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. Thus, 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 had been classified as depressed (n = 19) and the other half as nondepressed (n = 19).


BACKGROUND
There is support in the literature that depressed individuals experience relative right anterior activation, and previous reports of functional motor asymmetries among depressed adults are generally supportive of this notion. To date, however, little is known regarding the neuropsychology of depression as it may pertain to children; in particular, the possibility of functional motor asymmetry within this population has yet to be explored.


METHODS
Participants were asked to squeeze a hand dynamometer four times successively with each hand. The order of hand presentation was counterbalanced, and the dependent measure was in kilograms.


RESULTS
As hypothesized, depressed boys failed to demonstrate asymmetry for grip strength, although nondepressed boys exhibited right-hand grip strength. In addition, 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 strength longer across successive trials than did nondepressed boys.


CONCLUSIONS
The data are interpreted as consistent with current neuropsychological theories of emotion, particularly depression, and suggest that the functional motor asymmetries (i.e., failure to demonstrate asymmetric grip strength) observed in depressed adults are also present among depressed children. Implications for increased right hemisphere activation, decreased left hemisphere activation, or a combination of both are discussed.
Emerson
C S
CS
Department of Psychology, Virginia Polytechnic Institute and State University, Blacksburg 24061, USA.
Harrison
D W
DW
Everhart
D E
DE
Williamson
J B
JB
D001921:Brain / Q000503:physiopathology; D002648:Child; D003865:Major Depressive Disorder / Q000523:psychology*; D007839:Functional Laterality / Q000502:physiology; D018737:Hand Strength / Q000502:physiology*; D006801:Humans; D008297:Male; D011596:Psychomotor Disorders / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology*; D012720:Severity of Illness Index