SMA May Be Linked to Cognitive Impairment in Chinese Patients

In a recent study published in Frontiers in Neurology, a cohort of Chinese adult patients with spinal muscular atrophy (SMA) type III exhibited degrees of cognitive impairment compared with healthy patients.

Cognitive Impairment Model | image credit: Pol Solé - stock.adobe.com

For the majority of the disease’s history, SMA has been considered solely a disease of the motor neurons; however, emerging evidence suggests that SMA can impact multiple non-motor regions. These discoveries have encouraged research on whether SMA impacts cognitive performance.

As the authors of the current study note, many of these studies have been conducted throughout North America and Europe; however, distinguishable SMA mutations have been discovered in Chinese patients, and data on SMA affecting these populations is limited.

Research on the cognitive impacts of SMA has been controversial, and not much attention has been given to adult patients with SMA in this area. The present authors believe that the distinct cultural backgrounds and clinical characteristics of Chinese patients compared with European or North American patients could contribute to variations in their cognitive profiles in relation to SMA. To investigate, researchers conducted a study on Chinese patients with SMA type III to evaluate the associations between cognitive function and clinical features.

A total of 22 adult patients with SMA type III alongside 20 healthy controls were enrolled between October 2021 and May 2023. None of the patients with SMA type III had yet been treated with disease-modifying drugs. Motor function was assessed using the Hammersmith Functional Motor Scale Expanded (HFMSE), the 6-Minute Walk Test (6MWT), and the Revised Upper Limb Module (RULM) assessment. Additionally, the Montreal Cognitive Assessment (MoCa), Verbal Fluency Test (VFT), Stroop Color-Word Interference Test (SCWIT), Auditory Verbal Learning Test (AVLT), Attention Network Test, Wisconsin Card Sorting Test (WCST), Digital Span, Hamilton Depression Rating Scale (HAMD), and Hamilton Anxiety Rating Scale (HAMA) were used to evaluate aspects of general intelligence and cognitive function, memory, language, depression, anxiety, executive function, attention, among other variables.

Results showed that patients with SMA scored lower than controls in aspects of the SCWIT and VFT ( P < .05). Among the domains of the WCST, patients with SMA had worse performances than controls in regard to total errors, perseverative and non-perseverative errors, and perseverative responses (P < .05). Furthermore, patients with SMA registered higher anxiety and depression scores than controls (P < .05) and scoring from the ANT revealed they also had certain deficiencies in their executive control networks, such as mean reaction time (P < .05).

Overall, this Chinese cohort demonstrated that adult patients with SMA type III may have deficits related to executive functioning, which could be associated with the effects of depression, anxiety, disease severity, or degrees of physical impairment. Although these findings add valuable insights into cognitive performance in adult patients with SMA, research and information in this field remains limited and the authors encourage further cognitive studies be conducted to gain a more holistic understand of the driving factors at work.

Reference

Hu Y, Wei L, Li A, et al. Cognitive impairment in Chinese adult patients with type III spinal muscular atrophy without disease-modifying treatment. Front Neurol. Published online November 3, 2023. doi:10.3389/fneur.2023.1226043