OBJECTIVE: To assess effects of quality of life (QOL), spirituality, and religiosity on rate of progression of cognitive decline in Alzheimer disease (AD). METHODS: In this longitudinal study, we recruited 70 patients with probable AD. The Mini-Mental State Examination was used to monitor the rate of cognitive decline. Religiosity and spirituality were measured using standardized scales that assess spirituality, religiosity, and organizational and private religious practices. We conducted a simultaneous multiple linear regression analysis for factors contributing to rate of cognitive decline. RESULTS: After controlling for baseline level of cognition, age, sex, and education, a slower rate of cognitive decline was associated with higher levels of spirituality (p < 0.05) and private religious practices (p < 0.005). These variables accounted for 17% of the total variance [F(11,58) = 2.24, p < 0.05]. There was no correlation between rate of cognitive decline and QOL. CONCLUSION: Higher levels of spirituality and private religious practices, but not quality of life, are associated with slower progression of Alzheimer disease.