Depression is linked with a higher risk of dementia later in life, according to a study published in the journal eClinicalMedicine.
“Our study shows that depression is linked to an increased risk of dementia in both midlife and late life. This highlights the importance of recognising and treating depression across the life course, not just for mental health, but also as part of a broader strategy to protect brain health. Public health efforts need to emphasise preventative brain health, including scaling up access to effective mental health care,” said Jacob Brain from the Institute of Mental Health and School of Medicine at the University of Nottingham, UK.
Dementia affects 57 million people worldwide. There is currently no cure, so identifying and treating potential risk factors — such as depression — is a significant public health priority. According to the authors, the link between depression and dementia is complex. It may include chronic inflammation, hypothalamic-pituitary-adrenal axis dysregulation, vascular changes, alterations to neurotrophic factors, and neurotransmitter imbalances. In addition, shared genetic and behavioural factors may also increase the risks.
Previous studies show that people with depression are more likely to develop dementia later in life, but researchers don’t know when depression matters most: it could be if patients have depression in midlife – in your 40s or 50s, or if depression that appears later in life – in your 60s or beyond.
The team gathered and reviewed all the available data from systematic reviews looking at the link between depression and dementia. They then went a step further and re-analysed data from the individual studies within those reviews, plus they added in newer studies that were not included in the earlier work.
“We specifically focused on the timing of when depression was measured, whether it was measured in midlife or later life, and calculated how much it increased the risk of developing dementia. This essentially allowed us to provide a more accurate and up-to-date picture of how depression at different life stages is linked to dementia risk,” said Jacob Brain.
The results show that depression later in life is more likely to be linked with dementia. “Our findings raise the possibility that depression late in life may not just be a risk factor, but it could also be an early warning sign of dementia beginning to develop. By clarifying this timing, our work helps guide future research, treatment, and prevention strategies,” concluded Mr Brain.