Cognitive performance of children with spinal muscular atrophy: A systematic review.

UNLABELLED: Spinal muscular atrophy (SMA) is genetic and progressive, caused by large bi-allelic deletions in the SMN1 gene, or the association of a large deletion and a null variant.

OBJECTIVE

To evaluate the evidence about cognitive outcomes in spinal muscular atrophy (SMA).

METHODS

Searches on the PUBMED/Medline, Web of Knowledge and Scielo databases retrieved 26 studies (1989 to 2019, descriptors "spinal muscular atrophy" and "cognition"). Nine studies were selected according to the eligibility criteria: (1) cognition tested in individuals with SMA; (2) written in English or Spanish. The Risk of Bias in Non-Randomized Studies of Interventions was used to describe design, bias, participants, evaluation protocol and main findings. This study was registered on the International prospective register of systematic reviews (PROSPERO).

RESULTS

Three studies described normal cognition. In another three studies, cognitive outcomes were above average. Cognitive impairment was found in three studies. Poor cognitive performance was more frequently reported in studies that were recent, included children with SMA type I and that employed visual/auditory attention and executive function tests. Protocols and cognitive domains varied, precluding metanalysis.

CONCLUSION

The severity of motor impairment may be related to cognitive outcomes: studies that included a higher number/percentage of children with SMA type I found cognitive impairment. The establishment of gold-standard protocols is necessary. Further studies should compare the cognitive outcomes of subjects with SMA types I to IV.