Cognitive and behavioral involvement in spinal and bulbar muscular atrophy (SBMA): a systematic review

Objective: This study aimed at reviewing currently available evidence on cognitive and behavioral involvement in spinal and bulbar muscular atrophy (SBMA). Methods: This review was performed in accordance with the 2020 PRISMA guidelines. We included case reports/series and group studies reporting data on the neuropsychological features of SBMA patients. Results: Out of 123 unique records identified, 11 studies were included (N = 5 case reports/series; N = 6 group studies), comprising 151 SBMA patients. Among case reports and series, 6 out of 10 patients were reported to exhibit some degree of neuropsychological involvement, with two being diagnosed with a dementia condition resembling the characteristics of behavioral variant-frontotemporal dementia. Three of the 6 case-control studies found no cognitive differences between SBMA patients and healthy controls. Cognitive deficits reported in group studies mostly involved the executive, attentional, memory and visuo-spatial/-constructive domains. Conclusions: The available evidence on cognitive and behavioral involvement in SBMA is scarce and conflicting. However, it is conceivable that at least some patients may exhibit dysexecutive-type changes, possibly reflecting a frontal system involvement.