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Treating Depression May Reduce Dementia Risk
Studies show a link between the two, and researchers are looking at how they interact. Here’s what you can do now to lower your risk of both
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Depression and dementia are both debilitating brain illnesses. Research now shows they have an unhealthy relationship, too. Depression at any adult age is linked to a higher risk of dementia, and studies suggest that the association is stronger when depression occurs later in life.
The 2024 Lancet Commission report on dementia prevention includes depression as one of 14 modifiable risk factors, alongside factors like hypertension and inactivity. Specifically, in an analysis of 18 studies published in eClinicalMedicine in 2025, depression in late life — commonly defined as age 65 years and older — nearly doubled dementia risk.
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Researchers are still untangling how the two are related, but here’s what we know: “Depression is a high-stress state, and we know that stress has negative effects on the brain,” says Dr. Jordan Karp, professor and chair for the department of psychiatry at the College of Medicine at the University of Arizona in Tucson and clinical service chief for behavioral medicine at Banner – University Medical Center in Tucson.
Plus depression can change behaviors in ways that increase dementia risk. “People with depression may be physically inactive and using more alcohol or other substances, both of which can contribute to dementia risk. People with depression may not be sleeping well, which is an established risk factor for cognitive decline,” he says.
Shared risks, overlapping symptoms
Up to 41 percent of people with dementia also have depression, so diagnosing can get tricky. Some symptoms of depression, like a loss of interest in activities, anxiety and sleep problems, can be signs of what’s called mild behavioral impairment (MBI), an early flag of cognitive problems that may be years down the road.
“It’s not common for depression to show up for the first time in later life. When there is a new onset of depression, it often signals that there might be some underlying changes in the brain. MBI represents those early brain changes associated with neurodegeneration,” says Ruth Morin, a clinical neuropsychologist at Hoag Hospital in Newport Beach, CA.
Treating depression may reduce dementia risk
The good news is that treating depression may lower a person’s risk of dementia. A large study of more than 46,000 people ages 50 to 70 years with depression showed that those who were treated with medication, psychotherapy or both had about a 30 percent lower risk of developing dementia during nearly 12 years of follow-up compared with those who were untreated. Results were published in Alzheimer’s & Dementia in 2024.
How depression may affect the brain
Depression may change brain functions and structure in ways that can contribute to dementia risk. These include:
Stress: Chronically elevated levels of cortisol, the body’s main stress hormone, may shrink areas of the brain, like the hippocampus, which is responsible for learning and memory.
Inflammation: Many people with depression have chronic, low-grade inflammation, which is linked to changes in brain function and may contribute to problems with memory, learning and mood.
Vascular problems: Depression is linked to changes in the cardiovascular system, including inflammation and blood-vessel damage, two risk factors for dementia.
Altered cell connections: Brain cells can lose some of their complex connections, particularly in areas related to mood and brain function. The brain may process information and regulate emotions less efficiently.
So if you think you may have depression, talk to your health care provider. Symptoms may include feeling disengaged from others — or being told by others that you appear to be pulling away, a lack of interest in activities you used to like, and changes in energy or sleep. Intervening early may help reduce the risk of dementia.
“By the time someone comes into my office with memory changes, their spouse might be saying, ‘For the last three years, he won’t get off the couch when he used to be super social.’ So probably three years ago would have been the time to go into the doctor and talk about those changes,” Morin says.
Healthy habits can help treat depression and may help lower dementia risk, too. Research shows that engaging in leisure activities — playing tennis, reading, hanging with friends — can ease symptoms of depression. And being social can also reduce your risk of cognitive decline and dementia.
“What can you do to engage with your life? Can you enlist a family member to help with medication? Maybe you can’t play golf with your friends, but maybe you can go to the club and sit with them for lunch afterwards,” Morin says.
Ongoing exercise can also do double duty as both prevention and treatment for depression. “With successful treatment people are more likely to be social and engage in activities. They may be more invested in taking care of their health, and they may be more motivated to be physically active. Prescribing behavioral changes like increased physical activity and spending meaningful time with others is for some people as important as any medication,” Karp says.
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