Measuring hand sensory function and force control in older adults: Are current hand assessment tools enough?

Tryptophan-Kynurenine Pathway Activation and Cognition in Virally Suppressed Women With HIV

BACKGROUND

Immune and cognitive dysfunction persists even in virally suppressed women with HIV (VS-WWH). Since inflammation and HIV proteins induce the enzyme indoleamine 2,3-dioxygenase (IDO), converting tryptophan (T) to kynurenine (K) while producing downstream neurotoxic metabolites, we investigated IDO activation (KT ratio) in relation to cognition in VS-WWH and demographically similar women without HIV (WWoH).

METHODS

Ninety-nine VS-WWH on stable antiretroviral therapy and 102 WWoH (median age 52 vs 54 years; 73% vs 74% Black, respectively) from the New York and Chicago sites of the Women's Interagency HIV Study (WIHS) completed a neuropsychological test battery assessing motor function, processing speed, attention/working memory, verbal fluency, verbal learning and memory, and executive function and had plasma measured for tryptophan-kynurenine metabolites through liquid chromatography-tandem mass spectrometry and monocyte-derived [soluble cluster of differentiation-14 (sCD14), soluble cluster of differentiation-163 (sCD163), monocyte chemoattractant protein-1 (MCP-1)] plus general inflammatory markers [tumor necrosis factor alpha-2 receptor (TNF-R2), high-sensitivity C-reactive protein, high-sensitivity interleukin-6] through enzyme-linked immunosorbent assays between 2017 and 2020.

RESULTS

VS-WWH had a higher KT ratio (P < 0.01) and higher sCD14 levels (P < 0.05) compared with WWoH. Higher sCD163 was associated with higher KT ratio (R = 0.29, P < 0.01) and worse fine motor function in VS-WWH; after adjusting for sCD163 and sCD14 in multivariable regressions, higher KT ratio remained significantly associated with impaired fine motor function in VS-WWH only (standardized β = -0.29, P < 0.05). IDO activation was not associated with cognition in WWoH.

CONCLUSIONS

IDO activation (K:T) was associated with worse fine motor control in VS-WWH independent of measured systemic inflammation. Further studies investigating biological mechanisms linking IDO activation to fine motor function among VS-WWH are warranted.

Effectiveness of a home training program on improving pinch force perception in older adults

BACKGROUND

Hand function is reduced with aging which can lead to impairments in the performance of daily activities and eventually loss of independence. The ability to perceive the forces being applied to an object is an important component of hand control that also declines with age. However, the extent to which force perception can be improved through training remains largely unknown.

PURPOSE

This study evaluated the effectiveness of a home-training program focused on improving force perception in older adults.

STUDY DESIGN

Quasi-experimental - Uncontrolled trial.

METHODS

Eleven independent, healthy adults (mean age: 77.2 ± 6.8 years) participated in a home-based sensorimotor hand training program 6 days/week for 6 weeks. Force perception, the primary outcome variable, was measured as the ability to reproduce a pinch force equal to 25% maximum voluntary contraction in the absence of visual feedback using either the ipsilateral remembered or contralateral concurrent (CC) hand. We also measured hand strength, dexterity, tactile acuity, and cognition before and after training.

RESULTS

After the program was completed, participants showed a 35% reduction in absolute (p < 0.01, confidence interval (CI): [7.3, 33.2], effect sizes (ES): 0.87) and constant (p = 0.05, CI: [0.0, 34.9], ES: 0.79) force matching errors in the CC condition. Improvements in dominant hand dexterity (Purdue pegboard test) (p < 0.05, CI: [0.2, 2.4], ES: 0.60) and tactile sensitivity (JVP thresholds) (p < 0.05, CI: [-1.7, -0.1], ES: 0.94), as well as cognition (Trail Making Test B) (p < 0.05, CI: [-24,1. -1.6], ES: 0.30) were also observed post-training.

CONCLUSIONS

The results suggest that home-hand training can be an effective way to improve force perception among older adults.

Older adults are impaired in the release of grip force during a force tracking task

Age-related changes in force generation have been implicated in declines in older adult manual dexterity. While force generation is a critical aspect of the successful manipulation of objects, the controlled release of force represents the final component of dexterous activities. The impact of advancing age on the release of grip force has received relatively little investigation despite its importance in dexterity. The primary aim of this project was to determine the effects of age on the control of force release during a precision grip tracking task. Young adults (N = 10, 18-28 years) and older adults (N = 10, 57-77 years) completed a ramp-hold-release (0-35% of maximum grip force) force tracking task with their dominant hand. Compared to young adults, older adults were disproportionately less accurate (i.e., less time within target range) and had more error (i.e., greater relative root mean squared error) in the release of force, compared to generation of grip force. There was a significant difference between groups in two-point discrimination of the thumb, which was moderately correlated to force control across all phases of the task. The decline in force release performance associated with advanced age may be a result of sensory deficits and changes in central nervous system circuitry.

The BE-UJI hand function activity set: a reduced set of activities for the evaluation of the healthy and pathological hand

BACKGROUND

Hand kinematics during hand function tests based on the performance of activities of daily living (ADLs) can provide objective data to determine patients' functional loss. However, they are rarely used during clinical assessments because of their long duration. Starting with the 20 Sollerman Hand Function Test (SHFT) tasks, we propose identifying a reduced set of ADLs that provides similar kinematic information to the original full set in terms of synergies, ranges of motion and velocities.

METHODS

We followed an iterative method with the kinematics of 16 hand joints while performing the 20 ADLs of the SHFT. For each subject, ADLs were ordered according to their influence on the synergies obtained by means of a principal component analysis, the minimum number of ADLs that represented the original kinematic synergies (maximum angle of 30° between synergies), and the maintained ranges of joint movements (85% of the original ones) were selected for each subject. The set of the most frequently selected ADLs was verified to be representative of the SHFT ADLs in terms of motion strategies, ranges of motion and joint velocities when considering healthy subjects and Hand Osteoarthritis patients.

RESULTS

A set of 10 tasks, the BE-UJI activity set, was identified by ensuring a certain (minimum) similarity in synergy (maximum mean angle between synergies of 25.5°), functional joint ranges (maximum differences of 10°) and joint velocities (maximum differences of 15°/s). The obtained tasks were: pick up coins from purses, lift wooden cubes, pick up nuts and turn them, write with a pen, cut with a knife, lift a telephone, unscrew jar lids and pour water from a cup, a jar and a Pure-Pak. These activities guarantee using the seven commonest handgrips in ADLs.

CONCLUSION

The BE-UJI activity set for the hand function assessment can be used to obtain quantitative data in clinics as an alternative to the SHFT. It reduces the test time and allows clinicians to obtain objective kinematic data of the motor strategies, ranges of motion and joint velocities used by patients.