Hello everyone and welcome to this week's blog post, which is the first in a two-part series about dementia. In this article, I hope to cover what dementia is and its causes. I will then conclude by summarising the latest research into curing Alzheimer's disease. For more about this research, make sure to read next week's article!
Dementia is a syndrome that describes various symptoms of cognitive decline, including impairment of thinking, memory, and ability to carry out tasks. While these changes of mental function start small, they often quickly become serious enough to interfere with a sufferer's ability to carry out daily tasks. Dementia is a serious problem in the UK and other developed countries, with around 850,000 people currently suffering from dementia in the UK alone. Indeed, this figure is predicted to rise to 1.6 million by 2040, clearly underlining the problem dementia poses for our ageing population.
Despite some popular belief, it is important to note however that while dementia mainly affects the older population, it is not an inherent condition that always accompanies ageing. As such, through better lifestyles and medical intervention, it is possible to at least reduce the impact dementia has on the elderly population.
Dementia is a syndrome, which means that it is not a disease itself, but simply describes a group of symptoms that are all associated with a decline of mental function. The term dementia, however, is often still used as an umbrella term to describe all diseases with these symptoms.
The most common type of dementia is Alzheimer's disease, which according to the Alzheimer's Society, affects 62% of those diagnosed with dementia. Alzheimer's disease is caused by the abnormal deposition of two key proteins (beta-amyloid and tau) in the brain. While both these proteins are present in healthy brain tissue, when they are abnormally deposited, they damage nerve cells. Abnormal beta-amyloid deposits outside neurons form plaques, collect between neurons and disrupt their function. Meanwhile, abnormal tau deposits inside neurons form tangles which block the neuron's transport system and hinders communication across the synapses. These deposits cause many neurons to lose their connections with others, stop functioning and die, thus leading to the shrinking of the brain (this is called brain atrophy) and eventually the onset of Alzheimer's disease.
Alzheimer's disease first impacts the hippocampus, which is the part of the brain responsible for the formation of memories. As such, sufferers from Alzheimer's often find it difficult to remember what just happened, such as what they were saying in a conversation.
Alzheimer's also results in the reduction of the presence of the neurotransmitter acetylcholine, which in turn decreases the amount that neurons can communicate with each other.
Despite the fact that there is no cure for Alzheimer's, there are many medicines which reduce its symptoms. The main group of these medicines are acetylcholinesterase inhibitors (such as donepezil) which work by inhibiting the enzyme responsible for metabolising acetylcholine. Because these enzymes can no longer break down acetylcholine, the concentration of the neurotransmitter remains higher for longer, allowing the neurons to communicate better with each other.
While the triggers of Alzheimer's are not known, we do know of many risk factors that increase the chance of developing the disease. The main risk factor is age: according to the Alzheimer's Society, after the age of 65, a person's risk of developing Alzheimer's doubles every 5 years.
Further, while you can sometimes inherit early-onset Alzheimer's from your parents, this is only the case in a very small number of families. For the most part, Alzheimer's can not be inherited from your parents. What can be inherited however are genes that both increase and reduce the risk of developing the disease. Additionally, people who suffer from Down's syndrome are also more likely to develop Alzheimer's, since the extra chromosome 21 results in an increase of beta-amyloid plaque formation in the brain.
The lifestyle that you lead also has a large impact on the risk of developing Alzheimer's later in life. Studies have shown that smoking, obesity, diabetes and high blood pressure and cholesterol all increase your chance of getting Alzheimer's. Consequently, one of the best ways to reduce the risk of developing the disease is to not smoke, exercise the mind and body regularly, and eating a healthy, balanced diet.
One of the rarer forms of dementia is caused by Huntington's disease. Huntington's disease is a progressive disorder of the brain that causes the deterioration of neurons in the brain. This then causes the symptoms of Huntington's disease, which include uncontrolled movement of the arms and legs, and a decline in thinking, loss of memory and reduction in an ability to plan and organise.
Unfortunately, the genetic defect on chromosome 4, which causes Huntington's disease, is 'dominant'. This means that if either parent has Huntington's disease, the child will also develop the disease later in life.
While there is no cure for Huntington's disease, or even any medication to slow the brain changes that the disease induces, medication can be used to reduce the symptoms and increase a sufferer's quality of life.
As I have explained above, we do not currently have a cure for dementia, however, there is a huge amount of research being done to try and develop new treatments. For example, there is lots of research being done into targeting beta-amyloid plaques formed by Alzheimer's. One of the main ways to do this, which is currently being trialled is the use of monoclonal antibodies. These are drugs which mimic the antibodies naturally produced by the immune system. By using these antibodies, scientists hope to be able to prevent plaques forming and decrease excess beta-amyloid in the brain. Furthermore, research is also being conducted into stopping the protein tau from forming tangles inside neurons.
I hope the article has helped you understand more about dementia. Next week, I will be exploring this research in-depth and discussing how much further we need to get for a cure. Subscribe to get notified when I publish the article!
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