Dementia and the Different Types
Introduction to Dementia
Although there are many different forms of dementia, Alzheimer's Disease, vascular dementia, Lewy body dementia, and frontotemporal dementia are the most common forms. These types of dementia usually result in an array of progressive symptoms and the inability to perform various tasks. However, there are rarer forms of dementia caused by other diseases and conditions. Some people can also develop multiple types of dementia, which is known as mixed dementia. Furthermore, it is possible for a younger person to develop dementia before the age of 65, known as young-onset dementia.
Common Types of Dementia
Alzheimer’s disease is a brain disorder that slowly destroys memory and thinking skills and, eventually, the ability to carry out the simplest skills and tasks (National Institute on Aging). Alzheimer’s disease is the most common cause of dementia among older adults, with the first symptoms appearing in their mid-60s. The initial damage affects parts of the brain involving memory and later affects areas responsible for language, reasoning, and social behaviour (National Institute on Aging).
Individuals with Alzheimer’s disease have trouble performing everyday tasks, such as driving a car, cooking a meal, or paying bills. They may also ask the same questions repeatedly, get lost easily, or lose things or put them in odd places. An individual expectancy with Alzheimer’s disease can be for as long as 10 or more years or as little as 3 or 4 years (National Institute on Aging).
Vascular dementia is the second most common type of dementia after Alzheimer’s disease. The most common symptoms of vascular dementia during the early stages are problems with planning, organizing, making decisions, or solving problems. People with vascular dementia often have difficulties following a series of steps, such as cooking a meal. Individuals also experience slower speed of thought, problems concentrating, and short periods of sudden confusion. Over time, symptoms may develop quickly and get worse, which can cause problems with everyday living.
There are three types of vascular dementia which all result from problems with blood supply to parts of the brain, causing localized brain damage: multi-infarct dementia, subcortical vascular dementia, and stroke-related dementia (Alzheimer’s Society).
Lewy body Dementia
Lewy body dementia (LBD) is a type of progressive dementia that leads to a decline in thinking, reasoning, and independent function.LBD is a broad term that includes both dementia with Lewy bodies and Parkinson’s disease dementia. Many individuals with Parkinson’s disease eventually develop problems with thinking and reasoning while those with DLB experience symptoms related to movement, such as hunched posture, rigid muscles, a shuffling walk, and trouble initiating movement. The overlap in symptoms and other evidence suggest that DLB and Parkinson’s disease may be linked to the same underlying abnormalities in how the brain processes the protein alpha-synuclein (Alzheimer’s Association).
Core symptoms of DLB include changes in thinking and reasoning, fluctuating cognition that is delirium-like, recurrent well-formed visual hallucinations, REM sleep behaviour disorder that involves acting out dreams, spontaneous parkinsonism with the slowness of movement, rest tremor, or rigidity (Alzheimer’s Association).
Frontotemporal degeneration (FTD) refers to a group of disorders caused by progressive nerve cell loss in the brain’s frontal lobes (the areas behind your forehead) or its temporal lobes (the regions behind your ears). There are different types of frontotemporal dementia (National Institute of Aging). In behavioural variant frontotemporal dementia, nerve cell loss is most prominent in areas that control conduct, judgement, empathy, and foresight, among other abilities (Alzheimer’s Association). Other forms of FTD, include primary progressive aphasia (PPA), which has similar symptoms that affect language, speaking, writing, and comprehension.
Although FTD is less common than Alzheimer’s disease in those over 65, it is much more common in individuals in their 40s and early 60s.
Since the many types of dementia have different causes, a person can have more than one type of dementia, referred to as mixed dementia. An individual living with mixed dementia will likely show symptoms of at least two different types of dementia, making it difficult to make an accurate diagnosis. The most common type of mixed dementia is Alzheimer’s disease and vascular dementia (Alzheimer’s Society).
Unfortunately, researchers are not exactly aware of how many people are currently diagnosed with mixed dementia. However, autopsy studies often indicate that mixed dementia may be much more common than previously realized (Alzheimer’s Society)
When you think of someone with dementia, the common image that comes to mind is often an elderly person in the later stages of the condition. However, it’s crucial to understand and recognize that dementia is not limited to older individuals. Despite age being the primary risk factor, this type of dementia can affect people in their 50s, 40s, and even as young as their 30s and 20s.
This form of dementia is referred to as “young-onset dementia,” comprising around 2 to 8% of all dementia cases (National Institute of Aging). The impact is significant, with at least 28,000 Canadians under the age of 65 currently living with young-onset dementia (Alzheimer’s Society). Symptoms include changes in behaviour, shifts in the ability to do everyday tasks, and difficulty in speaking or writing. Individuals also experience difficulty in seeing, controlling muscles, and balancing.
Many different factors change how an individual experiences young-onset dementia. Gender, sex, sexuality, job, income, language, and community can all affect and change their individual experience of living with this type of dementia.
Rare Types of Dementia
Atypical Alzheimer’s Disease
Although memory issues are the most common type of symptom of Alzheimer’s disease, 1 in 20 people with Alzheimer’s have different early symptoms (National Institute of Aging) This is called atypical Alzheimer’s disease. Even though this type of disease is caused by the same kind of changes in the brain as typical Alzheimer’s, these changes start in different parts of the brain and cause different symptoms.
There are two most common types of atypical Alzheimer’s disease are frontal variant Alzheimer’s disease (fvAD) and posterior cortical atrophy (PCA).
FvAD affects about 1 in 50 people who have Alzheimer’s disease (Alzheimer’s Society of Canada). This condition affects the frontal lobes of the brain during the earlier stages, something that wouldn’t happen until much later in typical cases. The damage to the frontal lobes can cause behavioural symptoms and problems with a type of thinking known as ‘executive function,’ meaning a person with fvAD is also likely to change personality and behaviour changes.
PCA is most often caused by the same changes in a person’s brain that cause Alzheimer’s disease. For PCA, it mainly affects the back of the brain in a region called the ‘visual cortex’ (National Institute of Aging). Symptoms in the early stages include difficulty recognising faces and objects in pictures and having issues with spatial awareness. Over time, these symptoms can develop into memory loss, confusion, and difficulties with communication.
CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) is a rare, inherited type of vascular disease that can cause dementia due to a faulty gene. A parent who carries the faulty gene has a 1 in 2 chance of passing CADASIL onto their child. Someone with CADASIL is likely to have a series of mild strokes that can cause damage to their brain tissue. CADASIL can have a range of symptoms that slowly develop over years, including issues with memory, thinking, and physical and emotional problems. In particular, it affects the person’s memory and the ability to work the things they see arranged in space (visuospatial skills).
Creutzfeldt-Jakob disease (CJD) is caused by an abnormally shaped protein infecting the brain. CJD affects about 1 in every million people each year. The most common type of CJD is sporadic CJD, which normally affects people who are over the age of 40. If someone is diagnosed with sporadic CJD, their symptoms will progress very rapidly, often within a few weeks or months. The very early symptoms consist of apathy, mood changes, and memory loss. However, these early signs will quickly transform into jerky movement, shakiness, stiff limbs, incontinence, and loss of the ability to move or speak.
Due to the rareness of this disease, there is currently no cure. However, it can be managed through medication and drugs such as clonazepam which specifically aims to improve stiff limbs and seizures.
Huntington’s disease (HD) is an inherited genetic condition that causes dementia. It causes a slow, progressive decline in a person’s movement, memory, thinking, and emotional state. In Canada, HD has an estimated disease prevalence of 4.0-13.9 individuals per 100,000 in the general population (Shaw et. al, 2022, pg. 2). People who are born with the gene that causes HD usually don’t show symptoms until mid-adulthood, around the ages of 30 to 50. If a parent has HD, their children will have a 50% chance of inheriting the gene (Shaw et. al, 2022, pg. 6).
In the early stages of HD, people are likely to develop symptoms of dementia, such as problems with their thinking and perception. Before their clear diagnosis, many people may be dealing with severe depression, apathy, irritability, and obsessive-compulsive behaviours. Specifically, the initial physical symptoms will gradually develop into more obvious involuntary movements such as jerking and twitching of the head, neck, arms, and legs. The later physical symptoms include difficulties walking, eating independently, and swallowing.
To conclude, dementia is a progressive neurological disorder with different symptoms that affect one’s cognitive abilities and memory significantly, interfering with their daily life. Understanding the unique features and causes of each type is crucial for accurate diagnosis and having the appropriate management of this dealing and living with this complex condition.