Types of dementia
Alzheimer’s disease accounts for 50 to 70 percent of cases of dementia. This is a progressive dementia featuring short term memory loss, word-naming problems, difficultly performing complex tasks, judgement and perception problems, and way-finding difficulties. Over time, the person gradually loses the ability for self-care.
Dementia with Lewy bodies often starts with wide variations in attention and alertness. Individuals affected by this illness often experience visual hallucinations as well as muscle rigidity and tremors similar to those associated with Parkinson’s disease. Parkinson’s disease affects control of movement, resulting in tremors, stiffness and impaired speech. Many individuals with Parkinson’s disease also develop dementia in later stages of the disease.
Mixed dementia is a condition in which Alzheimer’s disease and vascular dementia, or Alzheimer's and Lewy body dementia, occur together.
Vascular dementia, often considered the second most common type of dementia, refers to impairment caused by reduced blood flow to parts of the brain. One type may develop after a single major stroke blocks blood flow to a large area of brain tissue. Symptoms of vascular dementia can be similar to Alzheimer’s disease. They include problems with memory, confusion and difficulty following instructions. In some cases, the impairment associated with vascular dementia can occur in “steps” rather than in the slow, steady decline usually seen in Alzheimer’s.
Mild cognitive impairment (MCI) is becoming an increasingly common diagnosis as people concerned about early memory change seek medical evaluation. While MCI may be a pre-clinical stage of Alzheimer's disease, some people do not progress on to Alzheimer's. People with MCI show some deviation from the normal cognitive range when evaluated with cognitive testing; however, their normal daily function is not impacted by the memory changes they themselves have noticed.
Frontotemporal dementias or frontotemporal lobar degeneration (FTLD) are a group of progressive disorders that affect the frontal and temporal lobes of the brain. It can be difficult to distinguish from Alzheimer’s disease, Parkinson’s disease or ALS. Personality changes and disorientation often occur before memory loss.
Huntington’s disease is another form of dementia which is an inherited, progressive disorder that causes irregular movements of the arms, legs and facial muscles, personality changes, and a decline in the ability to think clearly.
Creutzfeldt-Jakob disease (CJD) (CROYZ-felt YAH-kob) is a rare, rapidly fatal disorder that impairs memory and coordination, and causes behavior changes.
Normal pressure hydrocephalus (NPH) is caused by a buildup of fluid in the brain. The cause of most cases is unknown. Symptoms include difficulty walking, memory loss and the inability to control urine. Sometimes NPH can be corrected with surgery to drain the excess brain fluid.