Neuropsychological functioning and progression in Lafora disease.

OBJECTIVE

Lafora disease (LD) is a rare and severe form of progressive myoclonus epilepsy characterized by cognitive decline that ultimately leads to dementia. However, its cognitive features and adaptive functioning remain poorly understood. This study aimed to characterize the neuropsychological profile of LD and its progression.

METHODS

In this monocentric cohort study, consecutive LD patients were administered a battery including cognitive measures (Leiter-3, Children's Color Trail Test [CCTT], Wechsler Adult Intelligence Scale-IV Vocabulary, and Visual-Motor Integration [VMI] test) and the Vineland Adaptive Behavior Scales, Second Edition (Vineland-II). Longitudinal follow-up data were collected after 12 months. Scores were normalized into z-scores for analysis.

RESULTS

Fourteen patients (six females) were included. Mean age at onset was 12.6 ± 2.0 years (range = 10-17), and mean age at baseline assessment was 16.5 ± 2.6 years (range = 13-19). Mean Leiter-3 intelligence quotient (IQ) was 79.8 ± 22.8 (range = 45-120); IQ was impaired in 10 of 14 patients (71%; extremely low, n = 6; borderline, n = 4). Executive dysfunction was the most prominent deficit; impairment was observed in 12 of 14 (86%) on CCTT, nine of 12 (75%) on sustained attention, eight of 12 (67%) on congruent Stroop, and 10 of 12 (83%) on incongruent Stroop. VMI was impaired in 10 of 14 (71%), and verbal abilities in four of seven (57%). Mean Vineland-II Adaptive Behavior Composite score was 82.7 ± 33.7 (range = 20-128), in the moderately low range, mainly driven by reduced communication scores (75.9 ± 36.3, range = 20-120). Nine patients completed 12-month follow-up, showing significant decline in IQ, executive functions, and visuomotor integration (all p < .05), and adaptive functioning showed a downward trend.

SIGNIFICANCE: LD is characterized by prominent executive dysfunction accompanied by reduced adaptive communication skills, even in the initial stages. The CCTT was sensitive in detecting early deficits and cognitive decline, supporting its use in clinical practice and research. These findings highlight the need for standardized neuropsychological testing and support its role in tracking disease progression and as an outcome measure in clinical trials.