Group Of Healthy Older Adults Research Articles

Alterations in oculomotor behavior in healthy aging and mild cognitive impairment

Age-related changes in saccade behavior on short timescales (a few seconds) is often ascribed to changes in sensorimotor processing, working memory, or executive functioning. Visual exploration is additionally guided, at long timescales (minutes to hours), by memory representations supported by the hippocampal and broader medial temporal lobe system. Here, we examined whether age-related and neurodegenerative changes to the memory system impact more immediate saccade behavior by comparing the performance of younger adults (YA), healthy older adults (HOA), and older adults diagnosed with amnestic mild cognitive impairment (aMCI). 27 YA (18-35 years), 34 HOA (60-86 years) and 9 aMCI (46-84 years) performed a set of saccade tasks that systematically manipulated memory demands and the complexity of saccadic behaviour. A subset of tasks involved single saccades directed to a target 1) immediately (visually-guided task), 2) after a variable delay 500-1500 ms (gap), and 3) to a remembered location after a variable delay 300-3000 ms (memory-guided task). In another set of memory-guided tasks, participants directed saccades to two remembered targets in sequential and reverse order after a variable delay (double-step forward and backward). Using a multivariate partial least squares analysis, HOA and MCI groups were shown to have longer initial saccade latencies than YA in all but the visually-guided task. HOA and MCI initial saccade latencies did not differ significantly. Second saccade latencies in the double-step forward task were shorter for HOA than YA but longer for MCI as compared to the other two groups. Spatial errors did not differ across groups, suggesting that the differences in latencies were not due to differences in speed-accuracy tradeoffs across groups. Our results confirm previous findings of the impact of age-related changes in sensorimotor processing on saccade behavior. Our findings suggest that functional changes in the medial temporal lobe may affect oculomotor guidance on short timescales.

Odors Associated With Autobiographical Memory Induce Visual Imagination of Emotional Scenes as Well as Orbitofrontal-Fusiform Activation.

Specific odors can induce memories of the past, especially those associated with autobiographical and episodic memory. Odors associated with autobiographical memories have been found to elicit stronger activation in the orbitofrontal cortex, hippocampus, and parahippocampus compared with odors not linked to personal memories. Here, we examined whether continuous odor stimuli associated with autobiographical memories could activate the above olfactory areas in older adults and speculated regarding whether this odor stimulation could have a protective effect against age-related cognitive decline. Specifically, we used functional magnetic resonance imaging to investigate the relationship between blood oxygen levels in olfactory regions and odor-induced subjective memory retrieval and emotions associated with autobiographical memory in older adults. In our group of healthy older adults, the tested odors induced autobiographical memories that were accompanied by increasing levels of retrieval and the feeling of being “brought back in time.” The strength of the subjective feelings, including vividness of the memory and degree of comfort, impacted activation of the left fusiform gyrus and left posterior orbitofrontal cortex. Further, our path model suggested that the strength of memory retrieval and of the emotions induced by odor-evoked autobiographical memories directly influenced neural changes in the left fusiform gyrus, and impacted left posterior orbitofrontal cortex activation through the left fusiform response.

The association between sleep deficits and sedentary behavior in people with mild Parkinson disease

Purpose: Sleep deficits are a common nonmotor symptom of Parkinson disease (PD). People with mild PD also achieve less physical activity (PA) than healthy older adults (HOA), but the relationship between sleep and PA in PD is unclear. This study examined associations between sleep and PA in participants with PD and HOA. Materials and Methods: Secondary analysis of a prospective observational study. Participants wore a commercially available activity monitor for two weeks. Wilcoxon Rank-Sum tests compared nighttime sleep, wakenings after sleep onset, number of wakenings, naps, step count, and PA intensity between PD and HOA groups. Age-adjusted regression models calculated associations between nighttime sleep and PA. Results: Per day, participants with PD slept 75 fewer minutes (p < 0.01), took 5,792 fewer steps (p < 0.001), achieved less PA at all intensities, and had 32% more sedentary time (p < 0.001) compared to HOA. Thirty minutes more sleep was associated with 26 fewer sedentary minutes for HOA (p = 0.01) and 25 fewer sedentary minutes for the PD group (p < 0.001). Conclusions: Sleep and PA are reduced in mild PD compared to HOA. Both groups demonstrated similar associations between reduced sleep and increased sedentary behavior. Results may encourage providers to screen for sleep deficits when promoting PA. IMPLICATIONS FOR REHABILITATION The use of a wrist-worn commercial activity and sleep monitor was well tolerated by both healthy older adults and people with mild Parkinson Disease in this study. People with mild Parkinson Disease slept less and were less active than a group of healthy older adults. Less sleep was associated with more sedentary behavior in both groups. The relationship between poor sleep and sedentary behavior in mild Parkinson Disease suggests that rehabilitation interventions may be optimized by targeting both physical activity and sleep deficits.

Kinematic Analysis of Dance-Based Exergaming: A Cross-Sectional Study.

Recent studies demonstrate improvements in both postural stability and mobility among aging populations and those with stroke who are exposed to dance-based exergaming (DBExG). However, age-related deficits and aging with cortical pathology may lead to distinct movement adaptation patterns during DBExG, which could impact therapeutic outcomes.<br/> Aim: The aim of this study was to examine the movement kinematics (postural stability and mobility) of healthy older adults, older adults with stroke, and young adults for different paces of dance during DBExG.<br/> Method: The study included 33 particpants (11 participant from each group of healthy older adults, older adults with chronic stroke, and healthy young adults) who performed the DBExG using slow- (SP), medium- (MP), and fast-paced (FP) songs with movements in the anteroposterior (AP) and mediolateral (ML) directions. Center of mass (CoM) sway area, excursion (Ex), and peaks as well as hip, knee, and ankle joint excursions were computed.<br/> Results: Results of the study revealed that CoM sway areas and Exs were greater for healthy young adults than for older adults with stroke for the SP dance (p < 0.05) and that there were significantly more AP CoM peaks for young adults than for healthy older adults and those with stroke for the FP dance (p < 0.05). Young adults also exhibited greater hip and ankle Exs than older adults with stroke (p < 0.05) for all song paces. Similarly, knee and ankle Exs were greater for healthy older adults than for older adults with stroke for all song paces (p < 0.05).<br/> Conclusion: The quantitative evaluation and comparison of the movement patterns presented for the three groups could provide a foundation for both assessing and designing therapeutic DBExG protocols for these populations.

Binding objects to their spatiotemporal context: Age gradient and neuropsychological correlates of What-Where-When task performance

A number of recent studies have shown that the ability to accurately recall bound object and spatiotemporal aspects of an experienced event develops gradually in children and is greatly impaired in the elderly, reflecting developmental discontinuities in the integrity of the underlying medial temporal lobe network. Using a novel What-Where-When (WWW) visuospatial reconstruction task, the experiential memory performance of a group of healthy older adults (aged 60–80) was compared to that of a group of younger adults (aged 20–40). Both groups were equated on their general cognitive ability, their executive functioning, and on the presence of depression, anxiety, and stress symptomatology. As hypothesized, the performance of the older adults in the binding task was significantly lower, with younger participants recalling three times the amount of bound object and spatiotemporal triads than their older counterparts. Psychomotor speed was found to be lower in older adults and was the only neuropsychological index to significantly affect success on the WWW binding task. Based on this and other relevant studies, the selective associative memory impairment obtained using a non-verbal What-Where-When paradigm emerges as a marker for the detection of early pre-clinical signs of experiential memory pathology.

Validation of the Coin in Hand-Extended Version Among Older Adults With and Without Dementia.

The current study aimed to validate the Performance Validity Test Coin in Hand-Extended Version (CIH-EV) in groups of healthy older adults and older adults with dementia. Using an analog simulation paradigm, the healthy control group and the clinical group were instructed to perform to the best of their ability, whereas the feigning older adults were instructed to simulate a memory deficit to obtain allowance, financial aid, or early retirement. Results showed that the control and clinical groups performed more optimally than the feigning group, although the clinical group had superior response times. The CIH-EV was insensitive to sociodemographic variables and neurocognitive functioning in all groups, demonstrated good convergent validity with other performance validity measures, and showed a reduced rate of false positives. This study corroborates the CIH-EV's effectiveness in detecting the simulation of cognitive deficits in healthy older adults and older adults with dementia.

A newly developed amnestic subjective cognitive decline questionnaire shows high internal consistency and inter‐rater reliability

AbstractBackgroundSubjective cognitive decline (SCD) represents a state in which a participant perceives a decline in cognitive functions, yet standardized psychological tests remain within expected performance compared to age‐ and education‐matched controls. SCD is growingly recognized as a risk state for mild cognitive decline (MCI), and eventually, dementia. In this study, we introduce a newly developed Amnestic Subjective Cognitive Decline questionnaire (aSCDq), an instrument with four screening and five severity items (Table 1). We present preliminary internal consistency and inter‐rater reliability results.MethodWe analyzed the clinimetric data from 52 older adults (age 67.2 ±4.4 years), 9 diagnosed with amnestic Mild Cognitive Impairment (MCI), 16 with amnestic Subjective Cognitive Decline (aSCD), and 27 healthy older adults (HOA). We used polychoric correlation matrixes in a principal component analysis to assess the internal consistency of the four screening items, and to analyze the correlation between subject and informant response in all items.ResultHigh internal consistency was found regarding the four screening items, resulting in a single component with an eigenvalue of 3.3, and 0.83 explained variance. High inter‐rater correlations in all screening items were found (1: 0.9, 2: 0.8, 3: 0.5, 4: 0.7), with more variable correlations demonstrated in severity items (s1: 0.3, s2: 0.5, s3: 0.7, s4: 0.9, s5: 0.6). Higher scores (i.e. worst memory complaints) were consistently reported by subjects in HOA and aSCD groups, and by informants in the MCI group.ConclusionBased on these preliminary results, the aSCDq has been shown to be a consistent and reliable tool to determine aSCD in older adults. The inter‐rater differences are slight but consistent with previous literature. For a full validation of this instrument, a higher number of participants will be necessary.

Conflict monitoring on an emotional Stroop task. Comparison of healthy older adults and patients with major neurocognitive disorders due to probable AD

ABSTRACT Introduction The conflict monitoring system exerts an influence on centers responsible for cognitive control, causing them to intervene more strongly in processing when conflict occurs. These mechanisms are usually investigated through specific tasks where there is an inherent interference elicited by the congruency or incongruency between the stimuli and responses, such as the Stroop task. In studies of emotional conflict, one hypothesis related to the dorsal anterior cingulate cortex (ACC) is that it serves, in part, to signal the appearance of conflicts, thus triggering compensatory adjustments. This study aims to verify whether the conflict monitoring hypothesis is confirmed in a group with Alzheimer’s disease and, therefore, whether they exhibit a reduction in their reaction times. Method A group of healthy older adults (HOA) and a group with Major Neurocognitive Disorders due to probable AD were evaluated to test the conflict monitoring hypothesis with an emotional Stroop task. Results A significant interaction was obtained on the word and faces blocks. In the HOA group, a reduction in reaction times was observed, whereas in the AD groups, no reduction in reaction times was obtained. Conclusions Whereas in HOA the conflict monitoring hypothesis is confirmed, in the Major Neurocognitive Disorders due to probable AD group there is no reduction in their reaction times on the high conflict resolution trials (incongruent trials that follow incongruent trials) due to their difficulty in making compensatory adjustments to cognitive control that help them to reduce conflict and improve their success rate.

RELATIONSHIP BETWEEN CHOLINERGIC RECEPTOR BINDING AND ATTENTION IN COGNITIVE AGING USING POSITRON EMISSION TOMOGRAPHY AND THE STROOP

Introduction Cholinergic (Ach) neurotransmission has been associated with aspects of brain attention networks. Reductions in Ach are also thought to underlie cognitive symptoms in Alzheimer's Disease (AD). In a previous study using positron emission tomography (PET) imaging to measure nicotinic Ach receptor binding in vivo, our group found that Ach receptor binding was reduced in patients with AD relative to healthy controls. Reductions were observed in areas of the brain thought to mediate attention, including the anterior cingulate cortex/medial prefrontal cortex (ACC/mPFC) and insula. The Stroop is a neuropsychological measure used in research and clinical settings to assess attention and executive function. In a different study of AD patients, we found that performance on the Stroop was associated with metabolic activity in brain networks in the right hemisphere; the Stroop COLOR-WORD condition was associated with metabolic rate in the intraparietal sulcus (IPS), ACC/mPFC, and insula. In the present study, we sought to extend these findings by examining whether Ach binding was associated with performance on the Stroop prior to the onset of dementia. Methods The study included a combined group of healthy older adults or older adults with amnestic mild cognitive impairment (MCI). All participants completed the Stroop. The Stroop included three conditions: two simpler tasks requiring participants to name colors (COLOR) and read words (WORD) and a more complex task in which participants are required to name the color of ink used for a word that names a different color from the ink color (COLOR-WORD). Cholinergic (Ach) receptor binding was quantified using PET imaging, specifically 18F-2-FA PET (2FA), a radiotracer that binds to alpha4beta2 nicotinic receptor subunits. Scanning utilized a bolus plus infusion technique and measurement of nonmetabolized 2FA from plasma to calculate distribution volume (VT/fp) in PET Ach image voxels. Ach images were pre-processed using SPM12, which included motion correction, normalization to Montreal Neurological Institute (MNI) space using a co-registered T1 MRI image, and spatial smoothing of 8?mm full width at half maximum. First, a voxel-based analysis across the entire brain was used to measure the association between voxel VT/fp and performance on the Stroop COLOR-WORD test using a liberal statistical threshold (p Results Seventy-six participants were included in the sample, comprised of 43 healthy older adults and 33 patients with amnestic MCI (age: mean=73.1 (SD=7.7), MMSE: mean=28.3 (SD=2.1), 57 males and 19 females, education: mean=15.7?years (SD=2.5)). The combined group included 19 African-Americans, 48 Caucasians, 6 Hispanics, and 3?Asian/?Pacific Islanders. Performance on the COLOR task was associated with mean VT/fp in the ACC/mPFC (r=.23 p=.04), insula (r=.28, p=.02), and IPS (r=.23 p Conclusions Across the spectrum of cognitive aging, performance on the Stroop was associated with Ach binding in key brain regions involved in attention—the IPS, ACC/mPFC, and insula. These findings suggest that Ach binding, in part, mediates attentional processing. This appears true regardless of whether the task is simple, as in the COLOR and WORD conditions, or more complex, as in the COLOR-WORD condition. Thus, changes in Ach receptor binding may be an important factor in attentional deficits resulting from cognitive aging prior to onset of AD, and Ach neurotransmission could be a potential molecular target for novel pharmaceuticals to address these symptoms. This research was funded by: This work was supported by a VA Career Development grant awarded to Brandon C. Yarns, MD, MS, and VA Merit Review grants awarded to David L. Sultzer, MD, and Rebecca J. Melrose, PhD.

Drawing pictures at encoding enhances memory in healthy older adults and in individuals with probable dementia

ABSTRACT We explored the efficacy of drawing pictures as an encoding strategy to enhance memory performance in healthy older adults and individuals with probable dementia. In an incidental encoding phase, participants were asked to either draw a picture or write out each word from a set of 30 common nouns for 40 seconds each. Episodic memory for the target words was compared in a group of healthy older adults to individuals with probable dementia (MMSE/MOCA range 4 to 25). In two experiments we showed that recall and recognition performance was higher for words that were drawn than written out during encoding, for both participant groups. We suggest that incorporating visuo-perceptual information into memory enhanced performance by increasing reliance on visual-sensory brain regions, which are relatively intact in these populations. Our findings demonstrate that drawing is a valuable technique leading to measurable gains in memory performance for individuals with probable dementia.

The plasma metabolome as a predictor of biological aging in humans

Chronological age is an important predictor of morbidity and mortality; however, it is unable to account for heterogeneity in the decline of physiological function and health with advancing age. Several attempts have been made to instead define a "biological age" using multiple physiological parameters in order to account for variation in the trajectory of human aging; however, these methods require technical expertise and are likely too time-intensive and costly to be implemented into clinical practice. Accordingly, we sought to develop a metabolomic signature of biological aging that could predict changes in physiological function with the convenience of a blood sample. A weighted model of biological age was generated based on multiple clinical and physiological measures in a cohort of healthy adults and was then applied to a group of healthy older adults who were tracked longitudinally over a 5-10-year timeframe. Plasma metabolomic signatures were identified that were associated with biological age, including some that could predict whether individuals would age at a faster or slower rate. Metabolites most associated with the rate of biological aging included amino acid, fatty acid, acylcarnitine, sphingolipid, and nucleotide metabolites. These results not only have clinical implications by providing a simple blood-based assay of biological aging, but also provide insight into the molecular mechanisms underlying human healthspan.

Pharyngeal Area Changes in Parkinson's Disease and Its Effect on Swallowing Safety, Efficiency, and Kinematics.

Pharyngeal area can increase as a function of normal healthy aging and muscle atrophy. These increases in pharyngeal area can negatively affect swallowing function in healthy older adults (HOA). However, the presence of pharyngeal area changes and their effects on swallowing function in Parkinson's disease (PD) remain unknown. Therefore, we compared the pharyngeal area of people with PD to HOA to determine if pharyngeal area changes were present in PD above and beyond what is seen in HOA. Within PD, we also evaluated if and how an increase in pharyngeal area affects swallowing kinematics, swallowing safety, and swallowing efficiency. A secondary analysis of videofluoroscopic swallow studies was completed comparing 41 HOA and 40 people with PD. Measures of pharyngeal area, swallowing kinematics, swallowing safety (penetration/aspiration), and swallowing efficiency (residue) were analyzed. An analysis of covariance (ANCOVA) was used to determine if pharyngeal area was significantly different between the HOA and PD groups while controlling for age, sex, and height. Regression analyses were used to examine if and how pharyngeal area influenced swallowing kinematics, swallowing safety, and swallowing efficiency in PD. Pharyngeal areas were significantly larger for people with PD when compared to HOA (p = .008). An increase in pharyngeal area was associated with less pharyngeal constriction (p = .022), shorter duration of airway closure (p = .017), worse swallowing safety (p < .0005), and worse swallowing efficiency (p = .037). This study revealed that pharyngeal areas are larger in people with PD when compared to HOA, and that this increase in pharyngeal area is associated with maladaptive changes to swallowing kinematics, residue, and penetration/aspiration. These findings support the notion that pharyngeal muscle atrophy may be exacerbated in PD above and beyond what is seen in normal, healthy aging group. Results from this study highlight the need to consider pharyngeal muscle atrophy as a source for swallowing dysfunction in PD, and as a potential treatment target for swallowing rehabilitation.

Quantifying physical activity in early Parkinson disease using a commercial activity monitor

IntroductionPhysical inactivity in Parkinson disease (PD) has an impact on motor and non-motor symptoms of the disease. It is unclear whether this decline in physical activity occurs early in the disease, in addition to any decline due to aging, and whether commercial activity monitors can be used to self-monitor physical activity levels in this population. ObjectiveTo compare the quantity and intensity of physical activity (PA), as measured by commercial activity monitors, in people with mild PD and healthy older adults (HOA). A secondary objective was to assess adherence and user experience with wearing the activity monitoring device. MethodsAn observational descriptive study design examined PA levels over a 14-day period using commercially-available activity monitors (Fitbit Charge HR). ResultsIndividuals with PD (n = 30) and HOA (n = 30) both demonstrated high adherence with wear time (PD = 13.8 [0.5] days, HOA = 13.9 [0.4] days, p = 0.55). People with PD took fewer steps per day than HOA (PD = 6416.9 (2795.5), HOA = 11441.3 (3932.1), p < 0.001). Compared to HOA, individuals with PD spent fewer minutes per day engaged in moderate to vigorous intensity activity (PD = 33.0 (22.5), HOA = 72.0(37.3), p < 0.001) and more minutes per day sedentary (PD = 803.74 (154.9), HOA = 578.26 (103.7), p < 0.001). Both groups reported that ease of use and satisfaction with the activity monitor were high. ConclusionsPeople with mild PD demonstrated reduced quantity and intensity of PA compared to HOA. Both the PD and the HOA groups had good adherence wearing a commercial activity monitor that provided feedback regarding activity levels.

Enhancement of posterior brain functional networks in bilingual older adults

AbstractBilingualism has been said to improve cognition and even delay the onset of Alzheimer's disease (AD). This research aimed to investigate whether bilingualism leaves a neurophysiological trace even when people are highly educated. We expected bilinguals to present better preserved brain functional networks, which could be a trace of higher cognitive reserve. With this purpose, we conducted a magnetoencephalographic study with a group of healthy older adults. We estimated functional connectivity using phase-locking value and found five clusters in parieto-occipital regions in which bilinguals exhibited greater functional connectivity than monolinguals. These clusters included brain regions typically implicated in language processing. Furthermore, these functional changes correlated with caudate volumes (a key region in language shifting and control) in the bilingual sample. Interestingly, decreased Functional Connectivity between posterior brain regions had already been identified as an indicator of aging/preclinical AD but, according to our study, bilingualism seems to exert the opposite effect.

Naturalistic assessment of task interruption in individuals with mild cognitive impairment.

Interruptions are ubiquitous in everyday life, and recovering from interruptions requires several cognitive processes working in tandem. In this study, we assessed the effects of an interruption on the performance of older individuals with and without mild cognitive impairment (MCI) completing everyday tasks in a naturalistic apartment setting. Thirty-two persons with MCI and 64 cognitively healthy older adults (HOA) completed two different sets of everyday activities, of which one received an interruption. Participants also completed tests assessing cognitive constructs thought to be important in interruption recovery including retrospective memory, prospective memory, planning, working memory, and executive function. As a consequence of an interruption, participants with MCI took longer to complete primary task demands and made more substitution errors, but did not make more omission errors. In contrast, an interruption led HOAs to make more omission errors, but their time on task was not affected. Results from a hierarchical linear regression suggest that the ecologically valid interruption task time was more predictive of everyday functional status than the traditional neuropsychological measures. Results suggest that a brief task interruption taxed cognitive resources of both MCI and HOA groups, but was more detrimental to MCI in terms of time on task and total errors committed. Participant groups appeared to use a speed-accuracy trade-off to mitigate negative effects, where HOAs emphasized speed and MCI participants focused on accuracy. Amount of cognitive engagement/disengagement was also theorized to have played a role, where MCI may have maintained information online throughout the interruption, and HOAs disengaged and reengaged resulting in worse reactivation of goals. Although MCI held onto task goals, their execution of details was imperfect over the interruption delay resulting in substitution errors likely due to further taxed executive abilities. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Can Daytime Napping Assist the Process of Skills Acquisition After Stroke?

Acquisition and reacquisition of skills is a main pillar of functional recovery after stroke. Nighttime sleep has a positive influence on motor learning in healthy individuals, whereas the effect of daytime sleep on neuro-rehabilitative training and relearning of the trained skills is often neglected. The aim of this study was to investigate the relationship between daytime sleep (napping) and the ability to learn a new visuomotor task in chronic stroke patients. The main hypothesis was that sleep enhances motor memory consolidation after training resulting in better motor performance after a period of daytime sleep. Thirty stroke survivors completed the study. They were randomized to one of three different conditions (i) wakeful resting, (ii) short nap (10–20 min), or (iii) long nap (50–80 min). All individuals trained the task with the contralesional, stroke-impaired hand, behavioral evaluation was performed after the break time (wake, nap), and 24 h later. Patients demonstrated a significant task-related behavioral improvement throughout the training. In contrast to the main hypothesis, there was no evidence for sleep-dependent motor consolidation early after the initial, diurnal break, or after an additional full night of sleep. In a secondary analysis, the performance changes of stroke survivors were compared with those of a group of healthy older adults who performed the identical task within the same experimental setup with their non-dominant hand. Performance levels were comparable between both cohorts at all time points. Stroke-related difficulties in motor control did not impact on the degree of performance improvement through training and daytime sleep did not impact on the behavioral gains in the two groups. In summary, the current study indicates that one-time daytime sleep after motor training does not influence behavioral gains.

Altered muscle synergies during gait in individuals with knee osteoarthritis

Purpose: While there are well documented differences in gait between symptomatic knee osteoarthritis (OA) as compared to healthy older adults the mechanism for how these altered movement patterns occur are not well characterized. Quantification of synergistic muscle activation patterns in knee OA may provide insight to the altered control of movement that may result from joint pain, inactivity, or changes in joint structure, and contribute to the decline in physical function. It has been proposed that movement may be controlled through synergistic activation of muscle groups working as a single functional unit. Quantification of these groupings (aka muscle synergies) can provide insight into neural control of movement by describing not only which muscles are coactivating, but also how they work together to carry out functional movements. In both cerebral palsy and stroke, fewer synergies were needed to describe movements, compared to healthy or unaffected limbs, suggesting a simplified control pattern due to co-contraction. In addition, differences found in the make-up of the muscle synergies throughout movement tasks suggest less coordinated movement with more severe pathologies. The purpose of our study is to quantify differences in muscle synergies between individuals with symptomatic knee OA and healthy older adults. We hypothesize that due to cocontraction, there will be fewer muscle synergies in individuals with knee OA compared to healthy older adults, and that the contribution of these synergies will differ throughout the gait cycle. Methods: After IRB approval, 17 healthy older adults (HA) and 17 symptomatic knee OA were enrolled. Participants walked on a treadmill at a preferred pace and following a 2 minute warm-up EMG was collected at 2000 Hz on 8 leg muscles. EMG signals were then filtered, rectified, and normalized to the gait cycle for 9 total strides for each individual. Mean data for each individual was then concatenated to form one group matrix for OA and one for HA in order to account for individual characteristics within groups in synergy analysis. Muscle synergies were extracted using non-negative matrix factorization (NMF) in both HA and OA. Variance accounted for (VAF = 1-SSE/SSTE) was calculated to determine the number of synergies needed to describe >90% of variance in muscle activation and used to test for differences in complexity of movement between groups. Differences in the contribution of individual muscles to each synergy was determined via visual inspection and then the activation of similar synergies at 0, 30, and 66% of the gait cycle (approx. heel-strike(HS), peak knee flexion(pKF), and toe-off(TO) respectively) were compared using one-way ANOVA's. Results: To account for >90% variability, 4 synergies were needed in the OA group (VAF = 93.4%), while only 3 were needed in the HA group (VAF = 92.4%). In order to easily compare between groups 4 synergies were used to describe both OA and HA (VAF = 96.9%). At HS, activation of synergy C (Fig.1) for OA (0.10 ± 0.21) was significantly higher compared to HA (0.06 ± 0.04, P = 0.001). At pKF, activation of synergy B was significantly higher in OA (0.08 ± 0.04) compared to HA (0.05 ± 0.02, P = 0.010). No difference was found between activation of synergies at TO. Conclusions: In contrast to our hypothesis a greater number of synergies were needed to account for >90% variance in the EMG for the OA group compared to the HA group, suggesting that control patterns in OA are not less complex. The differences in the contributions of the VL, VM and MH to synergy B along with greater activations of synergies B and C at pKF and HS respectively in OA suggests in agreement with the hypothesis that there is greater co-activation of the quadriceps and hamstrings in gait. A strong synergistic relationship between the quadriceps and hamstrings in OA may be related to either pain or joint instability and warrants further analysis to understand the contributing factors.

Sentence Context and Word-Picture Cued-Recall Paired-Associate Learning Procedure Boosts Recall in Normal and Mild Alzheimer's Disease Patients.

Introduction The aim of this study was to employ the word-picture paradigm to examine the effectiveness of combined pictorial illustrations and sentences as strong contextual cues. The experiment details the performance of word recall in healthy older adults (HOA) and mild Alzheimer's disease (AD). The researchers enhanced the words' recall with word-picture condition and when the pair was associated with a sentence contextualizing the two items. Method The sample was composed of 18 HOA and 18 people with mild AD. Participants memorized 15 pairs of words under word-word and word-picture conditions, with and without a sentence context. In the paired-associate test, the first item of the pair was read aloud by participants and used to elicit retrieval of the associated item. Results The findings suggest that both HOA and mild-AD pictures improved item recall compared to word condition such as sentences which further enabled item recall. Additionally, the HOA group performs better than the mild-AD group in all conditions. Conclusions Word-picture and sentence context strengthen the encoding in the explicit memory task, both in HOA and mild AD. These results open a potential window to improve the memory for verbalized instructions and restore sequential abilities in everyday life, such as brushing one's teeth, fastening one's pants, or drying one's hands.

Differences in chunking behavior between young and older adults diminish with extended practice

Previous research found reduced motor chunking behavior in older adults compared to young adults. However, it remains unclear whether older adults are unable to use a chunking strategy or whether they are just slower in developing them. Our goal was to investigate the effect of extended practice on the development of chunking behavior in healthy older adults. A group of young and a group of healthy older adults between 74 and 85 years of age visited the lab on 2 days. A sequence of 3 and a sequence of 6 elements were both practiced 432 times in a discrete sequence production task. We found that age differences in chunking behavior, as measured by the difference between initiation and execution of the sequence, diminish with extended practice. Furthermore, in older, but not in young adults, slow responses that are often interpreted as the first response of a next motor chunk were associated with a finger that was also slow during performance of the random sequences. This finding calls for more attention to biomechanical factors in future theory about aging and sequence learning.

Can there be learning potential in Parkinson’s disease? A comparison with healthy older adults

ABSTRACTPatients with Parkinson’s disease may show certain cognitive impairments, although it is unclear how these deficits can affect their learning potential. The study aims to use the testing-the-limits technique to compare the potential for cognitive plasticity in a group of Patients with Parkinson’s disease (N = 33) and a group of healthy older adults (N = 33). Sixty-six participants performed verbal learning test to analyze the learning potential. Repeated-measures analysis of variance showed significant main effects of time, group, and the interaction. There is a lower learning potential in subjects with Parkinson’s disease; however, those still maintain a certain capacity for learning and, therefore, for cognitive plasticity.