In awkward constructions, such as when the noun following the eponym is omitted, the possessive form becomes preferred.

The patient's husband suffers from Alzheimer's.

Further:
AAMT first advocated dropping the possessive form of eponyms in 1990. We adopted this standard because it promotes consistency and clarity. More recently, the AMA Manual of Style, Stedman's Medical Dictionary and Dorland's Illustrated Medical Dictionary have acknowledged the trend away from the possessive form.

It is important to note, however, that use of the possessive form remains an acceptable alternative if dictated and/or if indicated as the preference by the employer or client.