About this Research Topic
By 2050, 20% of the US population will be 65 years and older in age. Many of these individuals demonstrate an impaired ability to perform activities of daily living (ADLs) that require fine manual skills such as inserting coins in a slot, buttoning-unbuttoning, and inserting a key into a lock. As these impairments worsen there is an increased likelihood of requiring assistance in daily tasks. With an expected increase in the size of the aging population in coming years, age-related motor impairment will bring significant financial burden to the country. Thus, there is a need to develop measures to ameliorate the impairment in manual dexterity, and thus reduce or avoid disability in older adults. This requires a better understanding of the mechanisms underlying impairment in manual behavior with age.
Aging affects various levels of the sensorimotor system involved in hand functions. Senile brain demonstrates reduction in gray matter volume in pre-frontal cortex, cerebellum, primary and secondary sensorimotor cortices, alterations in white matter tracts, and reduction in neurotransmitters such as acetylcholine and dopamine. Furthermore, older adults activate wider brain networks during performance of a motor task with evidence favoring engagement of compensatory mechanisms. Aging also impacts peripheral structures such as restructuring of motor units, slowing in nerve conduction velocity, sarcopenia, and reduction in skin mechanoreceptors for sensing. These age-related changes have been associated with slowing on motor tasks.
Older adults often become less skilled in performing manual tasks. Dexterous manipulation requires fine control of finger forces. Evidence from laboratory tasks, some of which were functional (like ADLs), suggests that older adults demonstrate impaired ability to control the magnitude and direction of force application, resulting in unwanted torque on the object that can alter object orientation, and show reduced steadiness in the control of finger forces. Age-related changes at any level of the sensorimotor system can impair fine control of finger forces. More importantly, the contribution of poor finger force control to the decline in dexterous manipulation is beyond the commonly reported age-related ubiquitous behavioral slowing. Although reduced strength is a common report, it is unclear if reduced hand strength is a source of disability and dependency, particularly for dexterous manipulation. Lastly, aging also impairs the ability to perform motor tasks with both hands.
As aging cannot be arrested, there is a need to investigate means for slowing the inexorable decline in manual behavior. Several interventional paradigms such as motor practice, strength training, exercise, and peripheral and cortical electrical stimulation have shown promise in improving older adults’ ability to perform motor tasks. Better understanding of neural mechanisms underlying impaired manual behavior with aging will help us to define targets for effective rehabilitation of hand functions.
This Research Topic is aimed at facilitating discussion on the current knowledge about the effects of aging on hand functions and underlying neural correlates, and the availability of rehabilitation measures to improve hand functions in elderly population.
Important Note: All contributions to this Research Topic must be within the scope of the section and journal to which they are submitted, as defined in their mission statements. Frontiers reserves the right to guide an out-of-scope manuscript to a more suitable section or journal at any stage of peer review.