There is currently no strong evidence to suggest CBD is an inherited disease, and no other risk factors, such as toxins or infections, have been identified. Studies of brain tissue of individuals with CBD show certain characteristic cell changes. Similar, although not identical, changes are observed in two other neurodegenerative diseases, Pick's disease and progressive supranuclear palsy. Symptoms of CBD usually begin after age 60. The initial symptoms of CBD are often stiffness, shakiness, jerkiness, slowness, and clumsiness, in either the upper or lower extremities.
Symptoms usually begin on one side of the body, and spread gradually to the other.
CBD is a progressive disease, meaning the symptoms worsen over time. Over the course of one to several years, most people with CBD gradually worsen, with symptoms progressing to involve upper and lower extremities and other body regions. Early in the disease course, it is often difficult to distinguish CBD from similar neurodegenerative diseases. Diagnosis of CBD involves a careful neurological exam, combined with one or more types of laboratory evaluations. CT or MRI scans can also be used in this way, providing images of asymmetric atrophy of the fronto-parietal regions of the brain's cortex, the regions most frequently involved in the disease.