MADRID – Elderly patients who develop dementia often are on an antidepressant when dementia is diagnosed, and unexpectedly antidepressant use during the 3 years preceding diagnosis of dementia was linked with a significantly reduced mortality risk, Dr. Daniela Enache reported at the meeting, sponsored by the European Psychiatric Association.
Elderly Swedish patients who took an antidepressant for at least 1 year during the 3 years prior to their dementia diagnosis had a 13% relative reduction in mortality, compared with similar new-dementia patients who had not been on an antidepressant. The researchers tracked mortality for a median of 2.1 years following dementia diagnosis in 20,050 Swedes with a new dementia diagnosis using records from 2007-2013, said Dr. Enache, a psychiatrist and neurogeriatics researcher at the Karolinska Institute in Stockholm. The analysis adjusted for differences in age, sex, mental state, number of drugs used, and living conditions.
Mitchel L. Zoler/Frontline Medical News
Dr. Daniela Enache
The protective effect from 3 years of antidepressant use was strongest in people who went on to develop Alzheimer’s disease, the most common form of dementia in the study affecting 36% of all people who developed dementia. The findings also documented the relatively frequent antidepressant use by elderly people who develop dementia. In the series of people with newly diagnosed dementia of any type, 25% were on an antidepressant at the time of their dementia diagnosis, and 4,325 (22%) had used an antidepressant at least once during the 3 years prior to their diagnosis; 1,128 (6%) of the people diagnosed with dementia had used an antidepressant during all 3 years preceding their diagnosis.
Dr. Enache admitted that it was not clear why antidepressant treatment would have this mortality effect. One possibility is that the mortality benefit came from the action of antidepressants on behavioral symptoms. Or antidepressants could have a biological effect, such as reducing production of amyloid beta or affecting neurogenesis and brain plasticity. A third possibility is that antidepressant use is a marker for overall better health care.
Whatever the explanation, the finding provides reassurance that antidepressant treatment is safe in elderly patients who are at risk of developing dementia, she noted. And patients newly diagnosed with dementia should be screened for depression, although Dr. Enache stressed that antidepressants can be prescribed for other reasons, such as anxiety or behavior problems.
All types of antidepressants had this mortality effect: tricyclics, selective serotonin reuptake inhibitors, and other types. Use of antidepressants was roughly similar across various dementia diagnoses, ranging from 22% of patients with mixed dementia and 23% of those with Alzheimer’s disease to a high of 32% among patients with Parkinson’s disease dementia.
The researchers used data collected in the national Swedish Dementia Registry, which includes about 90% of patients treated at Swedish memory clinics, along with data from the national Prescribed Drug Registry. The average age at time of dementia diagnosis was 78 years. Following Alzheimer’s disease, the other most common diagnoses were mixed dementia, in 25%, and vascular dementia, in 19%.
Dr. Enache had no disclosures.