Memory Function and Huntington's Disease: A Systematic Review

This systematic review aimed to identify preserved and impaired memory processes in Huntington's disease (HD), with consideration of disease stage and the specific memory subsystems assessed. A systematic search was conducted in PubMed, ScienceDirect, and Google Scholar up to March 11, 2025. Eligible studies had to be peer-reviewed, had to involve participants aged 18 or older, had to include patients with genetically or clinically confirmed HD, and had to be published in English or French. Risk of bias was assessed using the ROBINS-I tool. A structured narrative synthesis was performed across seven memory subsystems and clinical stages (pre-manifest vs. manifest), and findings were summarized using tables and figures. A total of 136 studies were included. Verbal episodic memory impairments were consistently observed from early stages, particularly in free recall, while recognition was initially preserved. Visual episodic memory showed progressive deficits. Olfactory memory, though rarely examined, appeared to be impaired early. Autobiographical memory was underinvestigated but showed signs of disruption, seemingly independent of executive dysfunction. Semantic memory was generally preserved but showed reduced access without cues. Early-stage impairments were also reported in working memory. Priming was preserved, while complex procedural learning tasks showed variable deficits. Many studies presented methodological limitations, including confounding and lack of blinding. Memory profiles in HD appear heterogeneous and subsystem-specific. Autobiographical memory may constitute a distinct cognitive marker. Improved characterization of memory deficits is crucial to guide the development of targeted cognitive interventions.