Decreased diffusion tensor image analysis along the perivascular space index is related with clinical classification in essential tremor

The glymphatic dysfunction involved in various neurodegenerative diseases. However, the relationship between glymphatic activity and essential tremor (ET) has not been fully elucidated. Our study explored the impact of glymphatic function on ET and its clinical classification. Participants comprised 37 pure ET, 38 ET-plus and 50 normal controls. Glymphatic function was evaluated via the diffusion tensor image analysis along the perivascular space (DTI-ALPS) index. Statistical comparisons of DTI-ALPS index among patients with pure ET, those with ET-plus and normal controls were conducted using general linear model analysis. Age, gender and disease duration were included as confounding variable. To confirm the relation between the DTI-ALPS index and the clinical characteristics of pure ET and ET-plus, we conducted partial Spearman rank correlation analyses while controlling for age and disease duration. The DTI-ALPS index in ET-plus patients was significantly lower than that in normal controls (<i>P</i> = 0.004) and pure ET patients (<i>P</i> = 0.010). In ET-plus patients, the DTI-ALPS index demonstrated a significant inverse relationship with disease duration (<i>r</i> = -0.330, <i>P</i> = 0.043). No significant correlations were found between the DTI-ALPS index and clinical severity of ET (all <i>P</i> > 0.05). We have identified for the first time that DTI-ALPS index could be used as a potential biomarker for the clinical classification of ET. The DTI-ALPS index was intimately correlated to disease duration in ET-plus patients.