Newsletter Shorts: Dementia and Alzheimer's
Over the past few weeks, the regular newsletter has focused on neurological diseases, and how exercise can aid those living with PD and MS. Today’s edition is a short outline on dementia, specifically, Alzheimer’s disease: common symptoms, outlook and progression, and how exercise and lifestyle may be able to mediate the risk of developing dementia as we age.
Dementia
Dementia is a general umbrella term which best describes a series of symptoms related to cognitive decline. This may include worsening memory, difficulties with thinking, problem-solving, and language, changes in mood or behaviour, and difficulty performing everyday tasks. It tends to be more common in those aged 65 or over, but can occur at any age. In the UK, estimates suggest that ~1 million individuals are currently living with a form of dementia, with this due to increase over the next five years.
There are many different types of dementia. If you have previously read the article on PD, you’ll be aware that dementia is a part of the Parkinson’s disease process. Other common types of dementia include:
Alzheimer’s disease (60-70%)
Vascular dementia (10-20%)
Frontotemporal dementia (~10%)
Lewy body dementia (~5%)
It is also possible for mixed dementia to occur, where changes in the brain, associated with more than one type of dementia, take place simultaneously.
Alzheimer’s Disease
We have already established that Alzheimer’s disease is the most common sub-type of dementia, but let’s take a look at the specific symptoms and etiology.
Those with the disease tend to progressively decline in cognitive function. They may have trouble with memory, concentration, recognising familiar people or objects, and are often confused or disorientated, which may present in the form of slow or slurred speech. This disease will typically strip the individual of their independence, as they will frequently be unable to perform necessary daily tasks by themselves. By the time Alzheimer’s is advanced, the individual may develop hallucinations, struggle to swallow when eating and drinking, and also develop incontinence.
Causes
Alzheimer’s disease occurs when neurones in the brain become abnormally covered in amyloid protein plaques. This build-up affects the communication between the cells, which causes the immune system to activate a series of responses which then lead to inflammation, worsening the matter and further damaging the neurones. Another type of protein, called tau, may also accumulate within the brain cells. These tau deposits then get tangled, which affects the ability of the cells to function properly and survive. A downstream effect of these changes is a decrease in neurotransmitter concentration. In particular, Acetylcholine appears to be consistently lower in concentration in those with Alzheimer’s disease relative to healthy populations.
These changes eventually lead to a shrinking in certain areas of the brain. Typically, the first area which is affected is the part of the brain responsible for memory, which is why memory loss is a key aspect of the disease. However, it is widely agreed that these processes take place years in advance of the first signs and symptoms appear.
A genetic component?
There may be a genetic component to the development of Alzheimer’s disease. The Apolipoprotein E gene (APOE) is now well researched in this field and it is thought that those with certain alleles (ε) may be at increased or decreased risk. For example:
APOE ε2 may be protective –e.g. - If someone with this allele (up to 10% of the population) develops Alzheimer’s, it will likely be later in life.
APOE ε3, which is the most common allele, neither increases nor decreases the risk of Alzheimer's.
APOE ε4 (15-25% of the population) is associated with increased risk of earlier-onset Alzheimer’s.
Of course, we inherit two alleles of the gene from our parents, so there are 6 combinations in total. A ε4/ ε4 combination represents up to 5% of the population, and is, theoretically, the highest risk combination of alleles, but it must be stressed that people with two copies of this allele may still never develop Alzheimer’s.
Lifestyle
There a good body of research which suggests that lifestyle choices that increase the risk of cardiovascular disease may also present an increased risk of developing Alzheimer’s. As such, common co-morbidities include: obesity, diabetes, hypertension, and hypercholesterolaemia.
Therefore, it would make sense to reduce the risk of developing these lifestyle diseases by:
Getting enough exercise – 150 minutes of moderate activity each week, and 2x resistance training sessions per week. Limit sedentary time.*
Stopping smoking
Eating a balanced diet
Losing excess fat if necessary/applicable
Reducing alcohol intake if over the recommended weekly intake.
*According to the Alzheimer’s Society, regular exercise not only reduced the risk of Alzheimer’s by 45%, but also dementia of all kinds by just under 30%. One study even suggested that the 10% least active individuals are more than twice as likely to develop Alzheimer’s than the 10% most active individuals.
So, it sounds as though exercise may be the biggest lifestyle factor for managing risk, right? Well, there is one more factor which may be an even bigger determinant...
Social isolation
Loneliness in the elderly may increase the risk of developing dementia by up to 60%. There is no clear answer as to why this may be the case, but theories suggest that a lack of social contact may mean that individuals are likely to drink more alcohol, smoke more, exercise less, and eat more unhealthily than those with consistent friend or family support systems, and a sense of community. It is also important to consider that retirement from work takes away a regular social connection and sense of purpose. It may not be a surprise that Alzheimer’s is more common in over 65’s - an age historically associated with retirement and pension. Alzheimer’s support groups are therefore vital for getting people re-engaging with a community, and many will often meet up weekly for a sing-song, to engage in activities together, and create bonds with local people.
That’s all for today – a short newsletter available to everyone, no subscription required. If you’d like to learn more about this topic, head over to the Alzheimer’s Society or NHS Page for further information and help. Thanks, and see you next week!