lower neuropsychological test scores and the context of increasing evidence of impaired functioning associated with benzodiazepine use.

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