Reaction and movement times in men of different ages: a population study

The effects of age and physical exercise on multimodal signal responses: Implications for semi-autonomous vehicle takeover requests

The present study examined whether the non-chronological age factor, engagement in physical exercise, affected responses to multimodal (combinations of visual, auditory, and/or tactile) signals differently between younger and older adults in complex environments. Forty-eight younger and older adults were divided into exercise and non-exercise groups, and rode in a simulated Level 3 autonomous vehicle under four different task conditions (baseline, video watching, headway estimation, and video-headway combination), while being asked to respond to various multimodal warning signals. Overall, bi- and trimodal warnings had faster response times for both age groups across driving conditions, but was more pronounced for older adults. Engagement in physical exercise was associated with smaller maximum braking force for younger participants only, and also corresponded to longer average fixation durations, compared to the non-exercise group. Findings from this research can help to guide decisions about the design of warning and information systems for semi-autonomous vehicles.

Birth cohort differences in cognitive performance in 75- and 80-year-olds: a comparison of two cohorts over 28 years

Objective

To evaluate cohort differences in cognitive performance in older men and women born and assessed 28 years apart.

Methods

Data in this study were drawn from two age-homogeneous cohorts measured in the same laboratory using the same standardized cognitive performance tests. Participants in the first cohort were born in 1910 and 1914 and assessed in 1989–1990 (Evergreen project, n = 500). Participants in the second cohort were born in 1938 or 1939 and 1942 or 1943 and assessed in 2017–2018 (Evergreen II, n = 726). Participants in both cohorts were assessed at age 75 and 80 years and were recruited from the population register. Cognitive performance was measured using the Digit Span test from the Wechsler Memory Scale (WMS), Digit Symbol test from the Wechsler Adult Intelligence Scale (WAIS) and phonemic Verbal Fluency test from the Schaie-Thurstone Adult Mental Abilities Test. Reaction time assessing motor and mental responses was measured with a simple finger movement task, followed by a complex finger movement task. T-tests were used to study cohort differences and linear regression models to study possible factors underlying differences.

Results

We found statistically significant cohort differences in all the cognitive performance tests, except for the digit span test and simple movement task in men, the later-born cohort performing better in all the measured outcomes.

Conclusions

The results of this study provide strong evidence that cognitive performance is better in more recent cohorts of older people compared to their counterparts measured 28 years earlier.

The lack of association between herpes simplex virus 1 or Toxoplasma gondii infection and cognitive decline in the general population: An 11-year follow-up study

BACKGROUND

Inflammation has been suggested to be one, possibly treatable, cause of cognitive decline and dementia. The purpose of the present article was to investigate whether the herpes simplex virus 1 (HSV-1) or Toxoplasma gondii (T. gondii) infections are related to cognitive decline or dementia.

METHOD

The Health 2000 survey, conducted 2000-2001, is a population-representative sample of people over 30 years old that involved 7112 participants. The sample was followed up in the year 2011, in the Health 2011 study. At both time points, cognitive performance was assessed with two tests from the Consortium to Establish a Registry for Alzheimer's Disease (CERAD) assessing verbal fluency and verbal learning. In addition, the abbreviated Mini-Mental State Examination was administered to people aged over 55. In addition, tests assessing reaction and movement time were performed at baseline. Dementia diagnoses from nationwide health care registers were followed up until the end of year 2013. The presence of HSV-1 and T. gondii immunoglobulin G (IgG) was determined by solid-phase immunoassay at baseline.

RESULTS

HSV-1 or T. gondii seropositivity, or IgG antibody levels, were not associated with cognitive decline when investigated as infection × time interactions. In addition, the infections were not associated with the risk of dementia.

CONCLUSIONS

In a large sample of participants that is representative of the whole country and with a long follow-up, the results suggest that latent HSV-1 or T. gondii infections are not related to either decline in cognitive performance or dementia risk.

Active aging - resilience and external support as modifiers of the disablement outcome: AGNES cohort study protocol

Background

Population aging increases the need for knowledge on positive aspects of aging, and contributions of older people to their own wellbeing and that of others. We defined active aging as an individual’s striving for elements of wellbeing with activities as per their goals, abilities and opportunities. This study examines associations of health, health behaviors, health literacy and functional abilities, environmental and social support with active aging and wellbeing. We will develop and validate assessment methods for physical activity and physical resilience suitable for research on older people, and examine their associations with active aging and wellbeing. We will examine cohort effects on functional phenotypes underlying active aging and disability.

Methods

For this population-based study, we plan to recruit 1000 participants aged 75, 80 or 85 years living in central Finland, by drawing personal details from the population register. Participants are interviewed on active aging, wellbeing, disability, environmental and social support, mobility, health behavior and health literacy. Physical activity and heart rate are monitored for 7 days with wearable sensors. Functional tests include hearing, vision, muscle strength, reaction time, exercise tolerance, mobility, and cognitive performance. Clinical examination by a nurse and physician includes an electrocardiogram, tests of blood pressure, orthostatic regulation, arterial stiffness, and lung function, as well as a review of chronic and acute conditions and prescribed medications. C-reactive protein, small blood count, cholesterol and vitamin D are analyzed from blood samples. Associations of factors potentially underlying active aging and wellbeing will be studied using multivariate methods. Cohort effects will be studied by comparing test results of physical and cognitive functioning with results of a cohort examined in 1989–90.

Conclusions

The current study will renew research on positive gerontology through the novel approach to active aging and by suggesting new biomarkers of resilience and active aging. Therefore, high interdisciplinary impact is expected. This cross-sectional study will not provide knowledge on temporal order of events or causality, but an innovative cross-sectional dataset provides opportunities for emergence of novel creative hypotheses and theories.

Association of cytomegalovirus and Epstein-Barr virus with cognitive functioning and risk of dementia in the general population: 11-year follow-up study

BACKGROUND

Earlier studies have documented an association between cytomegalovirus and cognitive impairment, but results have been inconsistent. Few studies have investigated the association of cytomegalovirus and Epstein-Barr virus with cognitive decline longitudinally. Our aim was to examine whether cytomegalovirus and Epstein-Barr virus are associated with cognitive decline in adults.

METHOD

The study sample is from the Finnish Health 2000 Survey (BRIF8901, n = 7112), which is representative of the Finnish adult population. The sample was followed up after 11 years in the Health 2011 Survey. In addition, persons with dementia were identified from healthcare registers.

RESULTS

In the Finnish population aged 30 and over, the seroprevalence of cytomegalovirus was estimated to be 84% and the seroprevalence of Epstein-Barr virus 98%. Seropositivity of the viruses and antibody levels were mostly not associated with cognitive performance. In the middle-aged adult group, cytomegalovirus serointensity was associated with impaired performance in verbal learning. However, the association disappeared when corrected for multiple testing. No interactions between infection and time or between the two infections were significant when corrected for multiple testing. Seropositivity did not predict dementia diagnosis.

CONCLUSIONS

The results suggest that adult levels of antibodies to cytomegalovirus and Epstein-Barr virus may not be associated with a significant decline in cognitive function or with dementia at population level.

Factors Affecting Reaction-Time Testing and the Interpretation of Results

The aim of this study was to identify factors that might affect reaction-time (RT) testing and interpretation. Simple reaction time and choice reaction time were measured in a cohort of 893 white young men. Age, body size, color vision, and intelligence (IQ) were analyzed as subject-related factors. Effects of time of day of test and different examiners were analyzed in relation to testing facilities. All factors were statistically correlated to RTs; however, the relationships between age and RTs and between height and RTs were noticeably weak and apparently insignificant in practice. A defect in color vision was notably associated with slow choice RT and with mistakes on the test. As the choice was coded by color in the choice RT test, the result was expected. Low IQs were significantly related with slow RTs. Slow RTs have been correlated with low-grade IQs in previous studies also. Lower grades and greater variation in RTs were recorded just before meals or if testing was done outside the daily testing schedule. The examiner supervising the RT testing significantly affected the results. It was concluded that the introduction for tests should be given impersonally using a tape recorder or comparable equipment.

Longitudinal Analysis of Age-Related Slowing: BLSA Reaction Time Data

Reported are preliminary findings from analyses of cross-sectional and longitudinal reaction time data collected on 865 male and 453 female volunteers who ranged in age from 20 to 96 years. Evident in both simple and disjunctive reaction time measures was a consistent slowing with age. In nearly all cases, males were faster than females but gender differences were negligible for the simple reaction time (SRT) compared to disjunctive reaction time (DRT). Repeated testing within subjects over 2–8 years also showed age-related slowing across decades. Cross-sectional studies have been criticized for overestimating the actual age-related slowing found in longitudinal analysis. However, this was not the case in the present research. Similar effects were observed in analyses of data from all subjects on their first visit (n = 1318 subjects) compared to data from all subjects over all of their visits (n = 3855 subject visits) compared to data from only those subjects across decades who were tested repeatedly over at least 8 years (n = 314 subjects X 5 visits = 1570 subject visits). Findings from this research have human factors implications for task design, personnel selection, performance prediction, accident analysis, human tests and measurements, and demographic norms, to mention a few.

Correlations between sensory-motor functions and motor performance measured by optoelectronic kinesiology in 75-year-olds

The motor performance in an everyday motor task, lifting an object from the floor and placing it on a shelf - the Posturo-Locomotor-Manual test (PLM test) - was recorded using optoelectronic kinesiology in 150 subjects within a broader study measuring functional capacity in 75-year-olds (the NORA 75 study). The results were correlated in all persons to tests for isometric muscle strength, visual acuity, postural balance, vibrotactile threshold, reaction time, pulmonary function and maximal walking speed. The PLM test performance correlated well with the isometric muscle strength measurements in men and strong individuals were consequently faster than weaker persons. A moderate correlation was found with pulmonary function in men. The association between the PLM test parameters and muscle strength was poor in women. Subjects with slower psychomotor and walking speed moved significantly slower in the PLM test in both sexes. No association was found with visual acuity, postural balance or vibrotactile threshold. The PLM test might be used to identify individuals at risk of disability caused by decline in muscle strength.

Insulin resistance is associated with poorer verbal fluency performance in women

AIMS/HYPOTHESIS

Type 2 diabetes is an independent risk factor for cognitive decline. Insulin resistance occurring during midlife may increase the risk of cognitive decline later in life. We hypothesised that insulin resistance is associated with poorer cognitive performance and that sex and APOE*E4 might modulate this association.

METHODS

The association of insulin resistance and APOE*E4 genotype on cognitive function was evaluated in a nationwide Finnish population-based study (n = 5,935, mean age 52.5 years, range 30-97 years). HOMA-IR was used to measure insulin resistance. Cognitive function was tested by word-list learning, word-list delayed-recall, categorical verbal fluency and simple and visual-choice reaction-time tests. Linear regression analysis was used to determine the association between HOMA-IR and the results of the cognitive tests.

RESULTS

Higher HOMA-IR was associated with poorer verbal fluency in women (p < 0.0001) but not in men (p = 0.56). Higher HOMA-IR was also associated with poorer verbal fluency in APOE*E4 -negative individuals (p = 0.0003), but not in APOE*E4 carriers (p = 0.28). Furthermore, higher HOMA-IR was associated with a slower simple reaction time in the whole study group (p = 0.02).

CONCLUSIONS/INTERPRETATION

To our knowledge, this is the first comprehensive, population-based study, including both young and middle-aged adults, to report that female sex impacts the association of HOMA-IR with verbal fluency. Our study was cross-sectional, so causal effects of HOMA-IR on cognition could not be evaluated. However, our results suggest that HOMA-IR could be an early marker for an increased risk of cognitive decline in women.

An examination of the mechanisms underlying the effects of physical activity on brain and cognition

Physical activity positively influences brain health and cognitive functioning in older adults. Several physiological and psychological mechanisms have been identified to underlie such a relationship. Cardiovascular fitness is accompanied with changes in mechanisms such as cerebral blood flow, neurotrophic factors, neurotransmitter systems and neural architecture that have themselves been associated with cognitive performance. Factors associated with exercise such as arousal, mood and self-perception of competence seem also to influence cognitive performance. Other explanation for the benefits of exercise in cognition, results from the fact that the performance of motor skills involve an important cognitive component (e.g., executive functions and information processing speed). Evidence of brain plasticity and behavior has been provided from studies where animals are exposed to enriched or complex environments. Exposure to such paradigms in which physical activity plays an important role has been found to influence various aspects of brain function and structure. Studies using neuroimaging techniques have established a link between the acquisition of different motor skills and the occurrence of neuroplasticity in human adults. This literature review indicates that the type of exercise and its specific perceptual and cognitive characteristics may influence cognitive performance. However, most of the research has been focused on self-paced movements or automatized skills and few intervention studies have examined the results of merging exercise and cognitive training in a single program. An important scientific challenge for the coming years is to design exercise programs capable of mobilizing several type of mechanisms underlying the effects of physical activity on brain and cognition.

Psychomotor speed in a random sample of 7,979 subjects aged 30 years and over

BACKGROUND AND AIMS

Slowing of psychomotor speed among older individuals has been shown in numerous studies. However, in most cases these studies were based on small and selected groups of people and, in some cases, the test procedures did not allow separation of decision time and motor components of the overall performance. The purpose of the present study was to analyse in a large, randomly selected population sample the differences in decision and movement times in simple and multiple-choice test conditions. The association of educational background with psychomotor speed was also examined.

METHODS

Data on psychomotor speed were collected from a representative nation- wide sample of the Finnish population aged 30 years and over (n=7979) with the help of a computerized device in simple and multiple-choice test conditions, with visual stimuli. Background information (education) was collected by a structured interview.

RESULTS

Results showed a systematic and significant decline in both decision time and movement time when proceeding from the youngest (30-39-year-olds) to the oldest (80+ yrs) age groups. This decline was more pronounced in the multiple-choice test than in the simple test. In both test conditions, movement times were shorter in men than in women. In the young and middle-aged groups, participants with longer formal education were faster than the less educated subjects.

CONCLUSIONS

On the basis of the large representative random sample of this study, it may be concluded that decline in psychomotor speed during aging can already be seen at a quite young age. Decline accelerates after the age of about 70. Differences in socio-economic background factors, such as education, may modify the differences observed between younger and older individuals. These results emphasize the need for the separation of decision time and movement time in psychomotor speed tests, when differences between age groups as well as between men and women are analysed.

Psychomotor slowness is associated with self-reported sleep duration among the general population

Short and long self-reported sleep durations have been found to be associated with several seemingly disparate health risks and impaired functional abilities, including cognitive functioning. The role of long sleep is especially poorly understood in this context. Psychomotor slowness, shown to have analogous associations with cognitive performance and health risks as self-reported long sleep duration, has not been studied together with sleep duration in epidemiological settings. We hypothesized that self-reported habitual sleep duration, especially long sleep, is associated with slow psychomotor reaction time, and that this association is independent of vigilance-related factors. The hypothesis was tested in a sample of 5352 individuals, representing the general adult population. We found a U-shaped association between self-reported sleep duration and psychomotor speed, which prevailed even after controlling for several pertinent confounders. This novel finding can be interpreted to mean that self-reported sleep duration, at least in the case of long sleep, is an indicator of bodily/brain integrity and, taken together with the results of cognitive epidemiology, may provide some new insights into the mechanisms underlying the associations between habitual self-reported sleep duration, health risks and impaired functional abilities.

Between destiny and disease: genetics and molecular pathways of human central nervous system aging

Aging of the human brain is associated with "normal" functional, structural, and molecular changes that underlie alterations in cognition, memory, mood and motor function, amongst other processes. Normal aging also imposes a robust constraint on the onset of many neurological diseases, ranging from late onset neurodegenerative diseases, such as Alzheimer's (AD) and Parkinson's diseases (PD), to early onset psychiatric disorders, such as bipolar disorder (BPD) and schizophrenia (SCZ). The molecular mechanisms and genetic underpinnings of age-related changes in the brain are understudied, and, while they share some overlap with peripheral mechanisms of aging, many are unique to the largely non-mitotic brain. Hence, understanding mechanisms of brain aging and identifying associated modulators may have profound consequences for the prevention and treatment of age-related impairments and diseases. Here we review current knowledge on age-related functional and structural changes, their molecular and genetic underpinnings, and discuss how these pathways may contribute to the vulnerability to develop age-related neurological diseases. We highlight recent findings from human post-mortem brain microarray studies, which we hypothesize, point to a potential genetically controlled transcriptional program underlying molecular changes and age-gating of neurological diseases. Finally, we discuss the implications of this model for understanding basic mechanisms of brain aging and for the future investigation of therapeutic approaches.

Age-related differences in postural reaction time and coordination during voluntary sway movements

The elderly are known to exhibit declines in postural control during standing and walking, however little is known about how the elderly react under time-critical and challenging postural situations. The purpose of this study was to examine age-related differences in reaction time (RT) and the pattern of temporal coordination between center of pressure (COP), trunk and head motion during voluntary postural sway movements. Healthy young (n=10; mean=24 years; SD=5 years) and elderly men (n=8; mean=75 years; SD=2 years) stood on a force plate with tri-axial accelerometers attached to the head and lower trunk. Participants were required to generate sway in the anterior-posterior (AP) or medial-lateral (ML) direction in response to an auditory cue during two different testing conditions called Static reaction and Dynamic reaction. Static reactions involved the initiation of voluntary sway in either the AP or ML direction from quiet stance. Dynamic reactions involved an orthogonal switch of voluntary sway between the AP and ML directions. Compared to the young, elderly individuals exhibited slower RT during both Static and Dynamic reaction, and smaller differences in RT and phasing between COP, trunk, and head motion. The results of this study suggest that the elderly adopted more rigid coordination strategies compared to the young when executing a rapid change in direction of whole body motion. The rigid movement strategy of the elderly was presumably generated in an effort to compensate for increased challenge to the maintenance of stability.

A meta-regression to examine the relationship between aerobic fitness and cognitive performance

Many studies have been conducted to test the potentially beneficial effects of physical activity on cognition. The results of meta-analytic reviews of this literature suggest that there is a positive association between participation in physical activity and cognitive performance. The design of past research demonstrates the tacit assumption that changes in aerobic fitness contribute to the changes in cognitive performance. Therefore, the purpose of this meta-analysis was to use meta-regression techniques to statistically test the relationship between aerobic fitness and cognitive performance. Results indicated that there was not a significant linear or curvilinear relationship between fitness effect sizes (ESs) and cognitive ESs for studies using cross-sectional designs or posttest comparisons. However, there was a significant negative relationship between aerobic fitness and cognitive performance for pre-post comparisons. The effects for the cross-sectional and pre-post comparisons were moderated by the age group of the participants; however, the nature of this effect was not consistent for the two databases. Based on the findings of this meta-analytic review, it is concluded that the empirical literature does not support the cardiovascular fitness hypothesis. To confirm the findings of this review, future research should specifically test the dose-response relationship between aerobic fitness and cognitive performance. However, based upon the findings of this review, we also encourage future research to focus on other physiological and psychological variables that may serve to mediate the relationship between physical activity and cognitive performance.

Motor speed and lower extremity strength as predictors of fall-related bone fractures in elderly individuals

BACKGROUND AND AIMS

The purpose of this prospective population-based study was to examine the combined effects of motor speed and knee extension strength on risk of fall-related bone fractures in elderly individuals over a 10-year period.

METHODS

Participants were 307 men and women aged 75 or 80 years at baseline, who visited the research laboratory at the University of Jyväskylä, Finland. Multi-choice motor speed tests and maximal isometric knee extension strength tests were carried out at baseline. Information on fractures was collected from hospital and health center records. The presence of impairment was defined as a score in the lowest tertile of sex- and age-stratified distribution of results in each test.

RESULTS

During the 10-year period, 93 participants had at least one fracture. In Cox proportional hazards models for motor speed and knee extension strength, the risk of fracture was almost double in the lowest vs the highest tertile of each test score. For those in the poorest speed and strength tertiles compared with the best speed and strength tertiles, the relative risk of fracture adjusted for age, sex and bone mineral density was 4.69 (95% confidence interval 1.72-12.81).

CONCLUSIONS

Increased risk of fracture was observed for those with either slow motor speed or poor lower extremity strength; however, a combination of these impairments increased the fracture risk significantly when compared with those with no impairments. A co-impairment approach may prove useful in gaining better understanding of the risk of fall-related bone fractures and the development of effective interventions.

Animal models of behavioral dysfunctions: Basic concepts and classifications, and an evaluation strategy

In behavioral neurosciences, such as neurobiology and biopsychology, animal models make it possible to investigate brain-behavior relations, with the aim of gaining insight into normal and abnormal human behavior and its underlying neuronal and neuroendocrinological processes. Different types of animal models of behavioral dysfunctions are reviewed in this article. In order to determine the precise criteria that an animal model should fulfill, experts from different fields must define the desired characteristics of that model at the neuropathologic and behavioral level. The list of characteristics depends on the purpose of the model. The phenotype-abnormal behavior or behavioral dysfunctions-has to be translated into testable measures in animal experiments. It is essential to standardize rearing, housing, and testing conditions, and to evaluate the reliability, validity (primarily predictive and construct validity), and biological or clinical relevance of putative animal models of human behavioral dysfunctions. This evaluation, guided by a systematic strategy, is central to the development of a model. The necessity of animal models and the responsible use of animals in research are discussed briefly.

Postural Balance in a Random Sample of 7,979 Subjects Aged 30 Years and Over

BACKGROUND

Reliable normative data for force platform measurements of postural balance have not been available.

METHODS

Data on postural balance were collected from a representative nationwide sample of a Finnish population aged >or=30 years (n = 7,979). As part of a comprehensive health survey (Health 2000), postural balance was measured with the help of a force platform system in four test conditions: normal standing with eyes open and closed (both for 30 s), semi-tandem (20 s) and tandem stand with eyes open (20 s). In addition, balance abilities were also evaluated by a non-instrumented field test.

RESULTS

The main findings of this study indicated that the differences in balance between subjects belonging to different age categories were apparent already among young and middle-aged subjects. This is true, however, only for the more accurate force platform measurements, as the field test showed a clear ceiling effect up to 60 years of age. At higher ages both methods indicated a further, accelerating decline in balance function. In most cases, males tended to have more pronounced sway, as indicated by the speed and amplitude aspects of the movement of the center of pressure during the force platform registrations and these differences were larger in the older age groups. In contrast, in the field test a larger proportion of males were able to achieve the highest category (10 s in tandem stand) and the proportion of subjects unable to stand for a minimum of 10 s feet side by side was larger among females than males. These observations may partly be due to differences in the participation/acceptable performance in the different tests. In addition, the field test and force platform measurements may partially reflect different aspects of balance abilities.

CONCLUSION

The results of the present study provide normative values for force platform balance tests at an age of 30 years and above. Deterioration in balance function clearly starts at relatively young ages and further accelerates from at about 60 years upwards. Due to systematic differences between males and females, separate normative values for both sexes are needed. Due to marked ceiling effects the field test can only be recommended for older individuals, aged >/=60. On the other hand, force platform registrations in the more demanding tests (semi-tandem and tandem stands) suffer from floor effects in the oldest age groups.

A cohort study found good respiratory, sensory and motor functions decreased mortality risk in older people

BACKGROUND AND OBJECTIVE

The main aims of this study were to evaluate the separate and joint effects of respiratory, sensory, and psychomotor function, muscle strength, and mobility in predicting mortality in older men and women, and to find a way to control multicollinearity in a multivariate Cox regression model.

METHODS

Mortality was followed for 10 years (1990-2000) in an entire cohort of 75-year-old residents of the city of Jyvaskyla, Finland (born in 1914; N=388). Cox regression models and principal component estimation were employed to study the association between the covariates and mortality.

RESULTS

The study indicated that, after adjustment for fatal diseases and cognitive capacity, vital capacity, tapping rate, muscle strength, and walking speed predict mortality in elderly men and women to a similar extent. The hazard ratio for mortality for those in the lowest tertile of the principal component representing all the significant physiological functions was from three to four times higher than for those in the highest tertile.

CONCLUSION

Our results suggest that a poor level in any of the measured functions has a similar impact on the risk for mortality, which is further increased by combining the different results. No single, dominant predictor of mortality emerged.

Components of Response Time as a Function of Age, Physical Activity, and Aerobic Fitness

Research suggests that there are differences in response time (RespT) as a function of age but that aerobic fitness might have a facilitatory effect on RespT. This study was designed to examine this relationship while addressing methodological issues from past research. Men from 3 age groups completed speeded tasks, a physical activity questionnaire, and an aerobic-fitness test. Results indicated that age has a negative impact on RespT (specifically premotor time and movement time). The interaction of aerobic fitness by age was also a significant predictor of RespT (specifically movement time) such that aerobic fitness was positively related to speed of performance for older participants. It is concluded that aerobic fitness might serve a preservative function for speeded tasks in older adults.

Evaluating the interdependence of aging-related changes in visual and auditory acuity, balance, and cognitive functioning

High proportions of shared age-related variance are found among measures of perceptual acuity, balance, muscle strength, and cognitive capabilities in age-heterogeneous, cross-sectional studies. Reliance on cross-sectional studies is problematic, however, because associations may arise from age-related mean trends. Narrow age-cohort samples provide an alternative basis for testing hypotheses regarding associations among rates of change. Cross-domain associations were evaluated in combined 75-year-old cohort samples from Denmark, Finland, and Sweden. In general, no consistent associations were found across sensory, balance, strength, and cognitive domains. These findings indicate that the effects of aging on sensory acuity, balance, and cognitive functioning are likely to be largely independent, multidimensional, and complex at the level of the individual.

Age-dependent variations in the directional sensitivity of balance corrections and compensatory arm movements in man

We investigated the effects of ageing on balance corrections induced by sudden stance perturbations in different directions. Effects were examined in biomechanical and electromyographic (EMG) recordings from a total of 36 healthy subjects divided equally into three age groups (20-34, 35-55 and 60-75 years old). Perturbations consisted of six combinations of support-surface roll (laterally) and pitch (forward-backward) each with 7.5 deg amplitude (2 pure pitch, and 4 roll and pitch) delivered randomly. To reduce stimulus predictability further and to investigate scaling effects, perturbations were at either 30 or 60 deg s(-1). In the legs, trunk and arms we observed age-related changes in balance corrections. The changes that appeared in the lower leg responses included smaller stretch reflexes in soleus and larger reflexes in tibialis anterior of the elderly compared with the young. For all perturbation directions, onsets of balance correcting responses in these ankle muscles were delayed by 20-30 ms and initially had smaller amplitudes (between 120-220 ms) in the elderly. This reduced early activity was compensated by increased lower leg activity after 240 ms. These EMG changes were paralleled by comparable differences in ankle torque responses, which were initially (after 160 ms) smaller in the elderly, but subsequently greater (after 280 ms). Findings in the middle-aged group were generally intermediate between the young and the elderly groups. Comparable results were obtained for the two different stimulus velocities. Stimulus-induced trunk roll, but not trunk pitch, changed dramatically with increasing age. Young subjects responded with early large roll movements of the trunk in the opposite direction to platform roll. A similarly directed but reduced amplitude of trunk roll was observed in the middle-aged. The elderly had very little initial roll modulation and also had smaller stretch reflexes in paraspinals. Balance-correcting responses (over 120-220 ms) in gluteus medius and paraspinals were equally well tuned to roll in the elderly, as in the young, but were reduced in amplitude. Onset latencies were delayed with age in gluteus medius muscles. Following the onset of trunk and hip balance corrections, trunk roll was in the same direction as support-surface motion for all age groups and resulted in overall trunk roll towards the fall side in the elderly, but not in the young. Protective arm movements also changed with age. Initial arm roll movements were largest in the young, smaller in the middle aged, and smallest in the elderly. Initial arm roll movements were in the same direction as initial trunk motion in the young and middle aged. Thus initial roll arm movements in the elderly were directed oppositely to those in the young. Initial pitch motion of the arms was similar across age groups. Subsequent arm movements were related to the amplitude of deltoid muscle responses which commenced at 100 ms in the young and 20-30 ms later in the elderly. These deltoid muscle responses preceded additional arm roll motion which left the arms directed 'downhill' (in the direction of the fall) in the elderly, but 'uphill' (to counterbalance motion of the pelvis) in the young. We conclude that increased trunk roll stiffness is a key biomechanical change with age. This interferes with early compensatory trunk movements and leads to trunk displacements in the direction of the impending fall. The reversal of protective arm movements in the elderly may reflect an adaptive strategy to cushion the fall. The uniform delay and amplitude reduction of balance-correcting responses across many segments (legs, hips and arms) suggests a neurally based alteration in processing times and response modulation with age. Interestingly, the elderly compensated for these 'early abnormalities' with enlarged later responses in the legs, but no similar adaptation was noted in the arms and trunk. These changes with age provide an insight into possible mechanisms underlying falls in the elderly.

Motor slowing and parkinsonian signs in aging rhesus monkeys mirror human aging

Motor slowing is a universal feature of human aging, and parkinsonian signs are commonly expressed in human senescence. In the present study, age-associated declines in motor functions in 31 female rhesus monkeys were quantified by activity monitors and an automated test panel, and the incidence of parkinsonian signs was scored using a movement dysfunction assessment scale. Activity levels in middle-aged monkeys (12-17 years old) were less than half that of young animals (5-8 years old) and were further depressed in aged monkeys (21-27 years old). Movement dysfunction scores increased significantly with increasing age. Two or more parkinsonian signs were exhibited by 20% of the middle-aged monkeys and 36% of the aged monkeys. Slowing performance times on fine-motor hand tasks correlated significantly with increasing age. Motor learning was seen in all age groups, but improved faster in the young monkeys. The data suggest that aging rhesus monkeys provide an appropriate model to analyze the biological processes leading to motor slowing and the expression of parkinsonian signs in human senescence.

An automated movement assessment panel for upper limb motor functions in rhesus monkeys and humans

As part of our studies of age-associated changes in motor functions, we have designed an automated movement assessment panel (MAP) to evaluate upper limb and hand movements. Here we describe two versions of the MAP, one for human testing and one for nonhuman primates, and methods for conducting parallel tests in rhesus monkeys and human volunteers. The results are reported from a battery of tests on young adult rhesus monkeys (n = 10, 5-8 years old), young adult human subjects (n = 10, 18-22 years old) and ten aged human subjects (n = 10, 66-68 years old) to demonstrate the capability of the MAP in quantifying arm and hand movement times. The performance times on the two simplest tasks tested were consistent from trial to trial, demonstrating that a stable behavioral baseline could be established for evaluating changes in motor functions over time and assessing treatments for improving motor functions. Motor learning was seen in the more complex movement tasks tested, indicating their usefulness in analyzing this behavior. Finally, age-associated changes in performance times were robustly delineated by the four tasks evaluated in the human subjects.

Effects of a three-month active rehabilitation program on psychomotor performance of lower limbs in subjects with low back pain: a controlled study with a nine-month follow-up

Proper psychomotor performance is needed in work and in activities of daily living, but among subjects with low back pain this area has been studied little. The present purpose was to evaluate the effect and permanence of a 3-mo. physical exercise program on the psychomotor performance of lower limbs in subjects with low back pain. The associations between psychomotor performance and intensity of low back pain and subjective disability were also evaluated. 90 subjects with nonspecific, subacute low back pain were assigned to one of the three groups: one given three months intensive training, one home exercise, or the control group. Four measurement sessions were made during the 1-yr. study. Psychomotor speed of lower limbs was analyzed with Choice Reaction Time, Movement Time, and Total Response Time. Flight Time of a vertical static jump was also measured. Muscle strength was assessed with conventional methods from trunk, lower limbs, and hand. Intensity of Current Back Pain was analyzed with the Borg scale. Subjective disability was evaluated with the Oswestry Index. Analysis showed that muscle strength and back pain intensity had associations with psychomotor performance but subjective disability or physical activity did not affect it noticeably. There were no changes in Choice Reaction Time, but Total Response Time and Movement Time decreased and Flight Time increased for all subjects. In the first postintervention measurement the home exercise group had significantly lower Movement Time than the intensively trained group. Back Pain Intensity decreased in both exercise groups for those subjects whose psychomotor performance values were below the mean value for the sample.

Psychomotor speed in chronic low-back pain patients and healthy controls: construct validity and clinical significance of the measure

The effect of ethanol on reaction times was studied in 5 healthy men to test the construct validity of the measure. Reaction times were studied among 61 healthy controls and 99 patients with chronic low-back pain (68 moderate and 31 severe) to evaluate the diagnostic value of reaction time measurements. Analysis of receiver operating characteristics was used to calculate the discriminative power of the reaction time measurements. The severity of low-back pain was associated with slow reaction times but the diagnostic value of a single reaction time measurement was low due to insufficient sensitivity. In conclusion, even though many patients with low-back pain suffer from central impairment of motor function, a single reaction time measurement is not usable in evaluation of the severity of low-back pain.

The effect of lifelong exercise on psychomotor reaction time: a study of 38 pairs of male monozygotic twins

PURPOSE

The aim was to study the effect of lifetime physical activity on psychomotor speed.

METHODS

Foot and dominant hand visual simple and choice psychomotor reaction times were studied among monozygotic twins (38 pairs) aged 35-69, discordant for lifetime exercise histories.

RESULTS

There was a trend that some components of psychomotor reaction time were faster for frequent than for occasional exercisers, but the findings were not consistent for the hand and feet. After controlling for occupational physical activity, only choice decision time for the hand (26 ms, P < 0.01) and choice reaction time for the contralateral foot (51 ms, P < 0.05) both remained 7% faster. There was no trend for systematic differences in reaction times between twins engaged in regular exercise versus their siblings exercising infrequently.

CONCLUSIONS

Results suggest a somewhat smaller effect of exercise than reported in previous studies. Reaction time may be significantly affected only by vigorous, frequent exercise. Thus, health promotion through exercise may be unlikely to have notable effects on reaction time.

The Effects of Complexity, Practice, Warm-Up, and Fatigue on Finger Tapping in Younger and Older Women

This study investigated age-related differences in tapping speed with respect to warm-up and fatigue effects and also with respect to task complexity. An additional purpose was to determine the site of age-related slowing in stationary tapping. Adult females from three different age groups were asked to tap as fast as possible for 25 s with a specified digit combination by depressing microswitches on one or two metal boxes that were mounted on a data acquisition board. All groups showed a warm-up period during the first block, reached their peak tapping speed during the second block, and then gradually fatigued, as indicated by a decreasing number of taps. These findings suggest that to assess true tapping speed, a trial should not last more than 15 s, or the results may be confounded by fatigue effects. It was found that tapping with the thumb and index finger simultaneously is more difficult than tapping with one or both index fingers, regardless of age.

Psychomotor speed and physical activity in 75-year-old residents in three Nordic localities

Psychomotor speed was studied in samples of 75-year-old men and women in three Nordic localities, namely Glostrup (Denmark), Gothenburg (Sweden), and Jyväskylä (Finland). Both simple and multi-choice reaction and movement time tests were applied using visual and auditory stimuli. The aim of the present report was to analyze the role of habitual physical activity and physical fitness as associates of psychomotor speed. The results indicated a higher psychomotor speed in the physically more active and, in most cases, fitter subjects in both the simple and more complex tasks, a higher speed of performance in men compared to women, and, to some extent, more favorable values in Gothenburg and Jyväskylä than in Glostrup. The overall findings suggest that habitual physical activity may enhance psychomotor speed in elderly subjects. Basic differences in activity did not, however, explain the differences in psychomotor speed observed between the localities or between the sexes.

Comparison of foot and hand reaction times among men: a methodologic study using simple and multiple-choice repeated measurements

The primary study goal was to compare visual simple and choice reaction times of the hand and foot to assess validity of measurements for evaluating subjects' ability to perform rapid, controlled movements. First, we examined the repeatability (N = 34) for four different data-sampling methods from a series of 12 trials within sessions and between two test sessions. Simple and choice reaction times with the preferred hand and both feet were then compared among 153 healthy male volunteers aged 35 to 67 years. Pearson correlations for hand and ipsilateral and contralateral foot reaction times on simple and choice tasks (.53 to .80, p < .001) showed that psychomotor foot reaction time is a valid method for study of neuromuscular control of lower extremities.

Performance on motor tasks as an indication of increased behavioral asymmetry with advancing age

Age-related asymmetrical functional decline was tested on a sample of 64 right-handed volunteers between 60 and 64 years of age who were free from neurological illnesses and physical handicaps. Increase in functional asymmetry was explored by examining performance indexes for each hand and superiority of the dominant hand on motor tasks of different complexities: the Finger Tapping Test, the Grooved Pegboard Test, and the Pin Test. Our study revealed an increase in superiority of the right hand with age on a highly demanding task (Pin Test). This finding is discussed in light of the hypothesis of a decline in callosal functioning with age and the alternative hypothesis of a greater vulnerability of the right hemisphere in the elderly.

Correlation between physical activity and the gait characteristics and ankle joint flexibility of the elderly

The correlation between the type, duration and intensity of physical activity on the gait characteristics and the range of active ankle joint motion of the elderly were investigated in this study. Three-dimensional (3D) kinetic and kinematic assessments were performed on the normal walking patterns of 59 healthy elderly male and female subjects (aged 60-79 years). Gait analysis was performed using a high-speed video-based (3D) motion analysis system with synchronized ground-reaction force measurements. The maximal active range of motion (RoM) of the ankle joint complex of each subject was determined using an external six-degree-of-freedom flexibility assessment device. Physical activity levels were classified based on energy expenditure requirements. In general the results suggest that habitual level of physical activity did not have a significant effect on the kinetic or kinematic variables during walking, or the maximal ankle joint range of motion. Differences in ankle joint RoM and gait variables were found based on gender. No distinct benefit with respect to ankle joint range of motion or gait characteristics was provided with participation in higher-energy intensive physical activities in comparison to physical activities requiring low to moderate energy expenditures. It is speculated that the benefits of physical activity may be more pronounced in activities which demand rapid muscular strength and control movements such as recovering from a fall or obstacle avoidance. RELEVANCE: Participation in low-energy intensity activities provides the same benefits to ankle joint flexibility and locomotion, without the added risk of injury associated with high-energy intensity sports. This finding has important implications with respect to physical activity programmes for the elderly with an objective to maintain or improve independent mobility.

Factors related to carrying out everyday activities among elderly people aged 80

The study was based on an epidemiological model in which performing activities of daily living (ADL) was the dependent variable. Variation in performing was explained by physical and mental health, and by physical performance. The population consisted of all 80-year-old residents (N = 291) of the city of Jyväskylä in central Finland; 90% of them agreed to take part in the interviews at home, while 72% took part in the laboratory examinations to determine health status and functional capacity. Difficulties in at least some PADL (Physical Activities of Daily Living) tasks were reported by 86.5% of the men, and 87.2% of the women; none said they could perform all IADL (Instrumental Activities of Daily Living) tasks without difficulty. Physical performance (grip strength and stair mounting test in men, and stair mounting test, balance, and upper extremity function test in women) and visual acuity showed a significant association with ADL performance both in men and in women. In addition, depressive symptoms in women, and cognitive capacity in men were associated with both PADL and IADL, and ADL performance, respectively. In the search for pathways to reduced ADL performance, it is important to look not only at chronic diseases but also at the aging processes as well as the disabilities caused by inactivity. Tests of cognitive capacity, psychological well-being and physical performance provide valuable information on the factors that underlie the aged individual's reduced functional capacity.

Influence of muscle activation dynamics on reaction time in the elderly

The aim of this investigation was to determine whether age-related changes in the dynamics of muscle activation were, in part, responsible for longer reaction times (RT) in the elderly. A group of 12 young (mean age, 20.6 years) and 12 elderly (mean age, 64.3 years) women performed a series of ballistic forearm supination movements in response to an auditory stimulus while using a simple reaction time test. Surface electromyographic waveforms from biceps brachii (agonist) and pronator teres (antagonist) muscles were recorded, together with the angle-time curves representing the motion of the forearm, on to an IBM compatible microcomputer. The results showed that an age-related increase (P < 0.05) in motor reaction time (MRT) contributed to longer RT in the elderly. In addition, the longer (P < 0.05) MRTs in the elderly were associated with a significantly slower rate (P < 0.05) of biceps brachii muscle activation and a significantly increased proportion (P < 0.05) of the initial biceps brachii muscle burst required to initiate the movement. This data suggested that an important part of the slowing of motor behaviour, commonly observed with increasing age, may be due to either decreases in the ability of aged skeletal muscle to rapidly generate tension or to a reduction in motor drive.

Sensitivity of the central visual field in 70- to 81-year-old male athletes and in a population sample

The sensitivity of the central visual field (0 degree-30 degrees) was studied using an automatic Octopus 500E perimeter in elderly male athletes and in a population sample of men of corresponding age. The athletes (N = 96) were endurance and power athletes, who were still active in competitive sports with training histories spanning tens of years. The athletes' results were compared with those of a sample of men of the same age (70-81 years, N = 41) randomly selected from the local population register. The sensitivity values of the athletes, and the endurance athletes in particular, were significantly better than those of the controls, with differences varying from 1 to 2.5 dB in the different areas of the central visual field. Multivariate analyses of the background factors of visual field sensitivity showed that the most important were age, amount of annual training, number of chronic diseases, HDL-cholesterol level, and vital capacity. The results suggest that a long training history, especially of the aerobic type, may be beneficial with respect to the sensitivity of the visual system.

Physical Activity, Age, and Cognitive-Neuropsychological Function

Findings from three research paradigms that employed aerobic exercise as an independent variable were used to test the hypothesis that aerobic exercise improves cognitive-neuropsychological functioning. The research paradigms were animal intervention studies, cross-sectional human studies, and human intervention studies. Results from studies of animals, usually rodents, provide consistent evidence that aerobic fitness is associated with improved neurobiological and behavioral functioning. Cross-sectional studies with humans indicate a strong positive association between physical activity level and cognitive-neuropsychological performance. However, results from these studies must be interpreted cautiously, as individuals who elect to exercise or not exercise may differ on other variables that could influence cognitive-neuropsychological performance. To date, human intervention studies have not consistently demonstrated cognitive-neuropsychological improvements following exercise training. To satisfactorily test the exercise/cognition hypothesis with humans, carefully controlled intervention studies that last longer than those previously employed are needed.

Age-related decline of psychomotor speed: effects of age, brain health, sex, and education

A cross-sectional study into age-related decline of psychomotor speed is reported. A newly introduced choice response task was used, involving three conditions: simple reaction time (SRT), choice reaction time (CRT), and CRT with stimulus-response incompatibility. Subjects were 247 volunteers, aged 20 to 80 yr. in seven age levels. Although all subjects thought themselves to be normal and healthy, a post hoc division could be made based on biological life events (BLE, mild biological or environmental factors that can hamper optimal brain functioning, such as repeated general anesthesia). Performance was poorer by subjects who had experienced one or more such event: slowing was comparable to the effect of age, especially in the more difficult task conditions. There were significant effects of sex and education, men being consistently faster than women, and more highly educated subjects performing better than subjects with only low or medium education. These findings replicate observations from other test methods. They are also in line with several other studies giving interactions between the effects of aging and physical fitness. This study questions the validity of much research on aging, as the data suggest that a more rigorous health screening for biological life events in subjects recruited from the normal, healthy population can reduce performance effects normally ascribed to aging.

Reaction times with reference to musculoskeletal complaints in adolescence

Recent studies have related long reaction times and various musculoskeletal complaints in different groups of adults. The aim here was to analyze reaction times with reference to musculoskeletal complaints in adolescent athletes and controls. Simple reaction time and choice reaction time were measured, and inquiries made about various musculoskeletal injuries of 119 subjects aged 11 to 14 years. Gender, age, maturational age, body composition, and participation in sports were included in the analyses as subject-related factors affecting reaction times. Prolonged simple reaction time was related to low-back and lower extremity complaints in a two-way analysis of variance. The finding agreed with data of previous studies suggesting that slow psychomotor speed of reaction is associated with the outcome of musculoskeletal injuries.

Exercise performance of collegiate rodeo athletes

In this study we examined the physical, hematologic, and exercise response of 20 male and 10 female athletes of the National Intercollegiate Rodeo Association, Central Rocky Mountain Region. Male subjects were grouped by roughstock, steer wrestling, and roping events. Female athletes were grouped separately. Maximal aerobic capacity, pulmonary ventilation, respiratory exchange ratio, energy expenditure, maximal heart rate, blood pressure, treadmill time, pre- and postexercise lactate, percent body fat, lean body mass, blood chemistry, serum lipids, and reaction/movement time were analyzed by event. No significant differences (P greater than 0.05) were found in any of these categories between male events. Mean resting blood chemistry parameters of rodeo athletes were within normal ranges. Steer wrestling athletes possessed greater body size and lean body mass than other groups. When analyzing body composition, blood pressure, and total cholesterol:high-density lipoprotein (HDL) cholesterol ratios, results indicate average to low risk for coronary heart disease. When compared to other intermittent-activity sport athletes, college rodeo athletes appear to have similar aerobic capacities, but possess lower lean body mass and greater percent body fat.

Mobility impairment in the elderly: challenges for biomechanics research

The problems of mobility impairment in the elderly constitute new and major challenges for biomechanics research. This paper outlines what some of the important problems are, discusses the relevance of biomechanics research to these problems, and reviews some of the current state of knowledge about factors related to the biomechanics of mobility impairments in the elderly. The population of old adults is growing rapidly and the incidence of mobility impairments in old adults is high. Mobility impairment biomechanics research is needed to make the assessments of impairments more precise, to design therapeutic programs that are more effective and to learn more about how mobility impairments can be prevented.

Effects of age and sex on reciprocal tapping performance

Using a reciprocal tapping task (Fitts's task), the speed and accuracy of small-amplitude motor movements of the hand were measured for 62 men and 84 women, 20 to 89 yr. of age. Men and women in their 20s and 30s performed similarly, although men in their 20s displayed a tendency to trade accuracy in favor of speed. Movement time increased noticeably for both men and women beginning with the 40s decade and continued to increase through the 80s decade. Error rates were lower for women than men and were relatively uniform for both men and women across all age decades past 30 yr. Older subjects of both sexes appeared to sacrifice speed (slowed down) to maintain accuracy on the task. The slope of the linear regression relating movement time to task difficulty was steeper for men than for women and increased more for men than women with advancing age, indicating that older men slowed down relatively more than older women on more difficult tasks.