The aging hand

Age-related and sex-related differences in hand and pinch grip strength in adults

The purpose of the study was to quantify age-related changes in hand grip strength and three types of pinch grip strength (key pinch, tip pinch, and palmar pinch) among male and female participants. The study included 199 healthy participants (100 females, 99 males) aged 20-79 years, who were divided into four age groups. The Baseline Hydraulic Hand Dynamometer and Baseline Hydraulic Pinch Gauge were used according to the standard procedures. For both the dominant and the nondominant hands, statistically significant differences between males and females, and between the age groups, were found using the analysis of variance. Mean hand and pinch grip strength were generally higher for the dominant hand and in males. The highest values of hand and pinch grip strength were found for males in the age group 35-49 years, and for females in age groups 20-34 and 35-49 years. Regardless of sex, the age group 65-79 years obtained the lowest values for all strength measures. The post-hoc tests showed significant differences between this and the other age groups in the majority of measures. Fewer differences were found between the younger groups. All strength measures correlated negatively with age (r = -0.29 to -0.41; P<0.01). In conclusion, these results show age-related changes in hand and pinch grip strength of the dominant and nondominant hands among male and female participants. Normative values according to the age groups are presented.

Cold-induced vasoconstriction at forearm and hand skin sites: the effect of age

During mild cold exposure, elderly are at risk of hypothermia. In humans, glabrous skin at the hands is well adapted as a heat exchanger. Evidence exists that elderly show equal vasoconstriction due to local cooling at the ventral forearm, yet no age effects on vasoconstriction at hand skin have been studied. Here, we tested the hypotheses that at hand sites (a) elderly show equal vasoconstriction due to local cooling and (b) elderly show reduced response to noradrenergic stimuli. Skin perfusion and mean arterial pressure were measured in 16 young adults (Y: 18–28 years) and 16 elderly (E: 68–78 years). To study the effect of local vasoconstriction mechanisms local sympathetic nerve terminals were blocked by bretylium (BR). Baseline local skin temperature was clamped at 33°C. Next, local temperature was reduced to 24°C. After 15 min of local cooling, noradrenalin (NA) was administered to study the effect of neural vasoconstriction mechanisms. No significant age effect was observed in vasoconstriction due to local cooling at BR sites. After NA, vasoconstriction at the forearm showed a significant age effect; however, no significant age effect was found at the hand sites. [Change in CVC (% from baseline): Forearm Y: −76 ± 3 vs. E: −60 ± 5 (P < 0.01), dorsal hand Y: −74 ± 4 vs. E: −72 ± 4 (n.s.), ventral hand Y: −80 ± 7 vs. E: −70 ± 11 (n.s.)]. In conclusion, in contrast to results from the ventral forearm, elderly did not show a blunted response to local cooling and noradrenalin at hand skin sites. This indicates that at hand skin the noradrenergic mechanism of vasoconstriction is maintained with age.

Hand osteoarthritis and pinch grip strength among middle-aged female dentists and teachers

OBJECTIVES

Among female dentists and teachers, we investigated the relationship of pinch grip strength with radiographic hand osteoarthritis (OA) and hand joint pain.

MATERIALS AND METHODS

We studied 295 female dentists and 248 female teachers aged 45-63 years for pinch grip strength using the Martin Vigorimeter. Hand radiographs were examined for the presence of OA in the wrist and each joint of the first, second, and third fingers. Joint pain and tasks with high hand loading during leisure were assessed by questionnaire. Glove size was used as proxy for hand size.

RESULTS

Symptomatic hand OA (jointwise co-occurrence of radiological findings and pain) increased the risk of low pinch grip strength in both hands, with an odds ratio (OR) of 3.3 (95% CI 1.8-6.2) for the right and 2.0 (95% CI 1.1-3.8) for the left hand, allowing for age, occupation, body mass index (BMI), hand size, and hand-loading leisure-time activity. The occurrence of findings and pain in non-corresponding joints was also associated with pinch grip strength in the right hand, but not in the left. Having only radiographic findings or pain was not associated with pinch grip strength.

CONCLUSIONS

Our findings support the view that hand function is related to the severity of hand OA.

Strength and Coordination Training Are Both Effective in Reducing the Postural Tremor Amplitude of Older Adults

The current study investigated the effect of 2 different types of unilateral resistance training on the postural tremor output of 19 neurologically healthy men age 70–80 yr. The strength- (n= 7) and coordination-training (n= 7) groups trained twice a week for 6 wk, performing dumbbell biceps curls, wrist flexions, and wrist extensions, while the control group (n= 5) maintained their normal activities. Changes in index-finger tremor (RMS amplitude, peak, and proportional power) and upper limb muscle coactivation were assessed during 4 postural conditions that were performed separately with the trained and untrained limbs. The 2 training groups experienced significantly greater reductions in mean RMS tremor amplitude, peak, and proportional tremor power 8–12 Hz and upper limb muscle coactivation, as well as greater increases in strength, than the control group. These results further demonstrate the benefits of resistance training for improving function in older adults.

Assessment of motor function of the hand in aged rhesus monkeys

In the elderly, intact motor functions of the upper extremity are critical for the completion of activities of daily living. Many studies have provided insight into age-related changes in motor function. However, the precise nature and extent of motor impairments of the upper extremity remains unclear. In the current study we have modified two tasks to assess hand/digit function in both young and aged rhesus monkeys. We tested monkeys from 9 to 26 years of age on these tasks to determine the level of fine motor performance across the adult age range. Compared to young monkeys (9-12 years of age), aged monkeys (15-26 years of age) were mildly impaired on fine motor control of the digits. These findings are consistent with previous studies that have found age-related impairment in fine motor function. However, the magnitude and extent of impairment in the current study does differ from previous findings and is likely due to methodological differences in the degree of task complexity.

Effects of age and gender on the movement workspace of the trapeziometacarpal joint

While researchers have suggested that joint mobility would probably be affected by age and gender, research findings often present discrepancies. Little research has been performed on the factors which effect mobility of the trapeziometacarpal (TMC) joint. The purpose of this study was to address the effects of age and gender on the ranges of motion of the normal TMC joint. Eighty normal subjects divided into four age groups participated in this study. The TMC joint motions were recorded using an electromagnetic tracking system. In order to achieve a maximal range of TMC joint motion which was defined as the maximal workspace, each subject was asked to perform actively maximal circumduction, flexion-extension, and abduction-adduction of the TMC joint. Numerical and statistical methods were used to compute the TMC workspace and to detect significant differences. A workspace-to-length ratio was determined as an index to examine the effects of the age and gender on the joint mobility. The results demonstrated that age and gender had significant influences on the TMC workspace among the groups studied. The understanding of TMC joint mobility under different age and gender conditions is achieved through this study. The findings can be used to report clinical measures in the determination of the extent of impairment of osteoarthritis as well as the outcomes between pre- and post-surgical (or non-surgical) interventions.

Variable stimulation patterns for poststroke hemiplegia

Neuromuscular electrical stimulation can improve motor function in those affected by paralysis, but its use is limited by a high rate of muscular fatigue. Variable stimulation patterns have been examined in young adults with and without spinal cord injury, but much less investigation has been devoted to studying the effects of variable stimulation patterns administered to older adults or those paralyzed by stroke. Significant changes occur in the neuromuscular system with age that may affect the response to variable stimulation patterns. We administered three, 3-min intermittent stimulation patterns to the median nerves of 10 individuals with hemiplegia from stroke and 10 age-matched able-bodied adults: (1) constant 20 HZ, (2) a pattern that began at 20 HZ and progressively increased to 40 HZ in the latter half of the task, and (3) a 20-HZ pattern that switched to a 20-HZ doublet pattern after 90 s. In the able-bodied group the doublet pattern produced significantly higher force time integrals (FTI) (1409.72 +/- 3.15 N s) than the 20-40-HZ pattern (1067.46 +/- 1.15 N s) or the 20-HZ pattern (831 +/- 1.87 N s). In the poststroke individuals the doublet pattern also produced the highest FTI (724.04 +/- 2.02 N s), and there was no significant difference between the 20-40-HZ (636.42 +/- 1.65 N s) and 20-HZ (583.64 +/- 3.02 N s) patterns. These results indicate that protocols that incorporate doublets in the later stages of fatigue are effective in older adults and in older adults with paralysis from stroke.

Restricted active range of motion at the elbow, forearm, wrist, or fingers decreases hand function

The purpose of this study was to investigate how restricting active range of motion (AROM) at various upper extremity segments influenced hand function in younger and older populations. Eighteen younger (27+/-4yr) and 15 older subjects (67+/-6yr) participated. A repeated-measures study design was used with six test conditions: one condition without AROM restrictions and five conditions with AROM restrictions (shoulder, elbow, forearm, wrist, fingers). AROM was restricted using customized braces. Hand function was measured using total time to complete the Jebsen-Taylor Test of Hand Function. We found that the older group took longer than the younger group to complete the Jebsen, and that restricting AROM at the elbow, forearm, wrist, or fingers resulted in decreased hand function for both groups. Because restricted AROM is a consequence of a variety of diseases and conditions, it is important to know how restricted AROM at multiple upper extremity segments affects hand function.

The effects of strength training on finger strength and hand dexterity in healthy elderly individuals

We investigated the effect of 6 wk of strength training on maximal pressing (MVC) force, indexes of finger individuation (enslaving), and performance in accurate force production tests and in functional hand tests in healthy, physically fit, elderly individuals. Twelve participants (average age 76 yr) exercised with both hands. One of the hands exercised by pressing with the proximal phalanges (targeting mainly intrinsic hand muscles), whereas the other hand exercised by pressing with the finger tips (targeting mainly extrinsic hand muscles). Training led to higher MVC forces, higher enslaving indexes, and improved performance on the pegboard grooved test. Changes in an index of multi-finger force stabilizing synergy showed a significant correlation with changes in the index of force variability in the accurate force production test. Strong transfer effects were seen to the site that did not perform strength training exercise within each hand. Effects of exercise at the proximal site were somewhat stronger compared with those of exercise at the finger tips, although the differences did not reach significance level. Control tests showed that repetitive testing by itself did not significantly change the maximal finger force and enslaving. The results suggest that strength training is an effective way to improve finger strength. It can also lead to changes in finger interaction and in performance of accurate force production tasks. Adaptations at a neural level are likely to mediate the observed effects. Overall, the data suggest that strength training can also improve the hand function of less healthy elderly subjects.

Changes in Hand Function with Age and Normative Unimpaired Scores when Measured with the Southampton Hand Assessment Procedure

Assessment of limitations in hand function due to impairment is commonplace in clinical practice and clinical research. When assessing impairment, it is useful to have an understanding of what comparative results an aged-match unimpaired participant population would generate and how the natural effects of an increase in age have on these results. Using the Southampton Hand Assessment Procedure (SHAP), this study assessed dominant hand function of 95 unimpaired participants between the ages of 18–75 years. The results extended available data from previous research and showed that the average SHAP score was 98 (± 3.3). The results indicate that there is a natural decline in hand function after the age of 65 years (p <0.001), which concurs with previously published studies using other assessments.

Relevance of race and ethnicity for self-reported functional limitation

It is unclear whether older adults of different race or ethnicity vary in the ways they perceive functional limitations. Variation in such self-reports may be relevant clinically, because many diagnoses (and subsequent care) depend on self-reported disability. To examine this question, self-reported hand function was compared with performance-based assessment of strength (hand dynamometer) and dexterity (Moberg Pick-Up Test) in white (n=102), African-American (n=67), and Hispanic (n=196) elderly people. Participants were Medicare beneficiaries from northern Manhattan, New York City, aged 70 and older. In adjusted analyses, self-reported hand function was associated with weaker grip strength in African-American and Hispanic participants but not in white participants. Self-reported difficulty with hand function was associated with poorer dexterity in all three groups. Similar results were observed in the subsample of participants with arthritis. These results suggest that culture or socioenvironmental differences associated with culture may influence reports of functional limitation.

Levodopa improves skilled hand functions in the elderly

The endogenous dopamine system is a potent modulator of motor function and learning. Previous studies have demonstrated that, in the elderly, age-related degeneration of the nigrostriatal dopamine system may contribute to deficits in execution of skilled motor functions. The present double-blind, randomized cross-over study examined whether pharmacologically replenishing dopamine improves the execution of complex motor tasks. Twenty healthy young and 20 healthy elderly subjects were studied in two different sessions: (i) after three doses of levodopa (each 100 mg levodopa plus 25 mg carbidopa) and (ii) after three doses of placebo. For each session, subjects completed a functional motor test that reflects hand activities of daily living (Jebsen-Taylor test). In the elderly, but not in the young, Jebsen-Taylor test performance improved significantly (4%) with levodopa compared with placebo, particularly for fine motor functions. Attention to the task, level of fatigue, and positive and negative feelings were similar between sessions. These results demonstrate that increasing the dopaminergic drive pharmacologically may be helpful when the motor system is challenged in the ageing process.

An overview of dual sensory impairment in older adults: perspectives for rehabilitation

Dual sensory impairment (DSI) refers to the presence of both hearing loss and vision loss. The occurrence of DSI is particularly prevalent among the aging population, with studies showing between 9% and 21% of adults older than 70 years having some degree of DSI. Despite this, there is little direction regarding recommended clinical practice and rehabilitation of individuals with DSI. It is assumed that the problems encountered by individuals with DSI are considerably greater than the effects of vision impairment or hearing impairment alone, because when these two sensory impairments are combined, the individual is seriously deprived of compensatory strategies that make use of the nonimpaired sense. In this article, the literature available regarding DSI is summarized, and research needs regarding rehabilitation strategies are outlined and discussed. Simple suggestions for addressing DSI are provided that use available tools and technology.

Strength training improves the tri-digit finger-pinch force control of older adults

OBJECTIVE

To investigate the effect of unilateral upper-limb strength training on the finger-pinch force control of older men.

DESIGN

Pretest and post-test 6-week intervention study.

SETTING

Exercise science research laboratory.

PARTICIPANTS

Eleven neurologically fit older men (age range, 70-80y).

INTERVENTION

The strength training group (n=7) trained twice a week for 6 weeks, performing dumbbell bicep curls, wrist flexions, and wrists extensions, while the control group subjects (n=4) maintained their normal activities.

MAIN OUTCOME MEASURES

Changes in force variability, targeting error, peak power frequency, proportional power, sample entropy, digit force sharing, and coupling relations were assessed during a series of finger-pinch tasks. These tasks involved maintaining a constant or sinusoidal force output at 20% and 40% of each subject's maximum voluntary contraction. All participants performed the finger-pinch tasks with both the preferred and nonpreferred limbs.

RESULTS

Analysis of covariance for between-group change scores indicated that the strength training group (trained limb) experienced significantly greater reductions in finger-pinch force variability and targeting error, as well as significantly greater increases in finger-pinch force, sample entropy, bicep curl, and wrist flexion strength than did the control group.

CONCLUSIONS

A nonspecific upper-limb strength-training program may improve the finger-pinch force control of older men.

Risk of upper limb complaints due to computer use in older persons: a randomized study

Background

We studied whether the twelve-month use of a standard computer would induce complaints of upper limb pain or functional limitations in older novice computer users.

Methods

Participants between 64 and 76 of age were randomly assigned to an Intervention group (n = 62), whose members received a personal computer and fast Internet access at their homes, or a No Intervention control group (n = 61), whose members refrained from computer use during the twelve month study period.

Results

Difference scores between baseline and twelve months assessments on both complaint (SFS) and functional health scales (SF-36) did not differ between groups (all p > .05).

Conclusion

Prolonged, self-paced use of a standard computer interface does not put older persons at a risk of upper limb complaints or reduce functional health in older adults.

A Randomized Controlled Trial of Modified Constraint-Induced Movement Therapy for Elderly Stroke Survivors: Changes in Motor Impairment, Daily Functioning, and Quality of Life

OBJECTIVE

To examine the benefits of modified constraint-induced movement therapy (mCIMT) on motor function, daily function, and health-related quality of life (HRQOL) in elderly stroke survivors.

DESIGN

Two-group randomized controlled trial, with pretreatment and posttreatment measures.

SETTING

Rehabilitation clinics.

PARTICIPANTS

Twenty-six elderly stroke patients (mean age, 72 y) with 0.5 to 31 months postonset of a first-ever cerebrovascular accident.

INTERVENTIONS

Twenty-six patients received either mCIMT (restraint of the unaffected limb combined with intensive training of the affected limb) or traditional rehabilitation for a period of 3 weeks.

MAIN OUTCOME MEASURES

Outcome measures included the Fugl-Meyer Assessment (FMA), FIM instrument, Motor Activity Log (MAL), and Stroke Impact Scale (SIS). The FMA evaluated the severity of motor impairment; the FIM instrument and MAL reported daily function; and the SIS detected HRQOL.

RESULTS

The mCIMT group exhibited significantly greater improvements in motor function, daily function, and the physical domain of HRQOL than the traditional rehabilitation group. Patients in the mCIMT group perceived significantly greater percent of recovery after treatment than patients in the traditional rehabilitation group.

CONCLUSIONS

These findings suggest mCIMT is a promising intervention for improving motor function, daily function, and physical aspects of HRQOL in elderly patients with stroke. The mCIMT was well tolerated by the elderly patients even though it is a rigorous training program.

The effect of radiological hand osteoarthritis on hand function

The aim of the study was to investigate the effect of osteoarthritis (OA) on hand function in elderly patients. One hundred elderly patients with a mean age of 68.50 +/- 6.37 years (87 women, 13 men) were enrolled to the study. Radiological hand OA was defined as the presence of Kellgren-Lawrence (K-L) grade > or = 2. Grip strength, and lateral, tip, and three-fingered pinches were measured. Hand function was assessed by Dreiser's functional index. Subjective hand disability was assessed by the hand disability index of Stanford Health Assessment Questionnaire (HAQ) and by self-reported functional limitation. Coordination was evaluated by testing for rapid alternating movement (RAM) and fine finger movement (FFM). The Jebsen test of hand function was used to determine functional hand use. Forty patients had K-L > or = 2 radiological hand OA, and 60 patients had K-L = 0 and 1 and were accepted as the control group. In the clinical examination, 54 patients had Heberden's nodules and 35 had Bouchard's nodules. Self-reported functional limitation tests (activities like carrying a bundle and handling or fingering small objects) were significantly worse in patients with radiographic hand OA, and also, non-dominant hand RAM was slower in the same group. According to the evaluation of the radiologic grades of OA, grades 3-4 OA had higher scores than the control and grade 2 OA group. Our results suggest that there is a lack of association between radiological hand OA and Jebsen test and objective hand functions like grip and pinch strength, but the patients with radiological hand OA have restrictions in the self-reported functional limitation test. The presence of tenderness, pain, and Heberden's and Bouchard's nodules had a negative effect on hand functions. Dreiser's functional index and the hand disability index of HAQ were found as related parameters with the radiological grade of OA.

Age-related attenuation of dominant hand superiority

BACKGROUND

The decline of motor performance of the human hand-arm system with age is well-documented. While dominant hand performance is superior to that of the non-dominant hand in young individuals, little is known of possible age-related changes in hand dominance. We investigated age-related alterations of hand dominance in 20 to 90 year old subjects. All subjects were unambiguously right-handed according to the Edinburgh Handedness Inventory. In Experiment 1, motor performance for aiming, postural tremor, precision of arm-hand movement, speed of arm-hand movement, and wrist-finger speed tasks were tested. In Experiment 2, accelerometer-sensors were used to obtain objective records of hand use in everyday activities.

PRINCIPAL FINDINGS

Our data confirm previous findings of a general task-dependent decline in motor performance with age. Analysis of the relationship between right/left-hand performances using a laterality index showed a loss of right hand dominance with advancing age. The clear right-hand advantage present at younger ages changed to a more balanced performance in advanced age. This shift was due to a more pronounced age-related decline of right hand performance. Accelerometer-sensor measurements supported these findings by demonstrating that the frequency of hand use also shifted from a clear right hand preference in young adults to a more balanced usage of both hands in old age. Despite these age-related changes in the relative level of performance in defined motor tasks and in the frequency of hand use, elderly subjects continued to rate themselves as unambiguous right-handers.

CONCLUSION

The discrepancy between hand-specific practical performance in controlled motor tests as well as under everyday conditions and the results of questionnaires concerning hand use and hand dominance suggests that most elderly subjects are unaware of the changes in hand dominance that occur over their lifespan, i.e., a shift to ambidexterity.

Assessing the handwriting process in healthy elderly persons using a computerized system

BACKGROUND AND AIMS

Despite the importance of handwriting in everyday life, virtually no literature can be found documenting the extent and range of everyday handwriting performance and ability among healthy elderly persons. The aim of this pilot study was to examine the kinematic characteristics of the handwriting process of healthy elderly persons and its correlates.

METHODS

Fifty-three healthy participants (aged 60 to 94) living in the community, performed five functional writing tasks using a computerized system which documented the handwriting process.

RESULTS

In air time (i.e., the time of non-writing while writing) accounted for approximately half to two-thirds of total writing time. Higher age was consistently associated with longer on paper and in air time, as well as with lower speed and lower pressure.

CONCLUSIONS

The results of this pilot study indicate that kinematic analysis of handwriting provides important information about the handwriting process among elderly people.

Flexor tendon rupture 55 years following a wrist laceration

Flexor tendon rupture at the wrist or palm is rare. We present a case of index flexor digitorum profundus rupture at the level of the wrist associated with the site of a laceration 55 years earlier. Associated pathology included a large neuroma-in-continuity of the median nerve and adhesions involving the flexor digitorum superficialis tendons. The rupture was treated by tenodesis to the relatively unaffected flexor digitorum profundus to the adjacent long finger.

Age-related differences in inter-digit coupling during finger pinching

The present study was designed to examine the finger-pinch force control, digit force sharing and digit coupling relations of 13 young and 14 older adults. Subjects performed four isometric tri-digit finger-pinch force production conditions reflecting all combinations of mean force level (20 and 40% MVC) and target shape (constant and sinusoidal). Older adults had significantly reduced force control, as indicated by their greater levels of absolute and relative force variability and targeting error than young adults. The age-related loss of relative force control was more pronounced at low (20% MVC) than high (40% MVC) forces, and to a lesser extent, in sinusoidal than constant force conditions. Older adults had significantly greater peak and proportional power below 1.5 Hz than young adults, with this especially pronounced in constant force conditions. Digit force sharing results indicated that the index finger's contribution to total force was increased and the middle finger's contribution reduced in older than young adults. The results of the cross-correlation analyses revealed that older subjects had a significantly reduced level of coupling between the middle finger and the target force, thumb force and EMG signals, with longer time lags in comparison to young adults. These differences in force sharing and middle finger force coupling were more pronounced in sinusoidal than constant force conditions. Overall, these results suggest that the older adults' reduced force control reflected age-related differences in the sharing and coupling of the finger forces. The results also highlighted that tasks of this nature display a degree of task-dependency, with these overall differences in digit force output and coupling not consistently observed across all force conditions.

Age-related changes in pressure pain threshold, grip strength and touch pressure threshold in upper extremities of older adults

BACKGROUND AND AIMS

Hand function weakens with age in both men and women, especially after the age of 65. As the number of older people increases, more older adults may have sensorimotor impairment, which affects upper extremity (UE) performance and thus independence in the activities of daily life. The purpose of this study was to detect and evaluate the impact of age on pressure pain threshold (PPT), touch/pressure threshold and grip strength in the decades after the age of 60.

METHODS

The study was carried out with the participation of older adults living in the Izmir Geriatric Centre. Older adults were subdivided into three age groups and 128 subjects (47 male, 81 female) were selected systematically as one out of every three individuals in each group (group 1: 60 to 69; group 2: 70 to 79; group 3: 80 or over). Touch/pressure threshold test, pressure pain threshold (PPT) test and grip strength measurement were performed on dominant and non-dominant hands.

RESULTS

It was found out that touch/pressure thresholds increased with age, but the change was not statistically significant between the three age groups. PPT and grip strength of dominant and non-dominant hands decreased from groups 1 to 3, but analysis indicated that these declines were not statistically significant.

CONCLUSIONS

Despite the fact that age-related sensorimotor changes are not statistically significant, a reduction is seen in sensorimotor parameters after the age of 60.

Arthritic pain, aging, and psychomotor decline in people with HIV

Arthritic pain and subsequent immobility are common in people with Human Immunodeficiency Virus (HIV) and in persons of older ages. It is hypothesized that such pain may contribute to psychomotor impairment commonly observed with HIV and aging. Empirical evaluation of this hypothesis among older persons with HIV and consideration of treatment should be undertaken.

Memories that last in old age: motor skill learning and memory preservation

Using an automated test panel, age-associated declines in learning, remembering and performing a novel visuomotor task were assessed in 497 normal adults ranging from 18 to 95 years old. As predicted, task performance times slowed with increasing age in the cross-sectional portion of the study. However in the subsequent longitudinal study, while motor learning was significantly slower in adults over 62 years old, motor memory was pristinely preserved in normal adults from 18 to 95 years old. When tested 2 years after the first training session and without intervening rehearsal, mean performance times were retained and continued to improve by 10% in young adults and 13% in aged adults, reflecting long lasting preservation of motor memories. While the maximum lifetime of an unpracticed, novel motor memory in humans is not known, the present study suggests that new motor memories can be retained for at least 2 years without rehearsal in normal aged adults. This age-resistant component of motor memory stands in contrast to the well-known decrements in other motor and cognitive processes with human aging.

Sex differences in age-related motor slowing in the rhesus monkey: behavioral and neuroimaging data

The nigrostriatal system is critical for fine motor function and its deterioration during aging is thought to underlie the decline in fine manual ability of old persons. Because estrogen has a neuroprotective effect on this system, one might expect women's motor function to be less vulnerable to the detrimental effects of aging than that of men. We examined this hypothesis in the rhesus monkey, which has been established as an excellent model of human age-related motor impairment. We tested 28 young and old rhesus monkeys of both sexes in a task involving the retrieval of a Life Saver candy from rods of different complexity to determine whether fine motor ability (1) is sexually dimorphic, (2) declines with age and (3) declines differently in males and females. In addition, we measured the whole brain volume, the volumes of the caudate, putamen, hippocampal formation and the area of the corpus callosum in a subset of the monkeys (n=15) for which magnetic resonance images of the brain were available. All monkeys performed similarly in the test with the simplest rod. In the test with complex rods; however, age-related slowing of motor function was evident in males, but not in females. Age-related decreases in the normalized caudate and putamen volumes were similar in males and in females. In addition, motor speed was not significantly correlated to any of the neuroanatomical measures under study. Further studies will be necessary to uncover the neurohormonal bases of the differential age-related motor decline between males and females.

Prevalence and determinants of one month hand pain and hand related disability in the elderly (Rotterdam study)

OBJECTIVE

To study the prevalence of hand pain and hand disability in an open population, and the contribution of their potential determinants.

METHODS

Baseline data were used from 7983 participants in the Rotterdam study (a population based study in people aged > or =55 years). A home interview was used to determine the presence of hand pain during the previous month, rheumatoid arthritis, osteoarthritis in any joint, diabetes, stroke, thyroid disease, neck/shoulder pain, gout, history of fracture in the past five years, and Parkinson's disease, as well as age, sex, and occupation. Hand disability was defined as the mean score of eight questions related to hand function. Body mass index was measured and hand x rays were taken.

RESULTS

The one month period prevalence of hand pain was 16.9%. The prevalence of hand disability was 13.6%. In univariate analysis for hand pain, rheumatoid arthritis had the highest explained variance (R(2)) and odds ratio. For hand disability, aging showed the highest explained variance and Parkinson's disease had the highest odds ratio. All determinants together showed an explained variance of 19.8% for hand pain and 25.2% for hand disability. In multivariate analysis, positive radiographic hand osteoarthritis was a poor explanation for hand pain (R(2) = 0.5%) or hand disability (R(2) = 0).

CONCLUSIONS

The contribution of available potential determinants in this study was about 20% for hand pain and 25% for hand disability in an unselected population of elderly people. Thus a greater part of hand pain/hand disability remains unexplained.

Precision grasps of children and young and old adults: individual differences in digit contact strategy, purchase pattern, and digit posture

The evolutionary origins and variations of the precision grip, in which an object is held between the thumb and other digits, are poorly understood. This is surprising because the neural basis of this grasp pattern, including the motor cortex and pyramidal tract have received extensive study. Most previous work has shown that features of an object to be grasped (external factors) determine grasp patterns. The objective of the present study was to investigate individual differences (central factors) in use of the pincer and other precision grips. The grasping patterns of male and female young adults, older adults and children were examined as they reached (with both left and right hand) for five small beads (3-16 mm diameter). Frame-by-frame analysis of grasping indicated a high degree of variability in digit contact strategies, purchase patterns and digit posture both within and between subjects. (1) The contact strategies consisted of five variations, depending on whether the thumb or the index finger dragged or stabilized the bead for grasping. (2) Purchase patterns consisted of seven different types of precision grips, involving the thumb and various combinations of other digits. (3) There were four variations stemming from the posture of the non-grasping digits. Grip patterns of the left and right hands were correlated in individual subjects, as were strategies used for different bead sizes. Females displayed slightly more variability in grasp patterns than did males, and digit width (obtained from photocopies of the subjects' hands) was weakly correlated with the grasp patterns used. Although it was expected that the pincer would be used for all objects, it was preferentially used for only the smallest object except for older adults who used the pincer grasp on most objects. The variability in digit contact strategies, purchase patterns, and posture of the non-grasping digits indicates that central factors (innate or learning-induced architecture of the left parietal cortex) make important contributions to the selection of a grasping pattern. These individual differences are discussed in relation to the neural control of grasping and its potential contribution to understanding the evolution, development, and pathology of the precision grip.

Factors related to postmenopausal muscle performance: a cross-sectional population-based study

The aim of the present study was to investigate cross-sectionally the association of postmenopausal muscle strength with simple performance tests. A random sample of 1,166 naturally postmenopausal women (born 1932-1941) was selected from the Kuopio Osteoporosis Risk Factor and Prevention (OSTPRE) study cohort. Grip and quadriceps strength were measured with strain gauge dynamometers and reported in both absolute values (KPa and kg) and per kilogram of body mass (N cm(-2) kg(-1) and N kg(-1)). In addition, two performance tests, 'ability to stand on one foot' and 'ability to squat down to touch the floor' were carried out. A five-category self-assessment of overall health ('very good', 'good', 'moderate', 'bad', and 'very bad') was obtained by postal questionnaire. The women that were able to stand on one foot and able to squat down to touch the floor had greater grip and quadriceps strength than their counterparts ( P<0.001 and P<0.03 in ANOVA, respectively). In addition, self-assessed health had a strong positive association with muscle strength in the grip and leg extensor muscles in ANOVA ( P<0.001 between 'very good' and 'moderate' or poorer state of health) and regression model ( P<0.001). Adjustment for age, duration of menopause, body mass, height, physical activity level, use of HRT, and number of diseases and medications did not change any of the main effects. Also, there were no differences in results between absolute measurement values and values reported per kilogram of body mass. According to the present study, a simple performance test may be useful in the prediction of postmenopausal muscle strength. Furthermore, self-assessed state of health is strongly associated with muscle strength in postmenopausal women.