Progressive dementias Types of dementias that are not reversible and worsen over time include:
- Alzheimer’s disease. In people age 65 and older, Alzheimer’s disease is the most common cause of dementia. People generally may develop symptoms after age 60, but some people may have early-onset forms of the disease, often as the result of a defective gene. Although in most cases the exact cause of Alzheimer’s disease isn’t known, plaques and tangles are often found in the brains of people with Alzheimer’s. Plaques are clumps of a protein called beta-amyloid, and tangles are fibrous tangles made up of tau protein. Certain genetic factors also may make it more likely that people will develop Alzheimer’s. Alzheimer’s disease usually progresses slowly over about eight to 10 years. Your cognitive abilities slowly decline. Eventually, the affected areas of your brain don’t work properly, including parts of your brain that control memory, language, judgment and spatial abilities.
- Vascular dementia. Vascular dementia, the second most common type of dementia, occurs as a result of brain damage due to reduced or blocked blood flow in blood vessels leading to your brain. Blood vessel problems may be caused by stroke, infection of a heart valve (endocarditis) or other blood vessel (vascular) conditions. Symptoms usually start suddenly and often occur in people with high blood pressure or people who have had strokes or heart attacks in the past. Several different types of vascular dementia exist, and the types have different causes and symptoms. Alzheimer’s disease and other dementias also may be present at the same time as this dementia.
- Lewy body dementia. Lewy body dementia affects approximately 10 percent of people with dementia, making it one of the most common types of dementia. Lewy body dementia becomes more common with age. Lewy bodies are abnormal clumps of protein that have been found in the brains of people with Lewy body dementia, Alzheimer’s disease and Parkinson’s disease. Lewy body dementia symptoms are similar to symptoms of Alzheimer’s disease. Its unique features include fluctuations between confusion and clear thinking (lucidity), visual hallucinations, and tremor and rigidity (parkinsonism). People with Lewy body dementia often have a condition called rapid eye movement (REM) sleep behavior disorder that involves acting out dreams.
- Frontotemporal dementia. This type of dementia tends to occur at a younger age than does Alzheimer’s disease, generally between the ages of 50 and 70. This is a group of diseases characterized by the breakdown (degeneration) of nerve cells in the frontal and temporal lobes of the brain, the areas generally associated with personality, behavior and language. Signs and symptoms of frontotemporal dementia can include inappropriate behaviors, language problems, difficulty with thinking and concentration, and movement problems. As with other dementias, the cause isn’t known, although in some cases this dementia is related to certain genetic mutations
- Huntington’s disease. This inherited disease causes certain nerve cells in your brain and spinal cord to waste away. Signs and symptoms usually appear during your 30s or 40s. People may experience personality changes, such as irritability or anxiety. The condition causes a severe decline in thinking (cognitive) skills over time. Huntington’s disease also causes weakness and difficulty with walking and movement.
- Traumatic brain injury. This condition is caused by repetitive head trauma, such as experienced by boxers, football players or soldiers. Depending on the part of the brain that’s injured, this condition can cause dementia signs and symptoms such as uncoordinated movement and impaired speech, as well as slow movement, tremors and rigidity (parkinsonism). Symptoms may not appear until many years after the actual trauma. A person who has experienced a single traumatic head injury could develop a similar condition called post traumatic dementia, which may cause symptoms such as long-term memory problems.
- Creutzfeldt-Jakob disease. This rare brain disorder usually occurs in people without risk factors. This condition may be due to an abnormal form of a protein. Creutzfeldt-Jakob disease sometimes may be inherited or caused by exposure to diseased brain or nervous system tissue. Signs and symptoms of this fatal condition usually appear around age 60 and initially include problems with coordination, memory, thinking and vision. Symptoms worsen over time and may include the inability to move or talk, blindness, or infections.
- Parkinson’s disease. Many people with Parkinson’s disease eventually develop dementia symptoms (Parkinson’s disease dementia).