What you have to prove
Qualify via: (1) disorganization of motor function in two extremities with extreme limitation in standing, balancing, or upper-extremity use, OR (2) marked limitation in one area of cognitive functioning AND marked limitation in physical functioning.
Medical evidence SSA expects
Neurologist's diagnosis (typically Parkinson's specialist), response to levodopa trial, DAT scan if performed, tremor and gait evaluations, medication history, and functional assessments.
Common misconceptions
Early-stage Parkinson's with good medication response usually doesn't qualify. Most approvals come in mid-to-late stage when motor fluctuations or cognitive symptoms are marked.
Didn't meet the listing? You can still qualify via a Medical-Vocational
Allowance — SSA's determination that your residual functional capacity, combined with
your age, education, and work history, leaves no jobs you can do. See our
appeals guide for what to do after an initial denial.