Grip strength asymmetry in depressed boys

Objective: The purpose of this experiment was to investigate the influence of depressed mood on functional motor asymmetry among school-aged boys. Thu s, left- and right-hand grip strength as well as fatigue across successive trials was examined among 38 right-handed school-aged boys, half of whom ha d been classified as depressed (n = 19) and the other half as nondepressed (n = 19). Background: There is support in the literature that depressed ind ividuals experience relative right anterior activation, and previous report s of functional motor asymmetries among depressed adults are generally supp ortive of this notion. To date, however, little is known regarding the nenr opsychology of depression as it may pertain to children; in particular, the possibility of functional motor asymmetry within this population has yet t o be explored, Method: Participants were asked to squeeze a hand dynamomete r four times successively with each hand. The order of hand presentation wa s counterbalanced, and the dependent measure was in kilograms. Results: As hypothesized, depressed boys failed to demonstrate asymmetry for grip stren gth, although nondepressed boys exhibited right-hand grip strength. In addi tion, based on trend, right-hand grip strength for depressed boys fatigued more rapidly across successive trials than did right-hand grip strength for nondepressed boys, in contrast, depressed boys maintained left-hand grip s trength longer across successive trials than did nondepressed boys. Conclus ions: The data are interpreted as consistent with current neuropsychologica l theories of emotion, particularly depression, and suggest that the functi onal motor asymmetries (i.e., failure to demonstrate asymmetric grip streng th) observed in depressed adults are also present among depressed children. Implications for increased right hemisphere activation, decreased left hem isphere activation, or a combination of both are discussed.