Huntington’s disease (HD) is a progressive, inherited and degenerative brain disorder that produces physical, mental and emotional changes. Named after George Huntington, the physician who first described the illness in 1872, Huntington’s disease was formerly known as Huntington’s chorea, from the Greek for choreography, or dance. The name refers to the involuntary, jerky movements that can develop in later stages of the illness. Approximately 30,000 people in the United States have Huntington’s disease, which affects men and women equally across all ethnic and racial lines. While more common in adults, juvenile Huntington’s accounts for about one-sixth of all cases. Every child of a parent who carries the HD gene has a 50% chance of inheriting the abnormal gene. A child who inherits the Huntington’s gene will eventually develop the illness, although onset typically does not occur until ages 35-50 or later. The good news: if a child does not inherit the Huntington’s gene, there is no risk of developing Huntington’s disease or of passing it on, since Huntington’s does not “skip” generations.
Genetic testing can diagnose Huntington’s at every stage of the life cycle. There are three categories for testing:
- Prenatal testing, either amniocentesis (a sample of fluid from around the fetus), or chorionic villus sampling (CVS—a sample of fetal cells from the placenta), will indicate whether the baby has inherited the gene for Huntington’s.
- Pre-symptomatic testing is available to people who are at risk of inheriting Huntington’s disease from a parent, but don’t have symptoms and don’t know whether or not they carry the gene.
- Confirmatory testing determines whether a person showing what appear to be the symptoms of HD, actually has the disease. Neurological and psychological tests are also conducted to arrive at a conclusive diagnosis of Huntington’s disease.
Pre-symptomatic testing is usually requested or recommended when a parent is known to have, or is suspected of having, Huntington’s disease, or an at-risk parent is still living, but doesn’t know whether they carry the Huntington’s gene.
Because Huntington’s disease affects the mind, body and emotions, symptoms often mimic other conditions. The general symptoms in early stages can include poor memory; difficulty making decisions; mood changes such as increased depression, anger or irritability; a growing lack of coordination, twitching or other uncontrolled movements; difficulty walking, speaking, and/or swallowing. The order in which symptoms develop will vary from person to person. Over time, these symptoms may progress to a stage where the person loses the ability to recognize familiar objects, people and places. A person with Huntington’s disease may eventually begin to exhibit psychotic behavior, such as delusions, hallucinations, inappropriate behavior (e.g., unprovoked aggression) and paranoia.
Individuals with HD have a progressive loss of cells in the part of the brain called the basal ganglia. These cells are dying and are not being replaced. Over time, thousands of brain cells will be lost, and with their loss, patients experience a decline in emotional, physical and reasoning abilities. At autopsy, the brain of a person with advanced Huntington disease weighs less than a normal brain, and there are areas of substantial cell death. When a slice of Huntington’s brain is put next to a slice from a normal brain, you will see that the striatum (the caudate nucleus, putamen and nucleus accumbens) is severely atrophied in the Huntington’s brain. In addition, the cerebral cortex is atrophied in the Huntington’s brain.
The emphasis today is on living positively with Huntington’s Disease. An integrated, multi-disciplinary approach focuses on the triad of diet and supplements, exercise and spiritual and psychosocial support. There are no treatments which will stop or reverse the disease at the present time. It is possible to treat some of the effects, such as depression and jerking movements, with various medications. Improvements in general health, such as good nutrition, will bring about improvements in the condition of the person and in their enjoyment of life. Many scientists are working on finding treatments and a cure for Huntington disease.