Investigation of hand functions in individuals with cannabis and its derivatives use disorder

The present study was aimed to compare the grip/pinch strengths and manual dexterity of individuals with and without the use of cannabis and its derivatives.

A cross-sectional prospective study was conducted with 66 individuals, including 33 cases with the use of cannabis (and its derivatives) and 33 age- and sex-matched controls. Grip and pinch strengths were evaluated with a dynamometer. The Nine-Hole Peg Test (9HPT), Minnesota Manual Dexterity Test (MMDT), and Michigan Hand Outcomes Questionnaire (MHQ) were used to assess the hand function.

The hand grip strength and dominant hand 2-point pinch (2PP) grip strength were less in individuals with substance use disorder (SUD) (p < 0.05). The 9HPT duration of the SUD patients was higher (p < 0.05). On the other hand, the MMDT insertion and rotation test results were different between the groups (p < 0.05). Grip strength was related with the MMDT insertion and rotation tests (r =  -0.411 to -0.480). There was significant correlation between grip strength with dominant hand 9HPT (r =  -0.370) and between dominant hand 3-point pinch (3PP) strength with MMDT insertion (r =  -0.378). In addition, dominant hand 2PP strength was correlated with overall hand function of MHQ (r = 0.382).

The individuals with cannabis use disorder showed reduced grip strength on both sides and decreased 2PP strength on the dominant side compared to healthy individuals. In addition, there is a decrease in the hand skills of individuals with cannabis use disorder. Decreased grip strength of individuals with cannabis use disorder affected their hand skills negatively.