Antidepressants May Be Linked To Heightened Risk For Dementia
Antidepressants are one of the most prescribed classes of drugs available, but new Canadian research published in the journal Depression and Anxiety indicates these drugs may be contributing to Alzheimer’s and other forms of dementia.
The findings of the study suggest commonly used SSRIs (selective serotonin reuptake inhibitors) such as Prozac may be linked to a twofold increase in risk of developing a form of dementia later in life. The effect was even more pronounced for those who began taking antidepressants before the age of 65.
The study isn’t able to establish a clear and direct link between the use of antidepressants and dementia, but it is enough to warrant concern and further research – especially as SSRI use continues to increase.
Currently, SSRIs are being used for a wide range of ailments that the medications often are not intended to treat, such as insomnia, pain, and hot flashes.
“They’re being prescribed ‘off label,’ meaning for non-depression related situations. They’re being prescribed to very young children and to the very old,” said Dr. Darrell Mousseau, a professor in the department of psychiatry at the University of Saskatchewan and the study’s senior author. He also holds a research chair in Alzheimer’s and related dementia jointly funded by the Alzheimer’s Society of Saskatchewan and the Saskatchewan Health Research Foundation.
“They’re almost becoming the antibiotic of this century: ‘If you’ve got a disease, take an SSRI. It’s going to help you in one way, shape or form.’”
While this treatment of SSRIs is worrisome, Mousseau also emphasizes that the drugs can be beneficial when used properly.
“They certainly do benefit some people,” he said. “But we do find this association (with dementia) and, if nothing else, I think the discussion needs to begin.”
The latest estimates indicate up to 5.4 million American’s currently live with Alzheimer’s – one in nine of all people over 65.
The number of people affected by Alzheimer’s is expected to keep climbing in coming years, which has encouraged researchers to hunt for risk factors to encourage early identification and intervention. Several studies have found evidence that depression may be one such risk factor. However, as Mousseau says, “not everyone who has depression gets Alzheimer’s disease, and not everyone who has Alzheimer’s has had depression.”
This caused Mousseau to wonder if it wasn’t depression contributing to Alzheimer’s, but the medications typically used to treat depression. In addition to the possible link between depression and Alzheimer’s, Mousseau notes that a specific class of molecules in the brain called monoamines – which include serotonin and noradrenaline – are among the first to die during the brain changes leading to Alzheimer’s.
“All of these anti-depressants act on these monamines,” added Mousseau. “It was just a logical step to look into what these drugs might be doing.”
For the study, the team reviewed medical literature to identify five relevant studies from an initial pool of over 4,000 initial potential studies. In total, the five studies included almost 1.5 million people.
According to the analysis, people with dementia were approximately twice as likely to have used antidepressants compared to those without dementia. When the team limited the pool of subjects to those under 65, the risk was even higher – almost threefold.
The link was strongest with SSRIs, but other forms of antidepressants were also linked with increased risk for dementia.
The research was limited and could not discern whether dose or duration of antidepressant usage had an influence on the risk for dementia.
“But there is something to this association, even if it is not clear what it means,” said Dr. Joel Paris, past chair of psychiatry at Montreal’s McGill University.
These findings go against another U.S. study published two years ago, which found the SSRI citalopram actually reduced the production of the brain plaques associated with Alzheimer’s. However, the team believes further research can shed insight into these discrepancies.