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Background Adults with Down syndrome (DS) are at increased risk of developing Alzheimer's disease (AD) due to genetic predisposition. Identification of patients with AD is difficult since intellectual disabilities (ID) may confound diagnosis. The objective of this study was to evaluate the ability of the French version of the modified cued recall test (mCRT) to distinguish between subjects with and without AD in the adult DS population. Methods This was a retrospective, single‐centre, medical records study including data between March 2014 and July 2020. Adults aged ≥30 years with DS who had at least one mCRT record available were eligible. Age, sex and ID level were extracted, and subjects were attributed to three groups: patients with AD, patients with co‐occurring conditions that may impact cognitive function and subjects without AD. mCRT scores, adjusted by sex, age and ID level, were compared between groups. The optimal cut‐off value to distinguish between patients with and without AD was determined using the receiver operating characteristic curve. The impact of age and ID level on mCRT scores was assessed. Results Overall, 194 patients with DS were included: 12 patients with AD, 94 patients with co‐occurring conditions and 88 healthy subjects. Total recall scores were significantly lower (P < 0.0001) in patients with AD compared with healthy subjects. The optimal cut‐off value to discriminate between patients with AD and healthy subjects was 22, which compares well with the cut‐off value of 23 originally reported for the English version of the mCRT. Patients aged 30–44 years had higher mCRT total recall scores compared with patients aged ≥45 years (P = 0.0221). Similarly, patients with mild ID had higher mCRT scores compared with patients with severe ID (P < 0.0001). Interpretation The mCRT is a sensitive tool that may help in the clinical diagnosis of AD in subjects with DS. Early recognition of AD is paramount to deliver appropriate interventions to this vulnerable population.