Avoid labeling people when possible. In scientific writing, participants in a study tend to lose their individuality and may be broadly categorized as objects (with noun forms such as the gays and the elderly) and people with disabilities may be equated with their conditions — the amnesiacs, the depressives, the schizophrenics, for example. One solution is to use adjectival forms (e.g., “gay men,” “older adults,” “amnesic patients”). Another solution is to “put the person first,” followed by a descriptive phrase (e.g., “people diagnosed with schizophrenia”).
From the APA Publication Manual (6th ed) (2010): Section 3.11, Reducing Bias in Language. Guideline 2: Be Sensitive to Labels.