Can antidepressants increase the risk of dementia?

Antidepressants and dementia: What are the risks?

The relationship between antidepressant use and the risk of dementia is complex and not fully understood. Research on the potential link between antidepressant use and dementia risk has yielded mixed findings.

Some studies indicate that antidepressants with high anticholinergic properties increase the risk of dementia, but not nonanticholinergic antidepressants do not. ^[1]

Other studies show that selective serotonin reuptake inhibitors (SSRIs) increase the risk of dementia, but there is a lower risk for patients treated with tricyclic antidepressants. ^[1] However, research conducted by Harvard medical school points to the increased risk of dementia-like symptoms following prolonged use of tricyclic antidepressants. ^[2]

Another study concluded that short-term antidepressant usage correlates with a higher risk of dementia, with the risk reducing after prolonged use. ^[1]

A 2018 study concluded that there was a significantly larger risk of contracting dementia following antidepressant therapy, recommending healthcare providers avoid unnecessary prescription of antidepressants to anyone with dementia-like symptoms. ^[3]

Many of the studies examining the antidepressant-dementia relationship are observational in nature, which means they can identify associations but cannot establish causation. Other mitigating factors, such as preexisting health conditions, lifestyle factors, and medication interactions, could contribute to the observed associations.

The reality is that antidepressants are ubiquitously prescribed. They are the most effective treatment for depression and numerous other mental health conditions, and whilst the findings of numerous studies suggest a correlation between antidepressant use and dementia, they are fundamentally inconclusive. ^[1]

How could antidepressants cause dementia?

Antidepressants, especially those that affect serotonin levels, can alter neurotransmitter balance in the brain. Chronic imbalances in neurotransmitters could potentially impact cognitive function and contribute to cognitive decline over time.

Some antidepressants might affect the cholinergic system, which plays a role in memory and cognitive function. ^[2] Disruption of this system could potentially contribute to cognitive impairment or dementia. In a study conducted by the University of Washington, anticholinergics were found to correlate with a 54% higher risk of causing dementia in people who used them for longer than three years, when compared with those who used them for three months of less. ^[2]

Another possibility is that observed association between antidepressant use and dementia risk could be due to reverse causation. ^[3] Individuals with early cognitive decline might exhibit symptoms of depression or anxiety, causing doctors to prescribe them SSRIs.

Final thoughts

The relationship between antidepressant use and dementia risk is complex and not fully understood. While some studies have suggested an association between certain antidepressants and an increased risk of cognitive decline or dementia, the evidence is not definitive.

However, whilst causation has not yet been proven, there is much literature pointing to a correlation between prolonged antidepressant use and dementia.

Any concerns you may have about antidepressant use and dementia should be brought up with your healthcare provider. They can provide guidance based on your individual needs and medical history.