5. Dementia caused by Huntington's disease (HD)
What it is: This fatal disease is caused by a genetic abnormality that destroys certain nerve cells in the brain and lowers levels of neurotransmitters. Mental, emotional, and behavioral declines follow.
Although HD victims are born with the defective gene, they don't usually experience symptoms until middle age. If a parent has the defective gene, there's a 50 percent chance that a child will have inherited the gene. Some 30,000 Americans have HD.
How the symptoms compare to Alzheimer's: Common symptoms include personality changes, mood swings, and disorientation. Attention and judgment can be impaired early in the disease, while memory loss occurs later.
As with Parkinson's, someone with Huntington's disease has involuntary movements that appear jerky, clumsy, or irregular. They may appear to fidget. Eventually they lose the ability to walk, talk, and swallow.
How it's diagnosed and treated: Huntington's disease can be diagnosed by a blood test to look for the genetic defect. There's no cure or medical treatment, so treatment focuses on improving quality of life.
