In the present study, we attempted to find predictors of the response to antiepileptic treatment with the adjustment for individual constitutional characteristics of patients including the profile of hemispheric asymmetry (right- and left handedness), premorbid personality, predisposition to affective and other mental disorders. We administered a large battery of tests (MMSE, HAM-A, HAM-D, TAS-26 and others). Treatment efficacy was assessed by the degree of seizure frequency reduction and remission duration. Two groups of patients, with 100% reduction of seizures after 12 months of treatment with antiepileptic drugs and with the absence of reduction of seizures, were singled out. It has been shown that left-handedness, cognitive impairment in right-handers, alexithymia and affective disorders in left-handers predict poor treatment efficacy.