I found this on the ADA website:
"An individual with a disability is a person who --
Has a physical or mental impairment that substantially limits one or more major life activities, or
Has a record of such an impairment, or
Is regarded as having such an impairment.
Examples of physical or mental impairments include, but are not limited to, such contagious and noncontagious diseases and conditions as orthopedic, visual, speech, and hearing impairments; cerebral palsy, epilepsy, muscular dystrophy, multiple sclerosis, cancer, heart disease, diabetes, mental retardation, emotional illness, specific learning disabilities, HIV disease (whether symptomatic or asymptomatic), tuberculosis, drug addiction, and alcoholism."
Not sure if that answers your question. If not, go to the ADA homepage and read the questions and answers section. Hope that helps!