The onset of the disease is slow and subtle. The first symptoms usually begin in the fourth or fifth decades of life although occasionally they may start in childhood or be delayed into the 60s.
In the early stages of the disease, personality changes such as depression, dementia, or other psychiatric changes may be noticed. This sometimes happens before or at the same time as movement disorders. Abnormal motions occur on one side of the body, commonly affecting the face and arms. Symptoms include facial movements that look like mild grimacing and speech problems. When the person becomes emotionally upset, symptoms tend to worsen and become more severe.
As the disease progresses, abnormal movements become faster – almost violent – and purposeless. Patients tend to display jerky, almost dance-like motions (chorea). There is often severe dementia associated with this late stage of the disease.
Eventually, people with this disease are unable to look after themselves and need help with daily activities and functions such as eating, hygiene, and toileting. People tend to become bedridden and may suffer complications such as congestive heart failure and pneumonia.