OBJECTIVE To determine the role of persistent apathy in rapid loss of autonomy in Instrumental Activities of Daily Living (IADL) in women with Alzheimer s disease (AD), taking into account the grade of cognitive decline. METHODS The study was conducted on 272 women from the French REAL cohort. At inclusion patients had a Mini-Mental State Examination (MMSE) score between 10-26. A rapid functional decline was defined as a yearly drop of 4 points or more on the 14-point IADL Lawton scale. Persistent apathy was defined as a frequency score equal to 3 or 4 on the Neuro-Psychiatric Inventory at the three consecutive 6-monthly assessments. RESULTS 27.6% of women had rapid functional decline in 1 year and 22.1% of them had persistent apathy. A logistic regression analysis showed that, in addition to cognitive decline, persistent apathy plays a role in rapid functional decline in 1 year. For example, for a 3-point decline in MMSE in 1 year, the probability of a rapid loss in IADL is 0.45 for women with persistent apathy compared with 0.28 for those without persistent apathy. CONCLUSIONS In this study, a rapid loss in IADL score was partly explained by persistent apathy.