Share on PinterestHaving more than one mental health condition may substantially increase dementia risk, according to a new study. Tatiana Maksimova/Getty Images
- Past research has linked certain mental health conditions, such as depression and anxiety, to an increased risk for dementia.
- A new study has found that people who have multiple mental health conditions have a higher risk of developing dementia than those with one.
- Coexisting mood and anxiety disorders correlated with increased dementia odds of up to 90%.
- Researchers report that this risk percentage increases with each additional concurrent mental health disorder.
Past research has linked certain mental health conditions, such as depression, anxiety, post traumatic stress disorder (PTSD), and bipolar disorder to an increased risk for dementia — a neurological condition impacting about 57 million people globally.
Scientists believe that mental health issues may be correlated with a higher dementia risk due to chronic inflammation and structural brain changes, as well as an increase in the protein amyloid-beta in the brain, which is considered a hallmark of a type of dementia called Alzheimer’s disease.
Now, a new study recently published in the journal BMJ Mental Health reports that people who have multiple mental health conditions have a higher risk of developing dementia than those with one.
Researchers say this risk percentage increases with each additional concurrent mental health disorder.
Having 2 psychiatric disorders doubles dementia risk
For this study, researchers analyzed health data from more than 3,600 adults ages 45 and older from the psychiatry department of Bicêtre Hospital in France. Study participants all had at least one psychiatric disorder, including depression, anxiety, psychosis, substance use disorder, personality disorder, or bipolar disorder. Researchers also recorded whether or not participants had dementia or cognitive impairment.
At the study’s conclusion, scientists found that participants with two psychiatric disorders were twice as likely to be diagnosed with dementia than those with only one. Those with three mental health issues were four times more likely to have dementia. And those with four or more psychiatric disorders had an 11 times greater chance of being diagnosed with dementia than those with one mental health concern.
Researchers highlighted that a combination of coinciding mood and anxiety disorders correlated to increased dementia odds of up to 90%.
As this is an observational study, no causation can be determined for certain. However, in the study, researchers state they believe their findings “highlight the need for targeted dementia screening and preventive actions in patients developing more than one psychiatric disorder, particularly those with both anxiety and mood disorders.”
Mental health screening and prevention strategies
Medical News Today spoke with Michael S. Okun, MD, director of the Fixel Institute for Neurological Diseases at the University of Florida Health and author of The Parkinson’s Plan, about this study.
“This study revealed that the more psychiatric conditions a person has, the higher their odds of dementia, with mood and anxiety disorders together carrying the greatest risk,” Okun commented. “This data should point us in the direction of screening and prevention strategies, especially for those most vulnerable.”
“My first reaction when reading the study was how striking the data [was] showing that the dementia odds climbed dramatically and as psychiatric disorders stacked up,” he continued. “The odds skyrocketed in those with four or more conditions.”
The cause or an early sign?
“It is important to continue the search for health issues tied to dementia because psychiatric and cardiovascular factors may serve as early warning signs and these could open the door for prevention. The next step should be replication as well as larger and possibly multicenter studies using biomarkers and imaging to confirm whether psychiatric co-occurrence is a causal pathway or an early marker of dementia.”
— Michael S. Okun, MD
But why do mental health conditions raise dementia risk?
MNT also spoke with Gary Small, MD, chair of psychiatry at Hackensack University Medical Center in New Jersey, who commented that he was not surprised by the study’s findings.
“Previous research has confirmed depression as a risk factor for dementia,” Small explained. “This new investigation demonstrating the degree of the effect of multiple psychiatric disorders is remarkable, and the findings raise questions about the reason for these results. We know that late-life dementia has a gradual, insidious onset and that a patient’s self-awareness of their cognitive decline can trigger emotional reactions that lead to depression, anxiety, and other mental disorders.”
“Another possible explanation is that the underlying brain disease leading to dementia also contributes to mood symptoms,” he continued.
“Our UCLA research team performed brain scans of older adults using positron emission tomography (PET) to visualize amyloid plaques and tau tangles, the abnormal protein deposits of Alzheimer’s disease. We found significantly higher abnormal protein levels in study volunteers with late-life depression compared with controls, suggesting that these brain abnormalities linked to Alzheimer’s dementia may also contribute to major depression in older adults,” he explained.
Small said it’s important for researchers to continue to find other health issues that may increase a person’s risk of developing dementia, as dementia is the most common mental disorder of late life.
“The risk for developing Alzheimer’s disease and other forms of dementia is 10% for people ages 65 and older, and that risk approaches 40% by age 85 years. The 2024 Lancet Commission has identified 14 modifiable risk factors for dementia, and knowledge of these factors empowers people to lower their future risk for the disease.”
— Gary Small, MD
As for the next steps for this research, Small said further study should illuminate the details of these known risk factors and reveal others not yet discovered.
“We need research that elucidates whether effective treatment of depression, anxiety, and other conditions will reduce future risk of dementia,” he added.
