Higher Rates of Antidepressant Use Associated With Alzheimer’s

According to a study published online last month in the International Journal of Geriatric Psychiatry, patients with Alzheimer’s disease (AD) are prescribed antidepressants at a much higher rate than the general population.

Researchers at the University of Eastern Finland compared data on prescription rates for 62 104 community-dwelling individuals with a confirmed diagnosis of AD with that of the same number of sex- and age-matched controls without AD. Using data from the Finnish register-based cohort study called the Medication Use and Alzheimer’s Disease (MEDALZ), they analyzed information spanning a 3-year period, from nine years before diagnosis to four years post-diagnosis. They also investigated prescription rates of specific groups of antidepressant medication.

Results show that patients with AD – which accounts for approximately 70% of dementia cases and is the most common form – received initial antidepressant prescriptions about twice as often as controls for the duration of the study period. The rate was highest in the six months after AD diagnosis, when it jumped to five times that of the comparison group, and higher rates of antidepressant use were observed in the AD group even nine years prior to the AD diagnosis.

This finding could not be accounted for by comorbid psychiatric conditions, as these were actually found to be lower among the AD group than in the control group. The most frequently prescribed medications were selective serotonin reuptake inhibitors (SSRIs), followed by mirtazepine. The latter is also a treatment for insomnia, which is a common symptom in AD.

Most AD patients have behavioral and psychological symptoms of dementia (BPSDs), such as depressive symptoms, aggression, agitation, and hallucinations. Approximately 20 -42% of AD patients suffer from depressive symptoms, which often precede the AD diagnosis, then increase in the first years post-diagnosis, and decrease over the course of disease.

Previous research shows that 22-47% of community-dwelling individuals with dementia use antidepressants, and rates of use are three times higher among AD patients compared to people without dementia.

However, there is mixed evidence regarding the efficacy of antidepressants for depressive symptoms in patients with dementia, note the researchers of the current study. Complicating the clinical picture is the overlap in symptoms between depression and AD. For example, “clinical depression may impair cognitive performance, and thus, depressive symptoms and early cognitive decline may be difficult to discriminate,” they wrote.

They expressed concern about their findings, because antidepressants have been linked with adverse events among the elderly, such as elevated risk for falls and fractures. Considering the controversial efficacy of antidepressants in treating BPSD symptoms, along with their high rate of use among AD patients, this practice could put older patients at risk for severe adverse events.

“Frequent monitoring of treatment and balancing between benefits and risks associated with antidepressant use should be encouraged in this frail population,” the authors wrote. Additionally, clinicians should carefully monitor older patients with depressive symptoms to potentially identify cognitive decline as early as possible.

Reference

Puranen A, Taipale H, Koponen M, et al. Incidence of antidepressant use in community-dwelling persons with and without Alzheimer’s disease: 13-year follow-up. Int J Geriatr Psychiatry; published online February 28, 2016. DOI: 10.1002/gps.4450.

Reference