Overview

Alzheimer's disease (AD) is characterized by anterograde amnesia, the inability to memorize and remember events occurring after the cerebral lesion. Among the most frequently reported psycho-behavioural symptoms are repetitive behaviours (RB), defined as actions or statements repeated in an inappropriate and non-functional way.

The most commonly used tool to assess repetitive behaviours is the Stereotypy Rating Inventory (SRI). It is a questionnaire that evaluates five types of stereotypical behaviour: eating, wandering, speech, movements, and daily routines. The frequency and severity of the behaviours are reported, and a total score can be calculated.

There is no consensus on the types of repetitive behaviours observed specifically in AD, their frequency, or their cognitive correlates, nor is there a hypothesis explaining why this symptomatology does not occur in all AD patients. Furthermore, certain parameters, such as anosognosia (lack of awareness of the disorders), have not been linked to RB in the literature. We propose to evaluate patients with anterograde amnesia in terms of cognition and behaviour-specifically, the presence or absence of both RB and anosognosia-to examine possible links between cognitive performance, anosognosia, and RB.

Moreover, there is no theoretical framework explaining the emergence of RB in amnesia. We suggest that CRs are linked to the lack of memory updating in the cognitive system. Since episodic memory no longer provides mnemonic feedback, previously encountered stimuli may trigger repeated behaviour.

To test this hypothesis, we decided to conduct a multicenter, cross-sectional, case-control study. Patients with AD, with or without RB, as well as healthy subjects, were repeatedly presented with sentence starters to complete freely, with the aim of studying the similarity of responses across sessions for each participant. We also included a patient with pure anterograde amnesia from a previously submitted case study protocol, who exhibited pronounced RB symptomatology following neurosurgery (non-AD patient), to examine the phenomenon in a non-Alzheimer's context.

Eligibility

Inclusion Criteria:

I- RB+ (n=42) and RB- (n=30) groups :

1. MMSE \> 20
2. 1 reliable family caregiver identified per patient
3. Patients under legal protection (guardianship/curatorship) or not
4. Selection:

4.a. AD patients with an SRI score \> 0 will constitute the RB+ subgroup. 4.b. Only the first 30 patients included will undergo V2, V3, and V4. The first 30 AD patients included with an SRI score = 0 will constitute the RB- subgroup.

II- Control group: healthy subjects (n=30)

1. Healthy subjects
2. MMSE ≥ 26/30
3. Men and women matched to AD patients in terms of age and sociocultural level.
4. Healthy subjects will be included by the CMRR in Limoges

III- Control group: Patient with anterograde amnesia (AA) (n=1):

1. The patient with anterograde amnesia is a patient who participated in the ANISAAFORNIX study (another study submitted by the investigator) and is included in this study due to rich RB symptomatology. He is a 54-year-old man with lesions of the fornix following complications from neurosurgery, which led to severe anterograde amnesia. This patient does not have AD.
2. This patient is under legal protection (guardianship).
3. Patient monitored and included at the CMRR in Limoges.

Exclusion Criteria: I- RB+ and RB- groups and healthy subjects:

1. Isolated participants (without an identified caregiver) (RB+ and RB- groups)
2. Participants must not have a history of alcohol or other substance dependence in the past 12 months.
3. Participants must not have any other neurological condition (with the exception of patients with AA anterograde amnesia). Any history of moderate to severe head trauma, stroke, or developmental disorders is a criterion for exclusion.