CAN WE PREVENT ALZHEIMER’S DISEASE?

Dementia ranks alongside cardiovascular disease and cancer as one of the most common causes of death in the UK. Fear of ageing can be driven in part due to worries over social isolation and physical illness but for many the thought of losing mental capacity can be particularly troubling. This post aims to discuss the most common cause of dementia and potential preventative measures in the form of lifestyle intervention.

WHAT EXACTLY IS ALZHEIMER’S?

Alzheimer’s is a disease that causes dementia and is the most common cause accounting for two thirds of cases. The disease is thought to be caused by the build-up of abnormal proteins in and around brain cells. Dementia is a syndrome associated with an ongoing decline in brain functioning. It is characterised by a loss of memory, language, thinking and problem-solving abilities which are severe enough to interfere with the activities of daily living. Alzheimer’s disease has shown a steady rise over the past decade as a cause of illness and death. This is likely due to a greater understanding of the illness and many more people receiving a diagnosis in an ageing population. The disease has a profound impact on the affected individual as well as their family.

The greatest risk factor for Alzheimer’s Disease is age. It must be stressed; however, this is not a direct cause, and the disease is not an inevitable consequence of ageing. Most patients suffering with Alzheimer’s however will be over the age of 65 years and after this age the risk of Alzheimer’s increases 2-fold every 5 years.

For us to answer the title question about prevention of dementia we must first consider the causes of Alzheimer’s Disease. We can divide these into the three following categories: Genetics, Lifestyle and Environment.

(Note, the increasing links between head trauma in sport and dementia has not been covered in this article)

GENETICS AND ALZHEIMER’S?

There are in fact several genes that exist that increase an individual’s likelihood of developing the disease, but this is not a guarantee that they will get the disease. The first risk gene identified for the condition is known as the APOE-e4 gene and remains the gene with the strongest impact. In those diagnosed with Alzheimer’s Disease 40-65% have the APOE-e4 gene. It is worth noting that we all have 2 forms (also known as ‘alleles’) of the APOE gene. There are at least 3 different versions of the APOE gene. The major alleles are known as e2, e3 and e4. It is specifically the e4 form which confer the highest risk.  If an individual has inherited two forms of the APOE-e4 gene, one from each parent, then there is a higher risk of developing Alzheimer’s Disease.

In addition to these genes there has also been the discovery of what are known as ‘deterministic’ genes. These are extremely rare but account for cases of early onset Alzheimer’s Disease. The presence of these genes will almost guarantee an individual will develop the condition and there is a higher chance it will happen much earlier in life. The discovery of these genes has aided our understanding of the disease process and will aid future research. These genes affect processing and production of a brain protein known as beta amyloid strongly implicated in Alzheimer’s. Abnormal levels of this naturally occurring protein can clump together and affect communication between cells and disrupt cell function in the brain eventually leading to cell death. Tau protein is a second protein which is implicated and can build up and damage brain cells. They are naturally occurring but for a reason not fully understood, in Alzheimer’s disease they are susceptible to clumping together and forming ‘tangles’ which can affect the nerve cell transport system and lead to brain cell death.

So, should I get genetic testing?

This is not currently recommended. With no well-established widely available

effective treatments for prevention or curing Alzheimer’s this would only serve to increase anxiety levels unnecessarily. Medications do exist to slow decline in loss of function, but these also have limitations.

LIFESTYLE:

The risk of Alzheimer’s dementia and vascular dementia (the second most common cause of dementia) are increased by medical conditions that can have an impact on blood vessels and the heart. Those patients with type 2 diabetes, high blood pressure, cardiovascular disease and stroke are typically more predisposed. Research has shown healthy ageing is important in reducing risk. Focusing on the 6 key pillars of health including diet, physical activity, stopping tobacco and reducing excess alcohol, keeping socially active, sleeping 7-9 hours at night, and controlling stress, has great potential to reduce Alzheimer’s risk.

DIET

From a dietary point of view there has been research to illustrate better outcomes in patients and reduced progression in existing Alzheimer’s patients in those adopting the following dietary measures:

  • A Mediterranean diet or a whole food plant-based diet
  • Incorporating vitamin E into one’s diet specifically from food (vitamin E-rich foods include almonds, sunflower seeds, peanuts, avocados, spinach, butternut squash and fish such as salmon or trout) rather than supplements.
  • Taking food rich in DHA (docosahexaenoic acid). This is a particular type of Omega 3 Fatty Acid and can be found in oily fish such as mackerel, salmon and trout. Supplements are also available including in vegan form (derived from algae).
  • Taking food or supplements rich in vitamin B12 (dairy and meat) and folic acid (wholegrains)
  •  Incorporating extra virgin olive oil into the diet
  •  Taking a vitamin D3 supplement regularly
  •  If taking a multivitamin supplement for dementia it has also been purported that one without copper and iron is best.

AEROBIC EXERCISE:

Whilst it has been postulated that physical activity is good for the brain, studies have shown that it is specifically aerobic exercise (rather than high intensity exercise or weight training) which is most effective in dementia prevention and progression. New research shows that it may reduce shrinkage of the hippocampus, the part of the brain that deals with memory. It has been speculated that aerobic exercise may be unique in that it increases the blood supply to the brain as well, encouraging growth and survival of nerve cells, as well as mitigating against the effect of harmful amyloid plaque on the memory centre of the brain.

SLEEP:

We are seeing an increasing link between Alzheimer’s Disease and poor sleep which is thought to be more than just an association. Sleep for Alzheimer’s sufferers is a real issue. It is worth noting that disruption of deep sleep precedes the onset of Alzheimer’s disease suggesting that it may be an early warning sign. However, it is yet unclear as to whether poor sleep increases the risk of Alzheimer’s disease (by reducing the clearance of beta amyloid protein from the brain) or whether the disease itself has a direct effect on the areas of the brain responsible for deep sleep. Both in fact may be true and have a spiralling negative effect on one another.

At this stage, the relationship of specific diets, telomere length (the protective DNA caps at the end of chromosomes), the gut microbiome, chronic inflammation in the body and epigenetics (changes in gene expression) are all being studied to provide a greater insight into the mechanisms by which lifestyle changes can affect Alzheimer’s Disease.

WHAT ABOUT THE ENVIRONMENT?

There is increasing evidence that brain cell degeneration can occur because of chronic low-level exposure to pesticides, air pollution, industrial pollutants, and potentially certain environmental metals. Long term accumulation of these products within our bodies are speculated to lead to inflammation within the brain paving the way for conditions which allow Alzheimer’s to develop. We are still unsure, however, how these environmental pollutants interact with our own genetics to lead to an increased risk of Alzheimer’s dementia. Suffice to say an improvement in our own environment may reduce risk of dementia.

When considering environment, it is important not to only consider the natural environment, but we must consider an individual’s social environment. Low socioeconomic status has the potential to lead to poor nutrition, increasing stress as well as increased social isolation which will all increase the risk of Alzheimer’s Disease.

Vitamin D deficiency has also been shown to have an association with Alzheimer’s disease amongst a whole host of other medical conditions. Sunlight exposure is the natural source of vitamin D. Though it can vary depending on how an individual metabolises vitamin D, a general recommendation for adult patients is to supplement with 20-25 micrograms of vitamin D daily during the winter months and all year-round if from an ethnic minority background or if at risk from inadequate sunlight. Please speak to your doctor for further guidance.

MEDICATIONS FOR ALZHEIMER’S DISEASE

There are several different medications which have been used in Alzheimer’s disease. It is worth noting that no medication can stop the damage the disease does to brain cells, but the aim is to slow the progression of symptoms. These symptoms relate to memory, thinking, language, judgement, and other thought processes. The most used medication in the NHS for Alzheimer’s Disease is Donepezil. This is because it is approved for use at all stages of the disease. It can hinder worsening of symptoms by preventing the breakdown of a nerve cell chemical messenger known as acetylcholine which is important for learning and memory. An alternative medication known as Memantine is approved for moderate to severe dementia. It works in a different way by regulating the activity of a chemical called glutamate, which is involved in information processing and retrieval. This drug can improve the ability to perform daily activities in some.

These medications certainly have limitations, however. They tend to be helpful for a limited time only and can have varied side effects. Further research trials are being done to find better medications than the ones which currently exist. These are urgently needed with the forecasted rise in Alzheimer’s cases. The first new treatment for Alzheimer’s disease for 20 years was approved by the US in June 2021. This medication is known as Aducanumab and is given as a monthly intravenous infusion. Aducanumab is thought to work by reducing beta amyloid plaques in the brain. This news has been greeted with cautious optimism by neuroscientists, however, as it may only confer benefits in a selected few.

Unlike with heart disease, type 2 diabetes, and high blood pressure it can be far more difficult in research studies to show comprehensively that lifestyle interventions can significantly improve outcomes in dementia. These types of studies are far harder to design and would need ongoing education, counselling, and support over a longer period to show meaningful change. Pharmaceuticals are deeply embedded within western medical society and money for research is far more likely to be ploughed into the development of drugs. Nevertheless, the current science strongly indicates lifestyle interventions can reduce risk and the disease processes in Alzheimer’s disease can occur a good 30 years prior to symptom onset so early lifestyle intervention is advised.

SUMMARY

  • Dementia is amongst the top two of most feared diseases in the developed world (the other being Cancer) due to the gradual decline in mental capacity. It is one of the leading causes of death in the UK.
  • The causes of Alzheimer’s disease are related to genetics, lifestyle and the environment.
  • Though medications exist for Alzheimer’s they cannot stop the damage the disease does to brain and nerve cells and the communication network that exists between them. At best medications can reduce progression of symptoms.
  • The role of lifestyle is well established in Alzheimer’s Disease. Our genetics will no doubt have a role, but prevention by adopting the six key pillars of health including a minimally processed plant-based diet, physical activity, smoking cessation, stress reduction, adequate sleep and social activity will only serve to benefit.
  • As the disease process occurs many years before symptom onset we should try and intervene early with lifestyle measures. This will increase longevity and health span, which will mitigate against the risk factor of ageing.

References

www.alz.org

www.alzheimers.org.uk

A 2-year multidomain intervention of diet, exercise, cognitive training, and vascular risk monitoring versus control to prevent cognitive decline in at-risk elderly people (FINGER): a randomised controlled trial.  Ngandu T, Lehtisalo J, Solomon A, Kivipelto M et al. Lancet. 2015

Healthy lifestyle and the risk of Alzheimer dementia: Findings from 2 longitudinal studies. Dhana K, Evans DA, Rajan KB, Bennett DA, Morris MC. Neurology. 2020 Jul

World Health Organisation: Risk reduction of cognitive decline and dementia, 2019 Guidelines

Cognitive leisure activities and future risk of cognitive impairment and dementia: systematic review and meta-analysis. Yates LA, Ziser S, Spector A, Orrell M. Int Psychogeriatr. 2016