Relationship between age of menopause and cell-mediated immune hypersensitivity in right- and left-handed women

Lateralization of Squamous Cell Carcinomas in the Head-Neck Region

Earlier studies have shown the lateralization of several immune disorders, including herpes zoster infection and breast cancer. We investigated whether there is lateralization of squamous cell carcinomas in the head-neck region and a relation of handedness with this cancer. Analysis showed right-sided lateralization of head-heck cancers in right-handed patients and vice versa in left-handed ones and a higher rate of left-handedness in patients with squamous cell cancer. Associations among left-handedness, squamous cell carcinoma, and its lateralization may result from a genetic togetherness.

Impact of right-handedness on anaesthetic sensitivity, intra-operative awareness and postoperative mortality

Anatomical, neurological and behavioural research has suggested differences between the brains of right- and non-right-handed individuals, including differences in brain structure, electroencephalogram patterns, explicit memory and sleep architecture. Some studies have also found decreased longevity in left-handed individuals. We therefore aimed to determine whether handedness independently affects the relationship between volatile anaesthetic concentration and the bispectral index, the incidence of definite or possible intra-operative awareness with explicit recall, or postoperative mortality. We studied 5585 patients in this secondary analysis of data collected in a multicentre clinical trial. There were 4992 (89.4%) right-handed and 593 (10.6%) non-right-handed patients. Handedness was not associated with (a) an alteration in anaesthetic sensitivity in terms of the relationship between the bispectral index and volatile anaesthetic concentration (estimated effect on the regression relationship -0.52 parallel shift; 95% CI -1.27 to 0.23, p = 0.17); (b) the incidence of intra-operative awareness with 26/4992 (0.52%) right-handed vs 1/593 (0.17%) non-right-handed (difference = 0.35%; 95% CI -0.45 to 0.63%; p = 0.35); or (c) postoperative mortality rates (90-day relative risk for non-right-handedness 1.19, 95% CI 0.76-1.86; p = 0.45). Thus, no change in anaesthetic management is indicated for non-right-handed patients.

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.

The relationship between handedness and risk of multiple sclerosis

BACKGROUND

Left-handedness has been studied as a marker for in-utero exposure to sex steroid hormones, and an increased risk of autoimmune and immune disorders among left-handed individuals has been suggested.

OBJECTIVE

This study examines the relationship between hand preference and risk of multiple sclerosis, a presumed autoimmune disorder of unknown etiology.

METHODS

The study population comprised participants in the Nurses' Health Study, an ongoing prospective cohort study of 121,701 female nurses in the United States with followup from 1976 to 2002. The nurses were asked to report their natural hand preference (right, left, ambidextrous, forced to change).

RESULTS

During followup 210 incident cases with multiple sclerosis were confirmed. A 62% increased risk of multiple sclerosis was observed among women who were naturally left handed as compared to those who were naturally right handed (95% CI: 1.04-2.53).

CONCLUSIONS

This study suggests a modest increase in risk of multiple sclerosis among left-handed women. Further investigation of this relationship is suggested in other populations including both males and females. While the current results suggest that prenatal exposure to sex hormones may play a role in multiple sclerosis risk, direct examination of the relationship between in-utero hormone exposure and hand preference is necessary before any conclusions can be drawn.

Clinical importance of asymmetry and handedness differences in common carotid artery intima-media thickness

Earlier publications have reported that common carotid artery intima-media thickness (CCA-IMT) was lower on the right side than on the left side and that left-handed patients have a lower risk of sudden death of brain infarction. This study aimed to determine whether there is an asymmetry and the handedness related difference in CCA-IMT. Ultrasonographic examinations were performed with the use of Aplio US system. In total sample, male and female left-handers, CCA-IMT was greater on left side than on right side. In men, both right and left CCA-IMTs, but in women only right IMT, were lower in the left-handers than in the right-handers. Both right and left CCA-IMTs was positively correlated with age in men and in women. Handedness was a significant factor influencing CCA-IMT with adjustment for sex and age. It was greater on left side than on right side, especially in the left-handers. CCA-IMTs were lower in the left-handers than in the right-handers. These results suggest that hemodynamic stress and intimal damage was larger in the left carotid artery, which was larger in the right-handers compared to the left-handers.