Prose memory impairment in amyotrophic lateral sclerosis patients is related to hippocampus volume

Background and purpose: Thirty per cent of amyotrophic lateral sclerosis (ALS) patients have non-motor symptoms, including executive and memory deficits. The in vivo anatomical basis of memory deficits in ALS has not been elucidated. In this observational study, brain atrophy in relation to memory function was investigated in ALS patients and controls.

Methods: Twenty-six ALS patients without dementia and 21 healthy volunteers matched for gender, age and education level underwent comprehensive neuropsychological evaluation and T1- and T2-weighted 3 T magnetic resonance imaging scanning of the brain. Grey and white matter brain volumes were analysed using voxel-based morphometry and age related white matter changes were assessed. The most frequently abnormal memory test (<2 SD below normative data corrected for age, gender and education) was correlated with regional brain volume variations by multiple regression analyses with age, gender and total grey matter volumes as covariates.

Results: Immediate and delayed story recall scores were abnormal in 23% of ALS patients and correlated to bilateral hippocampus grey matter volume (r = 0.52 for both memory tests; P < 0.05; corrected for age, gender and total grey matter volume). This correlation was not found in healthy controls with similar age, education, anxiety and depression levels and white matter changes.

Conclusions: Prose memory impairment is a frequent finding in this cohort and is associated with hippocampus volume in ALS patients without dementia. These findings complement previous hippocampus changes in imaging studies in ALS and suggest involvement of the hippocampus in cognitive dysfunction of ALS.