Indians are less sensitive to touch

March 26, 2008
By Syed Akbar
Hyderabad, March 25: Indians are less sensitive to touch than other populations in the world.
The touch sensibility thresholds recorded in a large group of Indians, particularly from Hyderabad, are higher than that reported from Westerners. A research study conducted by the clinical and epidemiology division of Blue Peter Research Centre, LEPRA Society, Hyderabad, showed that the touch threshold values of Indians were, however, closer to reports from Asia.
Indians show a tendency to increased loss of touch sensibility as they age. "Touch sensibility testing is a cost-effective, psycho-physical measure of peripheral nerve function and impairment. However, there is limited information regarding the natural variability in touch sensibility across different populations and different age groups. This prompted us to take up the study," says senior scientist Dr Indira Nath, who led the research.
Gender taken alone did not show a relationship with the level of sensory perception, she said adding that "of interest is our observation that gender contributed significantly when the subjects were stratified on the basis of age."
As part of the study as many as 568 healthy Indian volunteers without any clinical evidence of peripheral nerve disease were enrolled. Touch sensibility was evaluated bilaterally in palms, feet, and heels with target forces ranging from 0.008 to 300 grams per millimetre.
"No differences were observed between the right and the left limbs. The lowest target force detected ranged from 0.4 to 2 grams in the palms and 1.4 to 15 grams in the feet. These values showed further increase with age. Women compared with men had higher sensibility in the palms in most age groups. Touch sensibility thresholds recorded in a large group of Indians were higher than that reported in other populations," Dr Indira Nath said.
These findings have clinical implications for the diagnosis of early nerve
impairment in the elderly and in disease states drawing attention to geographic variations in touch sensation. Data was collected on 15,903 sites on the palms, feet, and heels of the subjects. In general, the palms showed the highest and the heels the lowest sensory perception with the feet showing intermediate values.
The scientists observed an interactive effect of age and gender. Palms of
females had
lower touch sensibility thresholds compared with the males in all the age groups. The higher tactile threshold seen in the feet compared with the palm may also be due to the thicker layer of keratin seen in plantar skin or due to ethnic factors and cultural habits of walking barefoot. The plantar surfaces showed more variations than the palms at individual sites, but this was not significant.
"We also found that the heel area showed the greatest intersite variation and was the least sensitive, perhaps due to its load-bearing functions. Paradoxically, the plantar surface of men appeared to be more sensitive than women in general. Whether this was due to greater access of men to footwear compared with women could not be confirmed definitively," she said.