This study explores the longitudinal relationship between patient characteristics and use of 4 drug classes (antihypertensives, antidepressants, antipsychotics, and hormones) that showed significant changes in use rates over time in patients with Alzheimer disease. Patient/caregiver-reported prescription medication usage was categorized by drug class for 201 patients from the Predictors Study. Patient characteristics included use of cholinesterase inhibitors and/or memantine, function, cognition, living situation, baseline age, and sex. Assessment interval, year of study entry, and site were controlled for. Before adjusting for covariates, useage increased for antihypertensives (47.8% to 62.2%), antipsychotics (3.5% to 27.0%), and antidepressants (32.3% to 40.5%); use of hormones decreased (19.4% to 5.4%). After controlling for patient characteristics, effects of time on the use of antidepressants were no longer significant. Antihypertensive use was associated with poorer functioning, concurrent use of memantine, and older age. Antipsychotic use was associated with poorer functioning and poorer cognition. Antidepressant use was associated with younger age, poorer functioning, and concurrent use of cholinesterase inhibitors and memantine. Hormone use was associated with being female and younger age. Findings suggest accurate modeling of the Alzheimer disease treatment paradigm for certain subgroups of patients should include antihypertensives and antipsychotics in addition to cholinesterase inhibitors and memantine.