Dementia is a group of diseases that affects memory, thinking and social abilities. To the extent where it impacts the daily life of the patient. Symptoms of dementia include memory loss, behavior changes (such as being more aggressive) and personality changes such as depression. The most common disease relating to dementia is Alzheimer’s. However, there are more than 50 conditions that can be classified under dementia. These conditions include mixed dementia which is also very common. This is when different conditions of dementia mix together such as Alzheimer's and vascular dementia. In this research paper, I will discuss the various types of dementia in depth and discuss the future of dementia.
Dementia is a disease that affects over 55 million people worldwide (2020) with a new patient developing it every three seconds. It is expected that there will be 139 million people living with dementia in 2050. Not only that, it is expected that the total cost of dementia will reach up to US$2.8 trillion by 2030.
Memories are the part of the body that are greatly affected by dementia. To understand what dementia does to the body, we need to know how memories are formed. Memories are formed when the neurons in our brain interact and form connections with each other. New connections are created every time a person learns a new activity and the formation of these connections are called synapses. The more the person exercises that activity, the stronger the synapses become which is why practicing is crucial if we want to do better in that activity.
Alzheimer's is by far the most common type of dementia accounting for 60%-70% of all dementia patients. Alzheimer's is caused by the build-up of two proteins, amyloid and tau. The build-up of amyloid is called plaques. These plaques surround and exert pressure on the brain cells, neurons. While the deposits of tau tangle with the neurons. Both of these conditions can lead to the eventual death of the neurons which means that these neurons are unable to establish new connections or maintain their conditions leading to memory loss and not being able to remember new things.
These two proteins are toxic when in high components. Therefore, they activate the immune cells in the brain called microglia which usually clear toxic proteins. With the increase of the toxic proteins (amyloid and tau) in people with Alzheimer's, more microglia will be secreted and this will cause inflammation. Brain function will be compromised because of this and because of this inflammation, the brain cannot metabolize glucose as efficiently leading to its cells' death as they do not receive enough nutrients.
Alzheimer’s usually appears by itself with age, but genetics also play a role. For example, people with the APOE-e4 gene are more likely to develop Alzheimer's than people who do not have the APOE-e4 gene. The APOE gene is the main molecule that transports cholesterol in the bloodstream. There are three alleles of it: e2, e3, and e4. People with the e4 allele are more likely to develop Alzheimer's as they are more likely to have beta-amyloid accumulations.
Besides the abnormal build-up of proteins, the neurotransmitters (chemical messengers) in people with Alzheimer's are affected. The neurotransmitters are said to decrease and this also alters one’s ability to remember things clearly. The most popular of these neurotransmitters is acetylcholine. Therefore, to treat this, doctors would sometimes prescribe people with Alzheimer’s donepezil to increase levels of acetylcholine to improve brain functions and symptoms.
Currently, there are no known drugs to cure Alzheimer's. However, positron emission tomography can detect if there are abnormal levels of beta-amyloid or tau for early detection. To treat Alzheimer's, there is donepezil, rivastigmine, and galantamine. They increase the number of chemicals and increase the activity of neurotransmitters. There is also memantine which protects the neurons from overstimulation. Additionally, Aducanumab is also a drug used to treat Alzheimer's and is the first drug to address the cause of the disease by reducing the amyloid plaques in the brain, but there are still risks with the treatments. Therefore research on how to treat Alzeimeher’s is till being done now.
Younger onset Alzheimer’s
This version of Alzheimer's affects people in their 40s and 50s, unlike Alzheimer's which usually affects people in their 60s above. They are inherited and caused by mutations in the APP, PSEN1 and PSEN2 genes. The APP gene makes the amyloid precursor protein which typically regulates cellular functions, helps cells to bind to one another and directs the movements of neurons. Whilst the PSEN1 makes the protein presenilin 1 which is used to cut other proteins into small pieces. Lastly, PSEN2 makes protein present in 2 which helps transmit chemical signals from the cell membranes into the nucleus. The mutations in these genes cause the build-up of toxic deposits which kills the neurons and eventually brain tissues.
Another condition classified under dementia besides Alzheimer's is Vascular dementia. This type of dementia amounts to between 10-20% of all dementia cases. This type of dementia are not caused abnormal proteins so is very different from other types of dementia such as Alzheimer's. But they are caused by atherosclerosis which is the build-up of fat and cholesterol and/or arteriosclerosis which is the hardening and loss of elasticity in the artery walls. They are also caused by strokes which narrow or block the arteries to the brain. This causes the blood supply to the brain to be cut off and the brain will not be able to receive oxygen to function normally so many of the neurons and other brain cells die.
Therefore, this usually affects one ability to reason, plan, judge and remember. Vascular dementia often affects the speed of thinking and problem-solving ability rather than memory loss, unlike Alzheimer’s. Furthermore, people who have dementia and have a stroke (vascular dementia) only survive on average for 3 years. This is because there are currently no FDA-approved drugs for this condition; there is currently no way to reverse any loss of brain cells.
There are different types of vascular dementia. Multi-infarct dementia is vascular dementia caused by smaller strokes or transient ischemic attacks (TIA). The symptoms of the strokes are typically temporary. But it can cause permanent damage to the brain; these infected areas are called infarcts. If a person has a lot of mini-strokes. Then multiple infarcts may build up in the brain causing dementia.
This is the last of the major conditions under dementia. Frontotemporal dementia responsible for 10% of all dementia cases. It is caused by the abnormal clumping of proteins of tau and TDP43 in the frontal and/or temporal lobes (front and sides of the brains). This can damage the nerve cells leading to death. This causes the brain to shrink in those areas which is called atrophy. Frontotemporal dementia usually affects 45-65 year old's when other types of dementia usually affect people over the age of 65 year old's and causes problems mainly with behavior and language. There are also physical effects of frontotemporal dementia. For example, slow and stiff movements, loss of bladder and/or bowel control, muscle weakness and difficulty swallowing.
Like with other types of dementia, frontotemporal dementia also has many types. The first one is behavioral variant frontotemporal dementia and this causes damage to the frontal lobes. Therefore, the consequences of this type of frontotemporal dementia is that it will cause concerns with behavior and personality as these lobes control how we behave and our ability to control our emotions. It also decreases our ability to plan, solve problems, focus and finish our tasks. Many people with behavioral variant FTD are not aware of their symptoms. These symptoms include losing motivation at things they used to enjoy, struggling to focus on tasks and getting distracted easily, finding it difficult to plan/organize/make decisions (which is usually first noticed at work or when managing money), behaving impulsively and inappropriately (such as making rude comments), not being able to understand what others are thinking (for example: being less friendly, inconsiderate or losing interest in social activities), craving sweet and fatty foods and carbs and forgetting table manners (such as not knowing when to stop eating or drinking).
The other type of frontotemporal dementia is primary progressive aphasia (PPA). This type of frontotemporal dementia damages the temporal lobes which cause language problems. This is because the temporal lobe stores the meanings of words and the names of objects. If the right temporal lobe is affected, then the patient will also start to not be able to recognize familiar objects and faces. There are two types of PPA. The semantic variant is when patients lose their vocabulary over time. They initially forget technical words rather than basic words but eventually forget what familiar objects are used for (e.g : they might forget what a toaster does and why it is in the kitchen). They may also be obsessed with daily routines and often have eating difficulties and can lose the ability to use everyday objects such as cutlery/toothbrushes. The other type is the non-fluent variant PPA. This causes issues with speaking. For example, patients start to speak at a different speed and use wrong grammar or speak in the wrong word order. They might also use shorter and simpler sentences and say the opposite of what they mean. However, they can still understand individual words unlike people with the semantic variant. But over time, they struggle to understand full sentences.
Frontotemporal dementia also can affect how sensitive a person can be to things like temperatures, sounds, and pain. People with frontotemporal dementia also often develop other diseases. For example, motor neuron disease which causes muscles to weaken and waste away which in turn can cause paralysis. Patients are also likely to develop corticobasal syndrome and progressive supranuclear palsy which also weakens muscles, therefore causing movement difficulties such as muscle twitching and stiffness, slow and slurred speech, and loss of balance.
Future of dementia
A study showed that dementia in the US decreased by 13% per decade between 1988 and 2015. If this trend continues, then we can expect to have fewer dementia patients in the future. This is because people are now more aware of exercise habits and eating healthy as these factors all influence the likelihood of getting dementia. However, there will still always be people with dementia.
Therefore, the Alzheimer's Society which is a task force composed of researchers, research funding agencies, clinicians etc are working together to reduce the effects of dementia on patients and their families. One of the goals is to prevent future cases of dementia through increasing knowledge of risk and protective factors through further research. They want to understand and identify the risk of dementia and how to protect people from dementia. One of the ways that they plan to do this by using genetics to get groups with similar profiles to prevent the risk as people with some genes are more inclined to develop dementia than those who do not have those genes
Their second goal is to maximize the benefits to people living with dementia and their families to receive a diagnosis of dementia by researching and giving out surveys. A third goal is to improve the quality of life for people affected by dementia. This can be done by evaluating and developing treatments for illnesses caused by dementia such as depression and by educating the community on how to interact with dementia patients. Improving job performance and job satisfaction of workers helping dementia patients is another goal. The Alzheimer's society also plans to attract and retain more people in this industry to deliver improved care by increasing knowledge.
Closing off, it will be almost impossible to live in a world where dementia is non-existent. If there is, it would definitely take a long time. However, science advances day by day and one day there will be a cure for dementia. A day when dementia patients and the people around them do not need to suffer. But as of now, it is really important to take care of and understand dementia patients, not forgetting to support the people closest to them as well.