“Use it or lose it” is a catch-cry that applies to the brain as well as the body. For some time now, researchers have known that, in general, people who stay more mentally active throughout their lives tend to have a lower risk of developing dementia in their later years. Why this is has been much less clear.
Research my group has recently published sheds light on this interesting and potentially very powerful biology. We started off with a broad interest in “cognitive lifestyle”, a term used to describe a person’s lifetime patterns of learning new things, engaging with others, and challenging the mind. In this study, cognitive lifestyle was measured by asking each person about their educational experiences, classifying how complex and demanding the main job was during their working years, and more currently, how often they were catching up with family and friends.
This research was only possible by working with one of the largest datasets of its kind, the Cambridge-based Cognitive Function and Ageing Study (CFAS). The study has more than 13,000 participants – older individuals who have now passed their 14th year of ongoing follow-up.
Initially, we used this dataset to confirm that living a “more active cognitive lifestyle” does indeed lower your risk of dementia. We found that, on average, people who had either completed more years of education, worked in a more complex or mentally demanding occupation, or were more socially engaged with family and friends had a 40% lower chance of developing dementia over the long term.
Next, we analysed tissue from all 329 people in the study who had died during the 14 years and donated their brain to science. Since the most common cause for dementia is the build up of Alzheimer’s disease, our first test asked one of the more obvious questions: do more cognitively active people simply develop less Alzheimer’s pathology?
The answer was a rather clear no. We found no difference between those with an active versus impoverished cognitive lifestyle across almost a dozen different brain tissue markers for Alzheimer’s disease.
Going even deeper
We then carefully selected a subgroup of 72 brains for very detailed microscopic analysis. This group comprised of 36 people with either an active cognitive lifestyle or impoverished cognitive lifestyle, but who were otherwise matched on many different clinical and personal details. This allowed us to feel confident that any differences we found were mainly associated with the person’s cognitive lifestyle.
This final analysis revealed two very interesting results. First, a more active cognitive lifestyle in men was strongly linked to lower frequency and severity of vascular disease in the brain. In particular, mentally active men had about 80% lower chances of disease in their brain’s microscopic blood vessels. And this didn’t appear to be explained by differences in other lifestyle habits such as smoking, obesity and so on.
Second, in both men and women, those with a more active cognitive lifestyle had more neurons (brain cells) and thicker cortical tissue in the frontal lobe part of the brain. The frontal lobe is responsible for many of the mind’s “executive processes”, such as planning, strategising, controlling responses, switching attention and problem solving. So maintaining a more mentally “switched-on” lifestyle over many years may lead to structural benefits in the brain towards the end of life.
So, what does it mean?
Our research suggests that there could be a number of different pathways in the brain by which an active cognitive lifestyle leads to reduced dementia risk.
In men, a degree of protection against microscopic vascular disease in the brain is implicated. In both men and women, there’s evidence of neuroplastic changes in the frontal lobe - greater mental activity over time seems to be associated with either growing more brain cells, or losing fewer cells, and perhaps with more connections between brain cells. Together these kinds of changes translate to an increase in brain volume in this very particular part of the brain.
Like any good research, this study stimulates many more questions about the links between cognitive lifestyle, the brain, and dementia that will need further investigation. But it does emphasise the potentially powerful effects that mental habits have on brain structure and function.
In the context of an ageing society with truly alarming dementia predictions over the next decades, our research adds yet more hard evidence to the idea we should be promoting and providing opportunities for challenging, rich and engaging cognitive lifestyle activities for our older citizens as a way of maintaining optimum brain health and minimising dementia risk.
Associate Professor Michael Valenzuela is the author of Maintain Your Brain, published by ABC Books.