Understanding the most common types of dementia

There are a number of types of dementia. The overlap in symptoms of various dementias can make it hard to get an accurate diagnosis for a particular type. A health care professional will be required to make a proper clinical diagnosis, and this will become the basis for interventions and important treatment decisions. The following information is provided to give you an overview of the different types of dementia as many people are familiar with just the one type, Alzheimer’s disease.

What is dementia?

Dementia is an overall term used to describe a set of signs and symptoms your parent may be experiencing and/or that you are observing in them.  Symptoms may include memory loss and difficulties with thinking, problem-solving, language skills, visual perception, self-management, the ability to focus and pay attention. A person with dementia may also show changes in mood, personality and behaviour. These signs and symptoms are caused by disorders which affect the brain and are usually severe enough to interfere with a person’s daily life, activities and relationships.

What causes the signs and symptoms of dementia?

Symptoms of dementia are sometimes caused by conditions that are treatable, such as depression, thyroid disease, infections, or drug interactions. If the symptoms are not treatable and progress over time, the cause could be a neurodegenerative disease. These diseases are progressive ,with irreversible loss of brain cells and decline of the person’s function over time. Currently there are no cures for these diseases.

 Alzheimer’s disease is the most common cause of dementia. Other degenerative diseases include frontotemporal disorders, Lewy body dementia, and vascular dementia. It is common for people to have mixed dementia—a combination of two or more types of dementia. For example, some people have both Alzheimer’s disease and vascular dementia.

Alzheimer’s Disease

Alzheimer’s disease (AD) is the most prevalent form of dementia and may contribute for 60% to 70% of all dementia cases. Dr. Alois Alzheimer first identified the disease in 1906. He described the two hallmarks of the disease. “Plaques” which are numerous tiny, dense deposits scattered throughout the brain that become toxic to brain cells at excessive levels, and “tangles,” which interfere with vital processes, eventually choking off the living cells. When brain cells degenerate and die, the brain shrinks.

Forms of Alzheimer’s disease

The most common form of Alzheimer’s disease is called sporadic Alzheimer’s disease; it has no specific family link. Sporadic Alzheimer’s disease is due to a complex combination of our genes, our environment and our lifestyle. Sporadic Alzheimer’s disease usually does not run in families. Age is the greatest risk factor for developing sporadic Alzheimer’s disease. Most sporadic Alzheimer’s disease begins after age 60-65.

Familial Alzheimer’s disease (FAD) is a rare form of Alzheimer’s disease with very strong family histories of Alzheimer’s disease affecting many family members over many generations. Familial Alzheimer’s disease runs in families and accounts for less than 5% of all cases.

 Alzheimer’s treatment

Several medications are available that can help with symptoms such as decline in memory, language, thinking abilities and motor skills. People who respond to medication can experience improvements in their quality of life that may last months or several years. However, medications can affect people differently and not everyone will respond to these treatments.

Frontotemporal Dementia

Other names often used for frontotemporal dementia: Pick’s Disease, Semantic Dementia, Frontal Lobe Dementia, Primary Progressive Aphasia, Corticobasal Degeneration, Behaviour Variant Frontotemporal Dementia)

Frontotemporal dementia (FTD) is an umbrella term for a group of uncommon disorders that primarily affect the frontal and temporal lobes of the brain – the areas generally associated with personality and behaviour. Researchers estimate that approximately 2-5% of all dementia cases are FTD. Frontotemporal dementia tends to occur at a younger age than Alzheimer’s disease and can affect both men and women. The average length of the disease is 2-10 years.

Early symptoms often affect either behaviour and/or speech (language). Changes in behaviour may include a progressive decline in socially appropriate behaviour, judgement, self-control, and empathy. The person can become either withdrawn or disinhibited (e.g. losing the ability to restrain one’s behaviour and actions). They may lose interest in personal hygiene, become easily distracted or repeat the same action over again. Compulsive behaviours may occur like spending, overeating, excessive drinking. Prominent changes in personality may also occur.

Problems with speech (language) can range from speaking less to total loss of speech, i.e. becoming mute. They may have difficulty finding the right words and may talk around the words or describe what they mean. Echoing what has been said by others and stuttering are common symptoms. The person may have difficulty sustaining a train of thought or maintaining a conversation for any length of time. Writing and reading are also affected. Unlike AD, a person with FTD often remains oriented to time and has preserved memory in the early stages.  In the later stages of the disease, general symptoms of dementia arise.

At present there is no known cure and no effective way to slow the progression. Treatments used in Alzheimer’s disease do not usually work for the treatment of Frontotemporal dementia as different areas of the brain are affected. There are medications that can reduce agitation, irritability and/or depression. These treatments should be used to help improve quality of life.

Lewy Body Dementia

Other names for LBD include diffuse Lewy body disease, Lewy body disease, Lewy body dementia and Lewy body variant of Alzheimer’s disease)

Lewy body dementia (LBD) is a form Lewy body dementia is a form of dementia that occurs because of abnormal deposits of a protein called alpha-synuclein inside the brain’s nerve cells. These deposits are called “Lewy bodies,” after the scientist who first described them. The deposits interrupt the brain’s messages. Lewy body dementia usually affects the areas of the brain that involve thinking and movement. Why or how Lewy bodies form is unknown. Lewy body dementia can occur by itself, or together with Alzheimer’s disease or Parkinson’s. It accounts for 5-15% of all dementias.

A person with Lewy body dementia may have symptoms much like those of both Parkinson’s disease and Alzheimer’s disease. Lewy body dementia usually progresses quickly. Problems with memory may not be an early symptom but can come up as Lewy body dementia progresses. Visual hallucinations (seeing things that are not real) are common and can be worse during times of increased confusion. The visual hallucinations often come back again and again, and typically are of people, children or animals. Some features of Lewy body dementia can resemble those in Parkinson’s disease. These include rigidity (stiffness of muscles), tremors (shaking), stooped posture, and slow, shuffling movements. Sensitivity to medication, especially some sedatives, may make these symptoms worse.

Treatment is often individualized, focusing on the symptoms in order of severity to avoid overmedication. Doctors may prescribe medications to treat symptoms such as those associated with Parkinson’s disease, depression, and unpleasant hallucinations.

Vascular Dementia

Vascular dementia  (VaD) is widely considered the second most common cause of dementia after Alzheimer’s disease. VaD occurs when the brain’s blood supply is blocked or damaged, causing brain cells to be deprived of oxygen and die.

How does that happen? A network of blood vessels called the vascular system supplies the brain with oxygen, allowing the brain to function properly. If the vessels supplying the brain are blocked, diseased or bleeding, blood is prevented from reaching the brain. With no oxygen and nutrients, the affected cells in the brain die. This can lead to stroke symptoms that may cause vascular dementia. Stroke symptoms may include paralysis and loss of speech. Someone with vascular dementia may notice changes in their ability to make decisions, plan, or organize as their first symptoms. Other changes may include difficulties with movement, such as slow gait and poor balance.

Symptoms tend to appear slowly, and specific impairments may occur in steps, where the person’s abilities can deteriorate, stabilize for a time and then decline again. Identifying the risk factors for VaD is important because often they may be treated to reduce the risk of stroke.

When Alzheimer’s disease and vascular dementia occur at the same time the condition is called mixed dementia.

Remember, If dementia is suspected, a number of physical and cognitive tests will most likely be performed to determine the cause of the dementia symptoms. A combination of physical and cognitive test results, along with a detailed medical history will help provide your health practitioner with the evidence needed to make an accurate diagnosis for your parent.