Associations between handedness and executive function in upper-middle-aged people.

Many studies have investigated the relationship between handedness and executive functioning using behavioural measures, although the exact nature of this relationship remains unclear. In this study, the relationship between handedness and executive function was examined using the D-CAT (Digit Cancellation Test) performances of 76 left-handed (42 men and 34 women) and 76 age-matched right-handed (42 men and 34 women) healthy community dwellers. The mean age of the participants was 62.7 years (SD = 10.3). In addition, the visuospatial performance was also examined using the Money Road Test. Left-handed people of both sexes showed a poor performance on both tests than right-handed people. Right-handed people showed typical laterality with regard to the relationship between the sex and facets of cognition, whereas left-handed people showed no clear laterality difference. Men showed no handedness difference in the executive function and women showed no handedness difference in the case of the visuospatial function test. The possible contributions of the three different executive functioning components, information updating, shifting, and inhibition, to this handedness difference in the upper-middle-aged people, are discussed.