Cognitive decline ‘begins in your 40s’, scientists warn – 6 ways to stem the brain drain

COGNITIVE decline can begin as early as your 40s, scientists say.

Though much research into loss of cognitive function focuses on older age groups, researchers from University College Cork argued that a major shift in the way your brain ages occurs between the ages of 40 and 60.

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As such, more research should be dedicated to this historically understudied period of life, they said.

“Middle age is associated with specific and modifiable risk factors for future dementia risk,” the authors, including neuroscientist Yvonne Nolan of APC Microbiome Ireland at University College Cork, wrote.

“We encourage giving this previously understudied period of life renewed consideration.”

Most studies of brain health and cognitive decline focus on older age groups, but by this time, interventions or treatments may not be as effective as they would have been early on.

Screening for risk of future cognitive decline could help could mean that people will be able to access treatment earlier, when it will be more effective, researchers said.

A better understanding of how the brain shifts during middle age might also help identify new targets for therapy, they added.

During middle age, the brain undergoes significant molecular, cellular, and structural changes.

Many of these changes have been linked to cognitive decline, which has also been shown to accelerate during middle age.

One in 10 people who experience mild cognitive impairment go on to develop dementia, according to Alzheimer’s Research UK.

Lead by Dr Sebastian Dohm-Hansen, study authors wrote: “There is good evidence to suggest that the human brain undergoes non-linear structural and functional changes during middle age that have implications for cognitive functioning, and variation in these processes could account for individual trajectories in cognitive ageing.” 

What happens to your brain during middle age?

You brain undergoes a number of structural changes during middle age, according to the research published in the journal Trends in Neurosciences.

Your hippocampus, the part of your brain involved in memory and learning, shrinks. Connections between different parts of your brain also decrease, according to the researchers.

“The fourth and fifth decades of life may be a turning point in the organisation of brain networks, characterised by optimal efficiency, system segregation, and modularity, followed by accelerated decay of these properties,” Dr Dohm-Hansen wrote.

In women specifically, menopause can be defining feature of middle age that brings with it changes to the brain, “some of which have implications for cognitive ageing”, according to the author.

Gene expression – the process by which specific genes are activated to produce proteins – also shifts in middle age, both in the brain and other parts of the body.

More immune-related genes are activated between your 40s and 60s, and fewer synaptic genes, studies reviewed by the research team suggested.

Other research suggested that changes in other parts of the body may predict brain health and function.

“Factors in systemic circulation – mainly proteins secreted by various organs – are understood to mediate brain ageing in terms of cognition, plasticity, adult neurogenesis, and neuroinflammation,” Dr Dohm-Hansen went on.

How to keep your brain healthy in middle age

The review also delved into ways in which people could stave off the ‘brain drain’ of middle age.

According to Dr Dohm-Hansen, there is some evidence that exercise can help your brain age healthily.

The researchers pointed specifically to aerobic exercise, which refers to cardio exercises that raise your heart rate and make you breathe faster than normal.

According to NHS Inform, moderate aerobic activities include a brisk walk, cycling, swimming, dancing and tennis.

“Meta-analyses of exercise interventions – especially aerobic – have suggested that exercise may slow down age-related volume loss in the left hippocampus of healthy older adults and improve various measures of white matter integrity in frontal and temporal lobe tracts across the adult lifespan, including during middle age,” Dr Dohm-Hansen wrote.

“This is particularly relevant in light of the accelerating decline in hippocampal volume and white matter volume beginning in midlife.”

He added that higher levels of physical activity was linked to less memory decline in middle-aged and older adults.

But researchers noted that more research is needed to show a clear link between exercise and lower levels of cognitive decline.

Further research is also needed to investigate differences in brain ageing between men and women, as there are higher rates of dementia in women, according to researchers.

“Ultimately, scientists will want to find novel therapeutic targets to mitigate unhealthy cognitive ageing,” Dr Dohm-Hansen said.

“We argue that applying recent trends in ageing research to this period of life could reveal novel biomarkers and possible interventions to combat cognitive decline in an increasingly older global population.”

According to the NHS, leading a healthy lifestyle can reduce your risk of developing dementia when you’re older.

Aside from exercising regularly – at least 150 minutes of physical activity over a week – you can also try:

• Eating a balanced diet (which includes five portions of fruit and veg per day)
• Maintaining a healthy weight (a BMI score of between 18.5 and 24.9)
• Keeping alcohol within recommended limits
• Stopping smoking
• Keeping your blood pressure at a healthy level (between 90/60mmHg and 120/80mmHg)