An early sign of Alzheimer’s disease
Having depression is known to increase a person’s risk of developing dementia. But new research, supported by Barts Charity, shows that depression is also an early indicator of dementia – particularly in older people.
Researchers at the Centre for Preventive Neurology, established with our funding in 2017, found that while people with depression were more likely to develop dementia than those without, the chance of someone experiencing depression increased steadily in the ten years leading up to a dementia diagnosis. If depression were causing dementia, it would be expected that those who’ve had depression for longer would be at a greater risk. But the team found the reverse to be true. The link between depression and dementia became stronger closer to the time of dementia diagnosis.
In people over the age of 65, depression might indicate the early signs of Alzheimer’s disease – the most common cause of dementia in the UK.
Depression roughly doubled the risk of developing dementia
The team of researchers analysed the health records of nearly 500,000 participants from the UK Biobank (a source of biomedical data for health research in the public interest), comparing those with and without diagnoses of both depression and dementia. They wanted to establish whether depression was causing dementia or if early dementia was causing depression. They did this analysis using MRI brain scans of more than 41,000 Biobank participants to examine if brain patterns linked to depression were different in older adults compared to younger adults with depression.
They found the link between dementia and depression was highly specific. Even after adjusting for other variables including poverty, gender, education, smoking and social isolation, they still found that depression roughly doubled the risk of developing dementia. They also found that severe depression was associated with greater dementia risk.
In people aged 65 and over, depression was associated with changes in brain regions linked to Alzheimer’s disease. However, young people with depression didn’t show the same patterns of brain changes, suggesting that depression may affect brain health differently at different ages.
“Depression is often viewed as a ‘modifiable’ risk factor for dementia, but this may need to be reevaluated in light of this study. We hope that the findings will lead to a more nuanced approach when considering whether treating depression could be a way of preventing dementia. Our results suggest that while treating depression earlier in life might have a small benefit on brain health, there may be more to be gained from using depression in later life as a way of identifying people who are in the early stages of dementia. An awareness of this could help to improve access to timely diagnosis and treatment of dementia.”Professor Charles Marshall, Professor of Clinical Neurology, Centre for Preventive Neurology, Queen Mary
Supporting an ageing population in East London
“We are proud to have supported this research from the Centre for Preventive Neurology, revealing the complex links between dementia and depression. With an increasingly ageing population, this research could have a positive impact on the health of our East London community, and beyond, by identifying patients in the early stages of dementia so they can start crucial treatment sooner.” Victoria King, Director of Funding and Impact at Barts Charity.