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As we reach our forties and fifties, we start to notice a few changes with our brain. We forget things more easily, we experience more “tip of the tongue moments” and find it harder to stay focused or on task. We put it down to the fact that our speed of mental processing is slowing down. We may even have a couple of fleeting worrying thoughts that our brain might be showing the first signs of actual cognitive decline.

One of the biggest fears people express about ageing, is the loss of our mental faculties. That loss of that of course, has a significant impact on our ability to remain self-caring and independent.

Until now, the onset of actual cognitive decline has been thought to occur in our sixties. The clinical onset of Alzheimer’s disease typically occurs around age 65 or older, although it is well recognized that the actual condition slowly and silently develops over the preceding couple of decades. Brain scans can now show the pathological changes in younger brains, before the clinical signs of disease.
Those showing the greatest amount of pathological change in their brains are also known to be at greatest risk of developing clinical signs of dementia in later life.

Findings from a couple of studies (including a longitudinal study from Seattle, which has been following a group of 500 individuals since 1956) have suggested that cognitive decline did not start before the age of 60.
Those findings have now been challenged by a new study recently published in the British Medical Journal which has found that the age of onset of cognitive decline may be significantly earlier than previously thought: actually starting in our mid forties.

This study of 10308 men and women civil servants aged 45 to 70 years from London UK was set up to examine whether different age groups showed differing levels of cognitive decline over a ten-year period. The group underwent tests of memory, reasoning, vocabulary, phonemic and semantic fluency in three different assessments over the ten-year period.

The results of the study showed the following:

Between the age of 65 and 70, men on average showed a -9.6% decline in cognition,
women -7.4%. This was not unexpected.

However results of the younger age group age 45 to 49 also showed evidence of cognitive decline, albeit at a lower percentage; -3.5% cognitive decline for men and -3.6% for women.

The implications of this study suggest that we need to be taking a much closer note of how we are performing in midlife. Along with midlife obesity, high blood pressure and high cholesterol, our midlife cognitive function appears to be very important in determining how we will fare as we age.

If cognitive decline is picked up in our midlife, then at least that provides some valuable time to be putting into place specific strategies to to minimize any further decline and attempt to build cognitive reserve. What we don’t know (and requires further study) is whether midlife cognitive decline will lead to actual dementia – however it would seem prudent to do whatever we can, to keep our brains intact.

So what is the best thing we need to be doing in our midlife?

It’s all about maintain and improving brain function by adopting brain healthy lifestyles:

Eat healthily with a wide variety of green vegetables, fruit, lean proteins, seeds and nuts and keeping away from pies, pasties, cakes and biscuits, hot chips and fried foods.

Maintain a positive attitude to life. Being social engaged and active helps to keep stress levels down and stave off anxiety and depression.

Use your brain to learn new skills. Aim to include mental activities every day that are outside our usual habits. Card games, Sudoku, brain games, and apps are all useful.

Move your body. One of the biggest things we can do for our brain is to ensure we spend a minimum of thirty minutes every day doing some form of physical exercise – enough to get the heart rate up.

So next time you have a memory lapse, forget an appointment or lose your keys while it might simply a slower speed of processing, it could be an indication of a more serious reduction in your cognitive ability. So rather than ignoring it, be proactive and take the time every day to help restore your mental sharpness. Your brain may depend on it.


Singh-Manoux,A.et al Timing of onset of cognitive decline: results from Whitehall 11 prospective cohort study. British Medical Journal 2012; 344 doi: 10.1136/bmj.d7622

Dr Jenny Brockis

Dr Jenny Brockis is a medical practitioner and internationally board-certified lifestyle medicine physician, workplace health and wellbeing consultant, keynote speaker and best-selling author. You can now pre-order her new book ‘The Natural Advantage’ due for publication in October 2024.

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