A pilot study: handgrip as a predictor in the disease progression of SCA3

BACKGROUND: Spinocerebellar ataxia type 3 (SCA3) is an inherited, autosomal, and rare neurodegenerative disease. Serum/plasma biomarkers or functional magnetic resonance imaging used to assess progression, except for neurological examinations, is either inconvenient or expensive. Handgrip strength (HGS) may be considered as a biomarker to predict the progress of SCA3 and align with the alteration of plasma neurofilament light chain (NfL) and Scale for the Assessment and Rating of Ataxia (SARA).

METHODS: Patients with SCA3 and healthy subjects were recruited from Changhua Christian Hospital. SARA, body mass index (BMI), and NfL were obtained for both groups. HGS was measured using a Jamar Plus + hand dynamometer.

RESULTS: This study recruited 31 patients and 36 controls. HGS in the SCA3 group revealed a profound decrease (P < 0.001) compared with normal subjects. HGS also had a negative correlation with SARA (r =  - 0.548, P = 0.001), NfL (r =  - 0.359, P = 0.048), and a positive correlation with BMI (r = 0.680, P < 0.001). Moreover, HGS/BMI ratio correlated with SARA (r =  - 0.441, P = 0.013). Controlling for gender and age, HGS still correlated with the above clinical items. The initial hypothesis was also proved in SCA3 84Q transgenic mice, showing grip strength weakness compared to normal mice.

CONCLUSIONS: HGS can be an alternative tool to assess the clinical severity of SCA3. Further research is needed to investigate the underlying mechanisms.