Humans, known for their tactile nature, experience profound physiological effects from touch. When deprived of touch, the stress hormone cortisol rises, weakening immunity while elevating heart rate and blood pressure. Conversely, physical contact triggers a cascade of positive responses in the brain, including the release of natural opioids, oxytocin (the bonding hormone), dopamine, and serotonin, enhancing overall well-being.
While it’s commonly believed that aging diminishes our tactile acuity along with vision and hearing, recent findings bring hope to those fearing inevitable sensory decline. Published in Frontiers in Aging Neuroscience, the study reveals a surprising trend: deterioration in touch sensitivity occurs primarily in hairless skin regions, sparing areas with dense hair coverage.
Dr. Jean-Marc Aimonetti, from the Research Center in Psychology and Neurosciences in Marseille, France, and co-author of the study, highlights, “Touch sensitivity declines with age on the hands but remains robust on our hairy arms and cheeks, particularly sensitive to tactile stimuli.”
The research involved 96 left-handed female volunteers aged 20 to 75. Sensitivity tests were conducted on three areas: the hairless tip of the right index finger, and the right forearm and cheek, both naturally covered in fine hair. Participants, isolated in a quiet environment with eyes closed and noise-canceling headphones, underwent tactile assessments.
In one experiment, subjects ran their index fingers over plates with grooves of varying widths, detecting changes compared to a reference. Results indicated reduced sensitivity in spatial exploration with age, particularly pronounced in the index finger.
Another test employed monofilaments of calibrated forces, progressively decreased to measure touch detection thresholds. The index finger’s sensitivity threshold increased linearly with age, corroborating declining touch perception over time.
Unexpectedly, the cheek and forearm showed no significant decline in touch sensitivity across age groups. Even among the oldest participants, sensitivity thresholds remained stable, contrasting sharply with the observed decline in the index finger.
Dr. Rochelle Ackerley, co-author of the study, notes, “Affective touch, crucial for social bonding, is frequently received on hairy skin areas, which maintain sensitivity throughout life. This preservation underscores our social nature as humans.”
The researchers attribute this phenomenon to hair’s role in protecting and enhancing tactile sensitivity. Hair acts as a mechanical sensor, amplifying even subtle stimuli and shielding the skin from environmental factors.
“Hair serves multiple purposes beyond mere protection, aiding in sensory perception and environmental awareness,” explains Aimonetti. “Its presence in sensitive areas appears integral to maintaining tactile acuity.”
To preserve skin sensitivity, researchers suggest minimizing exposure to extreme thermal conditions and avoiding lifestyle habits detrimental to skin health, such as excessive alcohol consumption, smoking, sun exposure, and pollution.
These findings not only challenge conventional beliefs about age-related sensory decline but also underscore the complex interplay between tactile perception, hair, and aging. As research continues, understanding these mechanisms promises insights into enhancing quality of life and tactile experiences across the lifespan.
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