The Shock Moment
I was listening to a podcast last week and my ears pricked up when I heard a neurophysiologist say “Alzheimer’s in now an optional disease. 40 years ago, it wasn’t.” Was this the most outrageous, or outstanding thing I had heard?
First I was outraged. Both my mum and my mother-in-law have Alzheimer’s Disease, so dementia is front of mind (pun intended!), especially if my wife and I have a higher genetic pre-disposition.
The interviewee continued, “Dementia is not part of the normal brain ageing process.” I recoiled again, but then recognised her point, dementia can be strongly correlated to ageing, without ageing being the cause. In other words, it could be linked to other damaging factors that accumulate as we age, specifically how we have lived (e.g. our lifestyle).
Next I was now vexed and started searchin for evidence to prove or disprove this point.
In the UK around 944,000 people are living with dementia, of which there are two-hundred subtypes, with Alzheimer’s Disease (AD) accounting for 60%, Vascular Dementia 15%, Frontotemporal (the type of dementia Bruce Willis has) 10% and Lewy Body 5%.
Our 2lbs brain has 86 billion neurons (roughly the number of stars in the Milky Way) and each neuron has 7,000 connections to other neurons. AD, the vast majority of dementia, starts with the loss of synaptic connections, which allow signals to be passed from one neuron to another. As the connections fail the neuron gradually dies and, when neurons in a chain die, messages can’t be delivered as effectively, which causes the thinking difficulties that underpin dementia. Other types of dementia, such as vascular, can be caused by reduced brain blood flow.
Less than 3% of AD is genetic. Certain genes increase the risk of dementia, the most significant of which is APOE-e4. We inherit two APOE genes, one from each parent. People have a 25% risk of carrying one copy of the APOE-e4 gene and a 2-3% risk of two. Having one APOE-e4 gene doubles or triples the AD risk and having two increase this eight to twelve-fold. But even with two, there is no certainty of AD and many people who don’t have an APOE-e4 gene get the disease.
The greater risk of dementia is from lifestyle, including exercise, diet and sleep, and environment. Most experts agree that lifestyle contributes significantly more than genetics.
That should be a relief, as many lifestyle risks are modifiable. In other words, there’s a lot we can do to lower the risk, or delay and reduce the impact of dementia, even if we have a higher genetic risk.
The Lifestyle Factors
The Lancet Commission on Dementia, published a report “Dementia prevention, intervention and care 2024”. This very recent and detailed study identified 14 lifestyle and environmental factors that impact on the relative risk of dementia. See https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(24)01296-0/fulltext
Summary of the Dementia Risk Factors
| Factor | Increase in Risk |
| Early Life (aged less than 18) | |
| Poor education | 60% |
| Midlife (aged 18 – 65) | |
| High blood pressure (in excess of 140mmHG) | 20% |
| Excessive (more than 21 units) alcohol consumption | 20% |
| Obesity (BMI greater than 30) | 30% |
| Smoking | 30% |
| Lack of exercise | 40% |
| Diabetes | 70% |
| High LDL Cholesterol | 30% |
| Traumatic brain injury | 70% |
| Depression | 120% |
| Hearing Loss | 40% |
| Later Life (aged over 65) | |
| Untreated vision loss | 50% |
| Social isolation | 60% |
| Air pollution | 10% |
Interestingly a good education in early life builds a cognitive reserve. Then in midlife managing weight (which also impacts on diabetes), cardiovascular health (including smoking, blood pressure and high cholesterol) and depression are important. In later life staying socially connected is key.
Together these 14 factors account for nearly half (45%) of all dementia cases. Where all are present, the dementia risk is over 6 times greater than where none exist.
The good news is that the potential for prevention is high, and this can be achieved by eliminating as many of these risk factors as possible.
To quote the Lancet Commissions “it is important to be cognitively, physically and socially active in midlife and later life.” People with healthy lifestyles have a lower risk of dementia and their dementia onset is also delayed, resulting in more healthy years, in other words, fewer years with dementia. A win win!
Most importantly, it is never too late to change behaviours. Even ceasing smoking later in life lowers the dementia risk – in fact the report concluded that the beneficial effect of stopping smoking was encouraging. Equally, the reduction in dementia risk was greatest for those who transition from being inactive to doing some physical activity.
One lifestyle factor that is of particular interest for me is exercise. Aerobic exercise increases the oxygen flow to the brain, which lowers the risk of all causes of dementia, especially Vascular. In addition, resistance exercise (i.e. strength training) has a very positive impact on cognitive function. Preliminary findings (see https://pubmed.ncbi.nlm.nih.gov/38823487/) show that it is highly protective, even amongst people with early onset dementia, as it induces structural brain changes that both reduce the risk of AD and mitigates its progression. And if performed at least twice per week for at least 6 months, RE can reverse the damage and improve cognitive function. In fact, these results were greatest for those already experiencing some elements of cognitive decline.
Another study in 2020 from the University of Sydney, showed that 6 months’ RE can help protect brain areas already vulnerable to AD (i.e. with mild cognitive impairment) for up to 12 months. (see https://www.sciencedirect.com/science/article/pii/S2213158220300206?via%3Dihub) Their message was that resistance training should become a standard part of dementia risk-reduction strategies.
Just to be clear, the other side of the coin is that however much you do to manage your lifestyle, you can lower, but not eliminate the risk of dementia.
Time to get exercised!
In summary, we should all get more exercised, as there’s a lot we can do to lower our risk of dementia or delay its onset and reduce the duration.
A lifestyle that includes a continuous learning, managing our heart health and staying socially connected can help build a cognitive and physical reserve to provide later life protection.
One call-out that is not yet fully understood, is exercise. This is free medicine that’s both preventative and curative, especially where the exercise includes resistance as well as aerobic training. Building skeletal muscle mass improves cognitive function and supports brain health.
Of course, even if we lower the risk of dementia, we cannot eliminate it. The genetic risk of dementia cannot be eliminated and those with one or two APOE-e4 genes have an even greater predisposition.
At Autum we believe that the path to improved longevity starts by measuring biological age. We use lifestyle for this, so we can also help the user navigate a pathway to improve lifestyle and wellness. If you have not yet done so, download our App via https://autum.life/ and tell us what you think.
Cover Photo by julien Tromeur on Unsplash
A passionate entrepreneur who has spent years calculating life risks and has set up two successful innovative businesses. He believes with the right motivation and support we can extend healthy life. This is now his calling and has found a great team to make it happen.
