Depression in Alzheimer’s has different risk factors than depression in older adults without the disease, finds a major new study in the Journal of Alzheimer’s Disease. The University of Bristol-led research looked at over 2,000 people with the disease to explain why current anti-depressants are ineffective for people living with depression in Alzheimer’s.

Depression in dementia is common, up to 16% of people with Alzheimer’s disease develop depression but it is not known why it is more common in those living with Alzheimer’s than in older adults without dementia. Individuals with depression in dementia also appear to have different symptomatology with less symptoms of appetite reduction and thoughts of life not being worth living. Currently available anti-depressants are ineffective making the depression difficult to treat.

Alzheimer’s disease is a physical disease that affects the brain and, according to charity Alzheimer’s Society, who co-funded the research, 900,000 people in the UK have a form of dementia.

Researchers from Bristol’s Dementia Research Group wanted to investigate whether risk factors known to increase the risk of depression in adults without dementia, also increased the risk of depression in those with Alzheimer’s, to identify possible new treatment targets.

Using data from three major dementia-focused cohorts, the team analysed depression ratings on 2,112 individuals with Alzheimer’s and compared this with data from 1,380 participants with normal cognition.

Their results showed that risk factors for depression in Alzheimer’s appear to differ to those for depression, supporting suggestions of a different pathological process, although a family or past history of depression was the strongest individual risk factor suggesting a possible genetic predisposition. Individuals with depression in Alzheimer’s were more likely than those with the disease who are not depressed to develop apathy and other non-memory symptoms of Alzheimer’s disease.

Dr Lindsey Sinclair, the study’s lead author and a Clinical Research Fellow at the University of Bristol’s Dementia Research Group, said: “The incidence of depression is increased in those with Alzheimer’s compared to older people without dementia, it is extremely distressing for patients and may make caring for them more challenging. It is important to try to understand what changes are present in the brains of those with Alzheimer’s disease who also have depression as this may help us to identify possible new treatment targets.

“Our findings showed that depression in Alzheimer’s disease appears to have different risk factors to depression in those without dementia. This adds weight to previous suggestions that depression in Alzheimer’s may have a different underlying cause to depression in those without dementia and may explain why antidepressants are not effective in treating it.”

Dr Richard Oakley, Associate Director of Research at Alzheimer’s Society which co-funded the study, added: “Depression has a negative effect on your day-to-day life, and if you have Alzheimer’s too it can be a double blow.

“We know that depression is more common in people with Alzheimer’s disease than in healthy adults but we don’t know why. This research suggests that there may be different reasons why someone living with Alzheimer’s disease develops depression.

“This in turn may explain why antidepressants are not as effective for people with both depression and Alzheimer’s disease, and so we may need to think differently about how we treat it.

“More research is needed to understand the link between the two conditions so we can better treat and support those struggling with their mental health.

“If you, or a person you love, is dealing with depression alongside dementia, please make an appointment with your GP or get in touch with Alzheimer’s Society. We vow to help end the devastation caused by dementia, providing help and hope for everyone affected. For more information or to donate visit alzheimers.org.uk.”

The study was supported by funding from a number of organisations including the Alzheimer’s Society, Elizabeth Blackwell Institute, and Wellcome.
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Full bibliographic information
Published on 22/03/2023 by the University of Bristol.
‘Characterization of depressive symptoms in dementia and examination of possible risk factors’ by L Sinclair et al. in the Journal of Alzheimer’s Disease [open access]