THE DIFFERENT TYPES OF DEMENTIA
The following is a summary of information to help you better understand dementia. If you or a loved one is experiencing memory difficulties or other changes in thinking skills, don’t ignore them, see a professional soon to determine the cause. Even though there is no known cure, early diagnosis allows a person to get the maximum benefit from available treatments.
WHAT IS DEMENTIA? Dementia is not a specific disease but an overall term that describes a wide range of symptoms associated with a decline in memory or other thinking skills severe enough to reduce a person’s ability to perform everyday activities. While symptoms of dementia can vary greatly, at least two of the following core mental functions must be significantly impaired to be considered dementia: memory, communication and language, ability to focus and pay attention, reasoning and judgment, or visual perception.
Alzheimer’s disease is the most common form of dementia and accounts for 50 to 80 percent of dementia cases. Alzheimer’s is a type of dementia that causes problems with memory, thinking and behavior. Alzheimer’s is not a normal part of aging, although the
greatest known risk factor is increasing age, and the majority of people with Alzheimer’s are 65 and older. But Alzheimer’s is not just a disease of old age. Up to 5 percent of people with the disease have early onset Alzheimer’s (also known as younger-onset), which often appears when someone is in their 40s or 50s. Alzheimer’s worsens over time. Alzheimer’s is a progressive disease, where dementia symptoms gradually worsen over a number of years. In its early stages, memory loss is mild, but with late-stage Alzheimer’s, individuals lose the ability to carry on a conversation and respond to their environment. Alzheimer’s is the sixth leading cause of death in the United States. Those with Alzheimer’s live an average of eight years after their symptoms become noticeable to others, but survival can range from four to 20 years, depending on age and other health conditions.
Symptoms: Difficulty remembering names and recent events is often an early clinical symptom; apathy and depression are also often early symptoms. Later symptoms include impaired judgment, disorientation, confusion, behavior changes and difficulty speaking, swallowing and walking.
Vascular dementia is widely considered the second most common cause of dementia after Alzheimer’s disease, accounting for 20 to 30 percent of cases. Vascular dementia is a decline in thinking skills caused by conditions that block or reduce blood flow to the brain, depriving brain cells of vital oxygen and nutrients. In vascular dementia, changes in thinking skills sometimes occur suddenly following strokes that block major brain blood vessels. Thinking problems also may begin as mild changes that worsen gradually as a result of multiple minor strokes or other conditions that affect smaller blood vessels, leading to cumulative damage. A growing number of experts prefer the term “vascular cognitive impairment (VCI)” to “vascular dementia” because they feel it better expresses the concept that vascular thinking changes can range from mild to severe. Vascular brain changes often coexist with changes linked to other types of dementia, including Alzheimer’s and dementia with Lewy bodies.
Symptoms: Impaired judgment or ability to plan steps needed to complete a task is more likely to be the initial symptom, as opposed to the
memory loss often associated with the initial symptoms of Alzheimer’s. Occurs because of brain injuries such as microscopic bleeding and blood vessel blockage. The location of the brain injury determines how the individual’s thinking and physical functioning are affected.
Dementia with Lewy bodies is the third most common and accounts for 10 to 25 percent of cases. Dementia with Lewy bodies (DLB) is a type of progressive dementia that leads to a decline in thinking, reasoning and independent function because of abnormal microscopic deposits that damage brain cells over time. The hallmark brain abnormalities linked to DLB are named after Frederick H. Lewy, M.D., the neurologist who discovered them while working in Dr. Alois. Alzheimer’s laboratory during the early 1900s. Alpha-synuclein protein, the
chief component of Lewy bodies, is found widely in the brain, but its normal function isn’t yet known. Lewy bodies are also found in other brain disorders, including Alzheimer’s disease and Parkinson’s disease dementia. Many people with Parkinson’s eventually develop problems with thinking and reasoning, and many people with DLB experience movement symptoms, such as hunched posture, rigid
muscles, a shuffling walk and trouble initiating movement. This overlap in symptoms and other evidence suggest that DLB, Parkinson’s
disease and Parkinson’s disease dementia may be linked to the same underlying abnormalities in how the brain processes the protein alpha-synuclein.
Symptoms: People with dementia with Lewy bodies often have memory loss and thinking problems common in Alzheimer’s, but are more likely than people with Alzheimer’s to have initial or early symptoms such as sleep disturbances, well-formed visual hallucinations, and muscle rigidity or other parkinsonian movement features.
Mixed dementia is a condition in which abnormalities characteristic of more than one type of dementia occur simultaneously. Physicians may also call mixed dementia “Dementia – multifactorial.” In the most common form of mixed dementia, the abnormal protein deposits associated with Alzheimer’s disease coexist with blood vessel problems linked to vascular dementia. Alzheimer’s brain changes also often coexist with Lewy bodies.
Symptoms: Mixed dementia symptoms may vary, depending on the types of brain changes involved and the brain regions affected. In many cases, symptoms may be similar to or even indistinguishable from those of Alzheimer’s or another type of dementia. In other cases, a person’s symptoms may suggest that more than one type of dementia is present.
Parkinson’s disease dementia is an impairment in thinking and reasoning that eventually affects many people with Parkinson’s disease. The brain changes caused by Parkinson’s disease begin in a region that plays a key role in movement. As Parkinson’s brain changes gradually spread, they often begin to affect mental functions, including memory and the ability to pay attention, make sound judgments and plan the steps needed to complete a task. Parkinson’s disease is a fairly common neurological disorder in older adults, estimated to affect nearly 2 percent of those older than age 65. The National Parkinson Foundation estimates that 1 million Americans have Parkinson’s
disease. It is estimated that 50 to 80 percent of those with Parkinson’s disease eventually experience Parkinson’s disease dementia
Symptoms: Problems with movement are a common symptom early in the disease. If dementia develops, symptoms are often similar to
dementia with Lewy bodies.
Frontotemporal dementia (FTD) is a group of disorders caused by progressive cell degeneration in the brain’s frontal lobes (the areas
behind your forehead) or its temporal lobes (the regions behind your ears).FTD was once considered rare, but it’s now thought to account for up to 10 to 15 percent of all dementia cases. It’s still believed to be less common than the other types of dementia. In those younger than age 65, FTD may account for up to 20 to 50 percent of dementia cases. FTD used to be called Pick’s disease after Arnold Pick, a physician who in 1892 first described a patient with distinct symptoms affecting language. Some doctors still use the term “Pick’s disease.” Other terms you may see used to describe FTD include frontotemporal disorders, frontotemporal degeneration and frontal lobe disorders. People usually develop FTD in their 50s or early 60s, making the disorder relatively more common in this younger age group. The cell damage caused by frontotemporal dementia leads to tissue shrinkage and reduced function in the brain’s frontal and temporal lobes, which control planning and judgment; emotions, speaking and understanding speech; and certain types of movement.
Symptoms: Typical symptoms include changes in personality and behavior and difficulty with language. Nerve cells in the front and side
regions of the brain are especially affected.
Creutzfeldt-Jakob disease (CJD) is the most common human form of a group of rare (occurring in about one in 1 million people annually worldwide), fatal brain disorders known as prion diseases. Creutzfeldt-Jakob disease causes a type of dementia that gets worse unusually
fast, where the other types typically progress more slowly. Prion diseases, such as Creutzfeldt-Jakob disease, occur when prion protein,
which is found throughout the body but whose normal function isn’t yet known, begins folding into an abnormal three-dimensional shape. This shape change gradually triggers prion protein in the brain to fold into the same abnormal shape. Resulting damage leads to rapid decline in thinking and reasoning as well as involuntary muscle movements, confusion, difficulty walking and mood changes.
Symptoms: Rapidly fatal disorder that impairs memory and coordination and causes behavior changes.
Huntington’s Disease (HD) is a progressive brain disorder caused by a defective gene. This disease causes changes in the central area of the brain, which affect movement, mood and thinking skills. Huntington’s disease is a progressive brain disorder caused by a single defective gene on chromosome 4 — one of the 23 human chromosomes that carry a person’s entire genetic code. This defect is dominant,” meaning that anyone who inherits it from a parent with Huntington’s will eventually develop the disease.
Symptoms: Huntington’s disease usually develop between ages 30 and 50, but they can appear as early as age 2 or as late as 80. The hallmark symptom of Huntington’s disease is uncontrolled movement of the arms, legs, head, face and upper body. Huntington’s disease also causes a decline in thinking and reasoning skills, including memory, concentration, judgment and ability to plan and organize. Huntington’s disease brain changes lead to alterations in mood, especially depression, anxiety, and uncharacteristic anger and irritability. Another common symptom is obsessive-compulsive behavior, leading a person to repeat the same question or activity over and over.
Korsakoff syndrome is a chronic memory disorder caused by severe deficiency of thiamine (vitamin B-1). Korsakoff syndrome is most
commonly caused by alcohol misuse, but certain other conditions also can cause the syndrome. Thiamine (vitamin B-1) helps brain cells produce energy from sugar. When levels fall too low, brain cells cannot generate enough energy to function properly. As a result, Korsakoff syndrome may develop. Korsakoff syndrome is most commonly caused by alcohol misuse, but can also be associated with AIDS, chronic infections, poor nutrition and certain other conditions.