Impoverished Inhibitory Control Exacerbates Multisensory Impairments in Older Fallers

Sound-induced flash illusion (SiFI) refers to an auditory dominance effect in which observers misperceive the number of visual flashes due to the simultaneous presentation of a different number of auditory beeps. Although the SiFI remains robust despite many factors, little is known about how the dominance of audition over vision changes as a function of spatial location in 3D space and how this corresponds with aging. In the present study, we recruited younger (18-26 years old) and older adults (60-76 years old) and presented visual stimuli in near space and auditory stimuli in far space (Vnear_Afar) or visual stimuli in far space and auditory stimuli in near space (Vfar_Anear), with the aim of exploring the effect of aging on spatial dominance in SiFI. The results showed that both participant groups exhibited a SiFI auditory dominance effect; however, older adults were more susceptible to illusions than younger adults. More importantly, for younger adults, when auditory stimuli were presented in far space, the accuracy and d' indicated that SiFI was significantly enhanced in the fission illusion, and the reaction time (RT) results showed that RT became longer in the fusion illusion. However, for older adults, the SiFI was not affected by the spatial location. Therefore, the present results reveal for the first time that the SiFI effect is modulated by the depth of auditory stimuli. Moreover, older adults were not susceptible to the depth dimension, thus showing age-related sensory decline and specifically showing a decreased ability to localize visual and auditory stimuli.

This study used a dual task design to investigate the effects of two different types of cognitive tasks on stability (as measured by center of pressure displacement) in young vs older adults with and without a history of falls. Two secondary cognitive tasks, a sentence completion and a visual perceptual matching task, were used to produce changes in attention during quiet stance under flat vs compliant surface conditions in 20 healthy young adults, 20 healthy older adults, and 20 older adults with a history of imbalance and falls. Postural stability was quantified using forceplate measures of center of pressure (COP). Speed and accuracy of verbal response on the cognitive tasks were also quantified. During the simultaneous performance of a cognitive and postural task, decrements in performance were found in the postural stability measures rather than the cognitive measures for all three groups. While no differences were found between the young adults and the older healthy adults on the firm surface, no task condition, when task complexity was increased (either through the introduction of a secondary cognitive task, or a more challenging postural condition such as standing on the compliant surface), significant differences in postural stability between the two groups became apparent. In contrast to the young and healthy older adults, postural stability in older adults with a history of falls was significantly affected by both cognitive tasks. Results suggest that when postural stability is impaired, even relatively simple cognitive tasks can further impact balance. Results further suggest that the allocation of attention during the performance of concurrent tasks is complex; depending on many factors including the nature of both the cognitive and postural task, the goal of the subject and the instructions.

Sustained integration of sensory inputs over increased temporal delays is associated with reduced cognitive and physical functioning in older adults and adverse outcomes such as falls. Here, we explored the relationship between multisensory integration and a clinically relevant measure of balance/postural control; Sit-to-Stand Time, the efficiency with which an older adult can transition between a seated and a standing posture. We investigated whether temporal multisensory integration was associated with performance on the Five-Times Sit-to-Stand Test (FTSST) in a large sample of 2556 older adults (mean age = 63.62 years, SD = 7.50; 55% female) drawn from The Irish Longitudinal Study on Ageing (TILDA). K-means clustering was applied to FTSST data, yielding three clusters characterised by fast (mean = 10.88 s; n = 1122), medium (mean = 14.34 s; n = 1133) and slow (mean = 18.97 s; n = 301) sit-to-stand times. At wave 3 of TILDA, older adults participated in the Sound Induced Flash Illusion (SIFI), a measure of the precision of temporal audio–visual integration, which included three audio–visual stimulus onset asynchronies (SOAs): 70, 150 and 230 ms. Older adults with the slowest sit-to-stand times were more susceptible to the SIFI at the longest SOA (230 ms) compared to the shortest SOA (70 ms) relative to those with the fastest times (p = 0.02). Older adults who take longer to repeatedly transition from a seated to a standing posture exhibit an expanded temporal binding window for audio–visual events, supporting a link between multisensory perception and balance/postural control in ageing.

Purpose: This study assessed the relationships between strength and ambulatory function, and balance and ambulatory function in community-dwelling older adults. Subjects: One hundred adults over the age of 65, with or without a history of 2 or more falls in the previous year, participated. Method: Measurements from hand-held dynamometry of ankle dorsiflexion strength, the Berg Functional Balance Scale, and the Timed Up and Go (ambulatory function) were collected. Data Analysis: Pearson correlations were used to analyze the data. Results: The correlation between balance and ambulatory function was moderate for the nonfaller (r = −0.574, p < 0.001) and faller (r = −0.611, p < 0.001) groups. A t-test between the r-coefficients revealed no significant difference in this relationship between the 2 groups. In both groups, the correlations between ankle strength and ambulatory function were weak. Conclusion: The moderate relationship found between balance and ambulatory function in older adults with or without a fall history suggests that assessment of balance may be a more predictive tool for screening fall risk and functional decline than ankle strength measurement.

Though some studies suggest that older adults are not differentially impacted by foreign-accented speech relative to younger adults, other studies indicate that older adults are poorer at perceiving foreign-accented speech than younger adults. The present study sought, first, to clarify the extent to which older and younger adults differed in their perception of foreign-accented speech. The secondary aim was to elucidate the extent to which the cognitive mechanisms supporting accented speech perception differ for older and younger adults. The data indicated that older adults were poorer at perceiving accented speech than younger adults. Older adults' speech perception accuracy was associated with a significant main effect of working memory as well as significant interactions between hearing acuity and cognitive flexibility and between hearing acuity and inhibitory control. Younger adults' speech perception accuracy, in contrast, was associated with a significant interaction between hearing acuity and processing speed. It therefore appears that the differences in performance between younger and older adults observed here may be attributable to differences in the cognitive mechanisms that support accented speech perception.

A better understanding of the impact of lifestyle factors on cognitive function in older adults is critical for developing intervention strategies to achieve successful aging. Moreover, older adults who fulfill the World Health Organization criteria for anemia have a significantly higher risk of developing dementia. In the current study, we aimed to assess the buffering effects of lifestyle on cognitive function in older Chinese adults through a nationally representative survey. The sample consisted of 1201 participants (mean age: 82.39 ± 12.08 years, 52.1% female) from the 2011/2012 and 2014 waves of the Chinese Longitudinal Healthy Longevity Survey. Multiple linear regression analyses were used to explore the relationship between changes in lifestyle factors and the rate of cognitive function changes, as well as the effects of the interaction between lifestyle factors and anemia on cognitive function changes. Increased levels of participation in leisure activities, social activities, and dietary diversity delayed cognitive decline. Persistent anemia accelerated cognitive decline, while frequent participation in leisure activities delayed cognitive decline due to anemia. The increased levels of participation in leisure activities, social activities, and dietary diversity can alleviate the cognitive decline caused by aging itself, and more frequently participation in leisure activities can also alleviate the adverse effects of anemia on cognitive function in older adults.

Objective24-h activity encompasses four categories: light-intensity physical activity (LPA), moderate-to-vigorous-intensity physical activity (MVPA), sedentary behavior (SB), and sleep (SP). This study aims to investigate the effects of different physical activity components on executive function in older adults with chronic diseases and to examine substitution effects among activity components. The findings provide scientific evidence to inform physical activity interventions for improving executive function in older adults with chronic diseases.MethodsA total of 105 older adults (72.64 ± 6.82 years) were recruited. Following questionnaire screening, 75 older adults with chronic diseases were ultimately included. Accelerometers objectively measured participants’ daily SP, SB, LPA, and MVPA. Executive function was objectively assessed using the Stroop task, N-back task, and More-odd-shifting task. Component linear regression equation assessed the relationship between different activities and executive function in older adults with chronic diseases. The dose–response effects of “one-for-one” substitutions between different activity behaviors were explored.ResultsComponent linear regression results showed that SB positively correlated with inhibitory control (β = 0.892, 95% CI = 0.044 to 1.741) and working memory (β = 1.610, 95% CI = 0.801 to 2.420). MVPA was negatively correlated with inhibitory control (β = −0.596, 95% CI = −1.156 to −0.036), while LPA was negatively correlated with working memory (β = −0.969, 95% CI = −1.812 to −0.127). No significant association with cognitive flexibility was found (p > 0.05). Isotemporal substitution results showed that for inhibitory control, replacing SB with SP for 30 min reduced z-scores by 0.068; replacing SB with MVPA for 30 min reduced z-scores by 0.285. For working memory, replacing SB with LPA every 30 min resulted in a z-score decrease of 0.152. Dose–response curves indicated that progressively increasing the proportion of time spent in SP and MVPA improved inhibitory control, while increasing LPA enhanced working memory.ConclusionSP and MVPA significantly improve inhibitory control in older adults with chronic diseases, while LPA significantly enhances their working memory. It is recommended that older adults with chronic diseases adjust their daily time structure by increasing diverse physical activities, ensuring adequate sleep duration, and reducing sedentary behavior to improve executive function.

The present study examined age-related differences in multisensory integration and the effect of spatial disparity on the sound-induced flash illusion—-an illusion used in previous research to assess age-related differences in multisensory integration. Prior to participation in the study, both younger and older participants demonstrated their ability to detect 1–2 visual flashes and 1–2 auditory beep presented unimodally. After passing the pre-test, participants were then presented 1–2 flashes paired with 0–2 beeps that originated from one of five speakers positioned equidistantly 100cm from the participant. One speaker was positioned directly below the screen, two speakers were positioned 50cm to the left and right from the center of the screen, and two more speakers positioned to the left and right 100cm from the center of the screen. Participants were told to report the number of flashes presented and to ignore the beeps. Both age groups showed a significant effect of the beeps on the perceived number of flashes. However, neither younger nor older individuals showed any significant effect of spatial disparity on the sound-induced flash illusion. The presence of a congruent number of beeps increased accuracy for both older and younger individuals. Reaction time data was also analyzed. As expected, older individuals showed significantly longer reaction times when compared to younger individuals. In addition, both older and younger individuals showed a significant increase in reaction time for fusion trials, where two flashes and one beep are perceived as a single flash, as compared to congruent single flash trials. This increase in reaction time was not found for fission trials, where one flash and two beeps were perceived as two flashes. This suggests that processing may differ for the two forms for fission as compared to fusion illusions.

Baseline data are reported from a study of the effects of zinc supplementation on cognitive function in older adults as assessed by the CANTAB computerised test battery. This is a multicentre prospective intervention study employing a randomised double-blind design. European community-based study. There are 387 healthy adults aged 55-87 y from centres in France, Italy and Northern Ireland. Measures of visual memory, working memory and attention were obtained at baseline (prior to supplementation). Younger adults (<70 y) performed significantly better than older adults (>70 y) on all tests, with minimal differences between centres. In addition, men outperformed women on tests of spatial span, pattern recognition memory and reaction times, although these gender differences varied somewhat between centres. The results are generally consistent with previous age- and gender-related effects on cognitive functioning.

BackgroundThyroid function may be a factor affecting kidney function in the general population. Kidney and thyroid function vary with age; therefore, the association between thyroid function and decreased kidney function in older adults may be different from that in younger adults and remains controversial. This study aimed to estimate the association between normal-range thyroid function and age-related decline in kidney function in older Chinese adults.MethodsA total of 15,653 adults, of whom 23.2% (N = 3624) were older adults (age≧65 years), were collected at the Health Management Center of the First Affiliated Hospital of Nanjing Medical University from January 2018 to January 2020. Basic demographic information was collected by a physician-administered questionnaire. The estimated glomerular filtration rate (eGFR) was calculated using the CKD-EPI formula. Trends in thyroid function with age were shown by means of free triiodothyronine (FT3), free thyroxine (FT4), and thyroid-stimulating hormone (TSH) in subgroups every ten years. The association between kidney function and thyroid function was estimated by multiple linear regression using β value and by multivariable logistic regression models using odds ratios (OR) after adjusting for age, gender, body mass index, and serum urine acid.ResultsIn the older population, TSH tended to increase with age and FT3 tended to decrease, whereas FT4 was relatively stable. eGFR decreased significantly with increasing TSH (β = -0.081) and decreasing FT3 (β = 0.083) concentrations. Compared with those in the lowest quartile of FT3 (3.10–4.47 pmol/L), the prevalence of eGFR < 75 ml/min/1.73m2 decreased significantly by 22.0% for those with FT3 of 4.47–4.81 pmol/L, 27.6% for those with FT3 of 4.82–5.20 pmol/L, and 34.9% for those with FT3 of 5.21–6.8 pmol/L in older individuals (P for trend < .001). The OR was 1.315 (P: 0.025) in subjects with high-normal TSH, using low-normal TSH as a reference. The prevalence of reduced kidney function was not significantly associated with FT4 within the reference range. Similar results were found in association between the prevalence of eGFR < 60 ml/min/1.73m2 and thyroid function.ConclusionsThis study demonstrated a significant association between kidney function and thyroid function, particularly FT3, in the older population. Clinicians may need to pay more attention to the assessment and follow-up of kidney function in older individuals with low-normal FT3 and high-normal TSH.

Vitamin D insufficiency contributes to muscle weakness and a higher risk of falls in older adults. This study explored the impact of vitamin D supplementation on self-reported falls and physical function in older adults with low vitamin D levels and a recent fall history. Twenty-five older adults ≥ 70 years with two or more falls during the past year, low vitamin D blood levels (≥10 ng/ml and < 30 ng/mL), and slow gait speed (1.2 m/s) participated in a 6-month vitamin D supplementation (800 IU/day) study. A modified version of the Morse Fall Scale questionnaire was used to assess frequency of falls over one-year prior to study enrollment. Functional outcomes (short physical performance battery, handgrip strength, gait Timed Up and Go, and six-minute walk), and vitamin D levels were assessed at baseline and 6-month follow-up. Based on diaries and pill counts, participants were generally adherent to the intervention (6 of 7 days per week). Supplementation with 800 IU/day of vitamin D for 6 months increased blood vitamin D levels from 23.25±4.8 ng/ml to 29.13±6.9 ng/ml (p<0.001). Self-reported number of falls decreased from an average of 3.76 ± 2.2 falls in one-year to 0.76 plusmn; 1.4 falls (p <0.0001) over the 6-month intervention. No changes in functional outcome measures were observed. Vitamin D supplementation at the currently recommended dose of 800 IU/day increased blood vitamin D levels and reduced frequency of falls in older adults with low vitamin D levels and a recent fall history.

The aim of this study was to examine the associations between age, chronic pain, cognitive function, and pain sensitivity by comparing older and younger adults. The study included 30 older adults with chronic pain, 31 older adults without pain, 26 young adults with chronic pain, and 31 young adults without pain. Cognitive functions were assessed using the Mini-Mental State Examination, Stroop Test, and Clock Drawing Test. Pressure pain thresholds (PPT) were measured in the trapezius, deltoid, and tibialis anterior regions using an algometer. Significant differences were observed in most cognitive functions and PPTs between the groups, particularly between older adults with and without chronic pain, and young adults with and without chronic pain. Generally, moderate to strong negative correlations were found between pain sensitivity and cognitive performance in older adults with chronic pain. In contrast, young adults with chronic pain showed weaker and fewer correlations between pain sensitivity and cognitive function. Chronic pain has a more significant negative impact on cognitive function in older adults, who also exhibit stronger associations between pain sensitivity and cognitive decline. In contrast, younger adults with chronic pain demonstrate weaker correlations, potentially due to adaptive coping mechanisms. These findings highlight the need for age-specific interventions targeting both pain and cognitive decline in older populations.

Is there sufficient evidence to supplement omega-3 fatty acids to increase muscle mass and strength in young and older adults?

The mechanisms underlying the relationship between obesity and cognitive function remain unclear, particularly among older adults, where reliable evidence is limited. This study aimed to explore whether the relationship between obesity and cognitive function is mediated by sleep quality and blood pressure (BP) in older Chinese adults. We conducted an observational study using data from a cluster randomized controlled trial (RCT) with 5 follow-up periods involving older adults in rural China. The trial took place in Sichuan, China, from May 2021 to May 2023. Telephone Interview for Cognitive Status (TICS- 10) was used to assess the participants' cognitive function. Additionally, linear mixed-effects models and mediation analyses were performed. The mean age of participants was 70.89, and 225 out of 506 participants were males. Weight, waist circumference (WC), and hip circumference (HC) were positively associated with cognitive function, while compared to normal/underweight participants, participants with overweight had a significant association with cognitive function. Sleep quality mediated the association between weight and cognitive function (β = 0.01, (95% CI: 0.00 to 0.01), P < 0.001), accounting for a mediating effect proportion of 4.04% (95% CI: 2.19% to 8.00%). Diastolic blood pressure (DBP) mediated the association between overweight (β = 0.02, (95% CI: 0.00 to 0.05), P < 0.001), HC (β = 0.01, (95% CI: 0.00 to 0.01), P = 0.02), and WC (β = 0.01, (95% CI: 0.00, 0.01), P <0.001) and cognitive function, explaining approximately 4.46% (95% CI: 0.41% to 12.00%), 7.16% (95% CI: 0.36%, 17.00%), and 9.60% (95% CI: 1.11%, 25.00%) mediating proportion of the total effect, respectively. Our study highlights the potential mediating roles of sleep quality and DBP in the relationship between obesity and cognitive function. The findings contribute to understanding the obesity-cognition link in older adults, particularly in rural settings. However, limitations, such as self-reported sleep measures and unmeasured confounders, warrant caution. Further research is needed to clarify the underlying mechanisms and inform targeted interventions. Our study demonstrates a significant positive association between weight, body mass index (BMI), HC, and WC and cognitive function in older adults. These findings suggest that maintaining a moderately high level of overweight may be protective against cognitive decline in this population. Additionally, the study also provides insights into optimizing cognitive function through factors, such as sleep and BP management.

Despite well-documented declines in most cognitive domains, some emotional processes appear to be preserved or even enhanced in late adulthood. A good example of this is the information processing bias older adults show towards positive relative to negative emotional stimuli, often referred to as the age-related positivity effect. The present thesis presents a series of experiments that were designed to better understand the mechanisms that contribute to age-related changes in emotional processing, focusing in particular on the role of cognitive mechanisms and neural networks. In Study 1 aimed to identify the underlying cognitive mechanisms of the positivity effect. The primary focus of this study was to explore the role of distractors during the early attention allocation stage, and to also measure how selective attentional processes during encoding influence later memory outcomes for emotional items. The results showed that consistent with prior literature, a memory positivity effect was found among older relative to younger adults. However, of particular interest was the finding that, participants’ memory for negative targets was not influenced by the presence of positive distractors. This finding suggests that positive distractors did not automatically capture older adults’ attention during encoding for negative items. Importantly, we found that participants’ pupillary responses to negative items mediated the relationship between age and the memory positivity effect, indicating that older adults use their cognitive control resources when encoding negative information, perhaps to down regulate the impact of negative emotions on their memory. Collectively, these two findings provide converging support for the cognitive control account of the positivity effect. Study 2 used a similar paradigm to Study 1 to examine the underlying neural networks involved in processing emotional items during working memory encoding among older and younger adults. Results indicated that a cognitive control network that included fronto-parietal regions, was functionally connected to the left ventrolateral prefrontal cortex during the encoding of negative items among older adults. This network contributed to performance, both accuracy and response times, in older adults’ group. A less distributed network was found for encoding of positive items among older and both items among younger adults. Although older adults recruited a same network that was functionally connected to the amygdala for encoding positive and negative items, younger adults recruited this particular network specifically for encoding negative items. This network facilitated older adults’ higher accuracy and faster response times during retrieval. Taken together, the results from these functional connectivity analyses suggest that there is differential engagement of brain networks connected to these two regions, which are modulated by the emotional valence. While two separate brain networks underlying the encoding of emotionally valence targets are connected to the vlPFC region, one distinct network is functionally connected to the amygdala and subserves the processing of both positive and negative targets. In Study 3 age-related differences in neural substrates involved when processing happy and angry expressions presented with direct versus averted gaze were investigated. This research was motivated by studies that show older adults not only have difficulties processing emotional cues such as facial expression and eye gaze cues, but also have problems integrating these cues. Study 3 provides the first empirical examination of the underlying neural correlates of age-related difficulties in integrating communicative cues. The results showed that for angry facial expressions, younger adults recruited distinct networks while processing direct versus averted eye-gaze cues, however, older adults showed a lack of neural sensitivity to these cues, recruiting a single network for both types of stimuli. In contrast, for happy facial expressions, only older adults showed neural sensitivity to eye gaze cues. Participants’ performance on the scanner task was then correlated with a measure of theory of mind (TOM). Younger (but not older) adults’ performance on a measure of TOM and recognition of angry expressions was differentially correlated with activation in two sets of brain regions as a function of eye gaze. Unlike younger adults, older adults’ performance on TOM was also differentially correlated with the key node of mentalizing brain network during happy expressions as a function of eye gaze. The findings from Study 3 suggest that the age-related difficulties in integrating facial cues could be associated with the recruitment of the mentalizing network when the task imposes high demand on social-cognitive processing. Taken together, the three Studies reported in this thesis provide novel insights into our understanding of age-related differences in the processing of emotionally valenced items, particularly with respect to initial encoding of this information, and how this relates to later memory outcomes. Moreover, for the first time the neural correlates of integrating two important types of facial cue has been identified, and potentially linked to broader social cognitive difficulties. Overall, the findings of this thesis have broad implications for understanding the underlying cognitive mechanisms and neural networks that contribute to age-related differences in the processing of emotional stimuli.