The early life dementia indicator you may have missed

The state of your mental health in early adulthood is linked to your risk of developing dementia in later life, according to a study.

The effects of dementia are a painful reality for almost half a million older Australians, and health professionals say that number is set to explode if treatments are not found. Alzheimer’s disease accounts for more than 70 per cent of dementia cases, but other types include vascular dementia, frontotemporal dementia and Lewy body disease.

Predicting the condition ahead of time can be tricky, and the search for early markers of dementia is a constantly evolving field.

The link between depression – especially later in life – and dementia is well established. Depression is also common among those suffering from dementia, making it unclear whether the depressive symptoms caused the dementia or the other way around.

Read: Five myths about depression

But now, researchers from the University of California-San Francisco (UCFSF) have demonstrated a link between depression in early adulthood and a decline in cognitive function later in life.

The research team used statistical methods to predict the average trajectories of depressive symptoms for around 15,000 participants aged between 20 and 89.

Following these trajectories, they found that in a group of around 6000 older participants the odds of cognitive impairment were 73 per cent higher for those who had experienced depressive symptoms in early adulthood. Depression in later life resulted in an increase in dementia risk of 43 per cent.

While cautioning the need for further study, the researchers hope this may provide another avenue for early dementia detection. It’s still not entirely clear at this stage how depressive symptoms affect the brain as it ages.

Read: Chronic pain causes brain changes that increase depression and anxiety

“Several mechanisms explain how depression might increase dementia risk,” says lead author of the study Dr Willa Brenowitz.

“Among them is that hyperactivity of the central stress response system increases production of the stress hormones glucocorticoids, leading to damage of the hippocampus, the part of the brain essential for forming, organising and storing new memories.”

Dr Brenowitz says the degree, intensity and duration of depressive symptoms are all factors in the risk of developing dementia.

“Generally, we found that the greater the depressive symptoms, the lower the cognition and the faster the rates of decline. Older adults estimated to have moderate or high depressive symptoms in early adulthood were found to experience a drop in cognition over 10 years,” she says.

Read: Just 25 grams a day almost doubles dementia risk: study

In Australia, around one in five people will experience symptoms of depression and anxiety in their lifetime. Depressive symptoms are most common in young adults aged between 18 and 24 and it’s estimated that about 54 per cent of sufferers never seek treatment.

The researchers say addressing the symptoms of depression earlier in life may prove helpful in reducing the risk of dementia in later life, but warned against seeing depression in early life as a guarantee of dementia.

“In late life, it’s hard to tell the chicken and the egg – which came first? People who develop dementia often have a trajectory of 20 years of decline, so it’s hard to pinpoint,” Dr Brenowitz says.

“Is this an early dementia syndrome, or is this due to other risk factors for dementia, such as vascular disease?”

Have you ever noticed a link between depression and dementia? Is there a younger person in your life who could benefit from help with their mental health? Let us know in the comments section below.

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Written by Brad Lockyer

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