Handgrip and Gait Metrics as Scalable Markers of Physical Health in Schizophrenia and Alcohol Use Disorders

Background: Schizophrenia (SCZ) and alcohol use disorder (AUD) are associated with elevated risks of physical decline and motor dysfunction, which substantially contribute to adverse health outcomes.Although motor abnormalities in these conditions have been widely investigated, objective and scalable assessments of motor function-such as wearable-based measures of handgrip strength and gait-remain underutilized in psychiatric research and clinical practice.This study aimed to compare handgrip strength (HGS) and gait-related motor features between healthy controls (HCs) and two diagnostic groups-SCZ and AUD-using wearable sensor-based assessments.Methods: A total of 434 participants (HCs: n = 210; AUD: n = 80; SCZ: n = 144) completed instrumented Timed Up and Go (iTUG), straight walking, and handgrip strength tests.Fifteen motor features were extracted, including absolute and relative handgrip strength (rHGS) and quantitative gait parameters.Group differences were examined using multivariable linear regression models adjusted for age, sex, and body mass index.Results: Five motor features-HGS, rHGS, walk quality index, symmetry index, and midturning phase duration-significantly differentiated one or both diagnostic groups from HCs after covariate adjustment.In AUD, rHGS showed moderate associations with multiple gait parameters, including walking speed and stride length.In contrast, these associations were weaker in SCZ.Conclusions: Both schizophrenia and alcohol use disorder showed reduced handgrip strength and gait abnormalities (e.g., symmetry) compared with healthy controls.However, motor coordination patterns differed across diagnostic groups: in alcohol use disorder, lower relative handgrip strength was coupled with multiple gait parameters, suggesting more global motor dysfunction, whereas this coupling was weaker in schizophrenia, indicating reduced coordination between upper-and lower-limb motor function.These findings support the potential utility of wearable-based grip and gait metrics as scalable motor functional markers in schizophrenia and alcohol use disorder, with conditional applicability to other psychiatric populations.