Sex and eyedness in a sample of Turkish high school students

Significant gender-specific difference in brain lateralization of schizophrenia patients assessed by new combined foot dominance scale

Objective

Reduced hemispheric asymmetry has been identified as a potential risk factor for schizophrenia, characterized by diminished brain lateralization and a lack of dominance in the left hemisphere. Moreover, there is growing evidence of disrupted connectivity between various cortical regions. This study aimed to investigate gender differences in left-footedness as a potential biological marker for neuronal dysontogenesis in individuals with schizophrenia and control subjects.

Materials and methods

A New Combined Foot Dominance Scale (14 foot tests), comprising a Modified Chapman & Chapman Subscale (10 foot tests) and a Complex Tasks Subscale (four foot tests) was administered as performance tasks in 180 subjects [98 schizophrenia patients with mean age 34.45 years (SD = 15.67, range 23-79) for men and 42.20 years (SD = 11.38, range 21-63) for women and 82 controls with a mean age 34.70 years (SD = 16,82, range 18-79) for men and 44.50 years (SD = 10.73, range 23-67)]. As our data are not continuous and lacks normal distribution, the non-parametric Mann-Whitney test was used for comparing categorical data.

Results

The mean left-footedness, as assessed by the New Combined Foot Dominance Scale, is significantly higher in individuals with schizophrenia compared to control subjects. Our findings from inter-gender comparisons reveal that female schizophrenia patients exhibit a significantly greater average left-footedness than female control subjects, while in males no such a statistical significant difference is detected.

Conclusion

Left foot dominance is higher in patients with schizophrenia than in control subjects and women contribute significantly more to this difference.

Lateralidade manual, ocular e dos membros inferiores e sua relação com déficit de organização espacial em escolares

Este estudo teve por objetivos: 1) verificar se existe associação entre lateralidade manual, ocular e dos membros inferiores e déficit de organização espacial em escolares; 2) categorizar as variações de lateralidade nesta população. A amostra foi constituída de 400 crianças na faixa etária de 6 a 10 anos de escolas públicas e privadas da cidade de João Pessoa (PB). A lateralidade e a organização espacial foram avaliadas, respectivamente, por meio do Harris Test of Lateral Dominance e da Bateria de Piaget-Head. Os resultados evidenciaram 23 tipos de lateralidade mão-olho-pé, observando-se maior percentual (48,75%) de destralidade completa (dominância manual, ocular e dos membros inferiores direita). Houve associação significativa (p<0,05) entre sinistralidade completa e déficit de organização espacial. Os resultados atentam para a importância de se inserirem no cotidiano escolar programas de estimulação motora voltados à lateralidade e à organização espacial das crianças, como forma de prevenir distorções no seu processo de aprendizagem.

Differences by Sex and Handedness in Right and Left Femur Bone Mineral Densities

Left-handedness was reported to be a risk factor for accident-related injuries, head injuries, traumatic brain injuries, sport-related injuries, and bone breaks and fractures. As decreased bone mineral density is a good marker of bone fractures, the femoral bone mineral densities of normal left-handed university students were compared with those of right-handed students. Hand preference of 66 men and 47 women was assessed using the Edinburgh Handedness Inventory. Measures of bone mineral density with a Hologic QDR-4500W (S/N 48403) densitometer showed bone mineral densities of both right and left proximal femur regions were higher in right-handed than in left-handed students. These results are consistent with the claim that left-handed participants had higher trauma and injury risk. Also, these results may explain the sex-related differences by handedness for susceptibility in accident-related injuries such as bone fractures.