Huntington's Disease

Juvenile HD

Some affected individuals develop symptoms before age 20. Initial signs of HD have been reported before puberty, or, in rare cases, in children as young as four years of age or younger.

In those with juvenile HD, progressive loss of cognitive skills occurs along with increasing muscle stiffness and resistance to movement (rigidity) and relative slowness of movement (bradykinesia). This form of the disease is sometimes referred to as "akinetic-rigid" or "Westphal variant" HD. Although it most commonly occurs in juvenile cases, the rigid form of the disease has also been reported in some adults.

Typical findings associated with juvenile HD include a sudden decline in academic performance, changes in handwriting, behavioral problems, and seizures (epileptic convulsions). In addition, rather than the chorea typically seen in adult-onset disease, the movement abnormalities of juvenile HD tend to resemble those observed in Parkinson's disease. Individuals with juvenile HD may experience muscle rigidity and bradykinesia as well as tremors; brief, "shock-like" spasms of certain muscles or muscle groups (myoclonus); progressively impaired control of voluntary movement (ataxia); and dystonia. Juvenile HD typically has a relatively rapid disease progression as compared with that observed in adult-onset disease.