Initial memory deficit profiles in patients with a cerebrospinal fluid Alzheimer's disease signature

Alzheimer's disease (AD) clinical onset is usually characterized by a memory complaint and a progressive memory deficit. The proportion of typical medial-temporal amnesia revealing AD remains unknown.

The present study explores the episodic memory impairment profiles by the Free and Cued Selective Recall Reminding Test (FCSRT) in patients with initial memory complaint and a cerebrospinal fluid (CSF) biomarker signature of AD.

Seventy-three patients referred for memory complaint to the Centers for Memory, Resource and Research of Lyon and Montpellier (France) were included consecutively. All patients underwent an extensive neuropsychological examination and had a Mini-Mental State Examination (MMSE) score ≥20 and a positive CSF AD signature. The patients were classified as having mild dementia or prodromal AD. Verbal episodic memory was assessed using the French version of the FCSRT exploring encoding, storage/consolidation, and cued delayed retrieval phases of memorization. Three different memory profiles were identified according to the results of FCSRT.

The median age was 72 year-old [interquartiles: 65-76]. The median MMSE score was 23 [interquartiles: 21-25]. 88% of the patients (n = 64) presented with a medial temporal amnesia profile. The dysexecutive amnesia and normal verbal episodic memory profiles represented respectively 5% (n = 4) and 7% (n = 5). There were no significant differences in term of age, gender, and MMSE score between the three profile groups.

In a population initially presenting with memory complaints and depicting a CSF AD signature, a high proportion of medial temporal amnesia is disclosed as expected, but also a proportion of dysexecutive amnesia and normal FCSRT.