What Are The Different Types of Dementia?
This post is the first of many in a series about understanding the various types of dementia and how each one impacts an individual after diagnosis. We acknowledge that there are over 400 different types of dementia, we will be focusing on some of the more common ones as well as some of the not so common dementias that are affecting many people today. In this first post we will define dementia and briefly discuss each of the variations that are more common. Each subsequent post will explore a particular form of dementia.
According to the Center for Disease Control, dementia is not a specific disease but is rather a general term for the impaired ability to remember, think, or make decisions that interfere with doing everyday activities. Though dementia mostly affects older adults, it is not a part of normal aging.
Some of the more common types of dementia you have likely heard of are:
Alzheimer’s disease is the most common form of dementia. The disease includes a wide range of symptoms caused by neurodegeneration and the deterioration is progressive and symptoms worsen over time. The symptoms are irreversible because the damaged brain cannot be restored to normal. The cause of the disease is still unknown, but the two primary occurrences that characterize the disease are amyloid plaques and neurofibrillary tangles. Both occur because of a mass accumulation of a different protein. Some common symptoms of Alzheimer’s disease are:
- Increase in poor judgement and making decisions
- Confusion in the day or date combined with forgetting recent conversations or events
- Irritability, anxiousness, or depression because of their failure to manage tasks.
After receiving the diagnosis, you are expected to live between 4-8 years, but this number can vary depending on what staged you are diagnosed in.
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Vascular dementia also referred to as multi-infract or post-stroke dementia is a common form of dementia, but not as common as Alzheimer’s, however, it is the coexisting pathology with Alzheimer’s patients. Vascular dementia often exacerbates dementia symptoms and progression through combination. It includes a wide range of symptoms because of the neurodegeneration is caused by a reduction in the blood supply to the brain usually due to strokes. Some common symptoms of vascular dementia are:
- Slowness in thinking speed
- Problems concentrating, or
- Difficulty planning and organizing
The progression of vascular dementia can occur quick such as after a stroke, or more progressive due to small vessel disease. Life expectancy after symptoms begin is usually 5 years and the associated cause of passing is usually a stroke or heart failure.
Lewy Body Disease
This is a very complicated form of dementia that presents itself like Parkinson’s disease and Alzheimer’s disease. Dementia with Lewy Bodies includes a wide range of symptoms that are caused by neurodegeneration. It is a progressive deterioration of the brain that leads to worsening symptoms over time and provokes the appearance of new symptoms as it spreads in the brain. The main symptoms for Dementia with Lewy Bodies are:
- Memory Loss
- Visual hallucinations
- Sleep issues
The progression of dementia with Lewy bodies is gradual and the average survival time after a diagnosis is 6 years. Many symptoms can be compared to those of Alzheimer’s, but the symptoms listed above are unique to this form of dementia. At the later stages of the disease, it appears more and more like Alzheimer’s.
This is a term for a group of rare disorders affecting the frontal and temporal lobes of the brain. Frontotemporal dementia tends to occur at a younger age than other types of dementia. It includes a wide range of symptoms caused by neurodegeneration located in the frontal and temporal lobes. The degeneration is a progressive deterioration that leads to worsening symptoms over time and leads to new symptoms as it spreads in the brain.
The main functions that are affected are language skills, ability to focus, and the ability to control impulses. There are three types of frontotemporal dementia:
- Behavioral variant of frontotemporal dementia – this variation affects behavioral and executive functions first – thinking, planning organizing and problem solving.
- Progressive non-fluent aphasia – characterized in progressive deficit in speech and grammar and loss of comprehension of complex sentences.
- Semantic Dementia – progressive loss of semantic knowledge (word meaning), naming ability and word comprehension.
Each of these forms of dementia will be discussed at length in a later blog post.
The progression of these variations is all different. On average, those diagnosed with the behavioral variant of frontotemporal dementia, Progressive Non-fluent Aphasia, and Semantic Dementia live 6, 9 and 11 to 12 years respectively after diagnosis.
Other forms of dementia that will be discussed in this series are:
Young Onset Dementia
Unfortunately, dementia can affect adults of all ages. While age is a big risk factor when it comes to dementia, people in their 30s, 40s and 50s can also develop dementia. Young onset dementia accounts for an estimated 2 to 8% of all dementia cases. It is important to know that the term “young onset dementia” does not mean the early stages of dementia. A 54-year-old living with young onset dementia could already be in the late stages, while an 82-year-old that as just diagnosed with dementia might be in the early stages.
Signs of young-onset dementia can vary depending on what variation of dementia you are diagnosed with, but the first signs of young onset dementia can be similar to those of late-onset Alzheimer’s disease. Typical signs include:
- Personality changes, such as abruptness and insensitivity
- Frequent lapses of memory, particularly involving recent memories
- Forgetting appointments or the names of colleagues at work
- Mood swings, paranoia, and fearfulness.
- Losing interest in activities that were previously enjoyed.
There are other signs of early onset dementia that will be discussed in a later post dedicated to young onset dementia.
The mean survival time after symptom onset and diagnosis is between 10 and 17.5 years.
Different types of dementia can have different causes so, it is possible for a person to have more than one type of dementia and when this happens, a person has mixed dementia. Someone living with mixed dementia will show symptoms of at least two different types of dementia. This mix usually consists of the two most common types of dementia: Alzheimer’s disease and vascular dementia.
Symptoms of mixed dementia are not well defined because they can be a combination of symptoms that are common for multiple forms of dementia. The best way to determine what variations of dementia you have is to list your symptoms to a dementia specialist. Life expectancy after a diagnosis of mixed dementia is typically not long. This is due in part to 2 or more variations of dementia affecting different parts of the brain, ultimately accelerating the decline. The expected life expectancy of mixed dementia will be determined at the diagnosis.
This form of dementia was first reported on April 30, 2019 in a study that was published in Brain, a journal of neurology, identifying that a protein involved in your DNA, called TDP-43 that is the primary link to this new form of dementia. It has been named limbic-predominant age related TDP-43 encephalopathy or LATE-NC. Since this is such a newly discovered disease, we do not know too much about this form of dementia. When TDP-43 accumulates in an area located in the mid-brain known as the limbic system, it affects learning, memory, and emotion, resembling symptoms of Alzheimer’s disease. Researchers have stated that this disease is not currently diagnosable with standard tests. People are typically diagnosed based on symptoms they are experiencing and since the symptoms of this disease are very similar to that of Alzheimer’s, it would likely be misdiagnosed.
Rare Types of Dementia
There are numerous forms of rare types of dementia that include:
- Corticobasal syndrome
- Creutzfeldt-Jakob disease
- Huntington disease
- Multiple sclerosis
- Niemann-Pick disease type C
- Normal pressure hydrocephalus
- Parkinson’s disease
- Posterior cortical atrophy
- Progressive supranuclear palsy
- Wernicke-Korsakoff syndrome
More discussion on these rare types of dementia will follow in a later post.
Conditions Related to Dementia
The following conditions are related to dementia and can increase the risk of developing a form of dementia. More discussion one these conditions will follow in a later post.
- Down syndrome and Alzheimer’s disease
- Traumatic brain injury
- Mild cognitive impairment
Come back every month to find out more about different forms of dementia and the associated signs symptoms and stages of each form.