Dose Response of Transcranial Photobiomodulation on Cognitive Efficiency in Healthy Older Adults: A Task-Related Functional Near-Infrared Spectroscopy Study.

Background: Alzheimer's disease has become increasingly prevalent among the older population, leading to significant social and economic burdens. Transcranial photobiomodulation (tPBM) has shown promise as a cognitive intervention for enhancing cognitive efficiency in healthy older adults, and individuals with mild cognitive impairment and Alzheimer's disease. However, determining the optimal tPBM dosage is crucial for ensuring effective and efficient intervention. Objective: This study aimed to compare the effects of different dosages in a single tPBM session on cognitive efficiency in healthy older adults. Methods: In this randomized controlled trial, 88 healthy older participants were assigned to either a single dose (irradiance = 30 mW/cm2, fluence = 10.8 J/cm2; n = 44) or a double dose (irradiance = 30 mW/cm2, fluence = 21.6 J/cm2; n = 44) tPBM session. Cognitive efficiency was assessed using functional near-infrared spectroscopy during a visual working memory span task. Results: The single dose group exhibited significantly greater cognitive efficiency enhancement, indicated by a more pronounced reduction in oxygenated hemoglobin during a challenging task level (span level 9) (p = 0.021, d = 0.50), and better working memory task performance (p = 0.045, d = 0.31). Furthermore, participants with better visuospatial abilities demonstrated greater improvement after a single dose (r = -0.42, p = 0.004). In contrast, participants with varying cognitive function did not exhibit additional benefits from a double dose (r = -0.22-0.15, p = 0.16-0.95). Conclusions: These findings suggest that higher tPBM dosages may not necessarily result in superior cognitive improvement in older adults.

Differences in the Efficiency of Cognitive Control across Young Adulthood: An ERP Perspective.

Young adulthood is a period of major life changes when everyday life becomes much more complex compared to adolescence. Such changes require highly efficient cognitive control. Developmental studies show that structural changes in the brain areas that support complex behavior continue into the early 20s. However, despite the fact that at the beginning of young adulthood, important behavioral and brain restructuring still occurs, most studies use broad age ranges for young adults (from 18 to 40 years of age) as a reference point for "adult" behavior. The aim of this study was to investigate age-related differences in the efficiency of cognitive control across young adulthood. In total, 107 individuals participated in this study and were divided into three age groups: 19-21, 23-26, and 28-44. We used a visual word categorization task to assess cognitive efficiency and event-related potentials (ERPs) to track events that take place from the stimulus onset until the actual behavioral response. We found age differences in both performance and amplitudes of the ERP components during the early stages of processing - P2 and N2. Our findings provide important evidence for the continuation of age-related changes in brain dynamics that underlie the efficiency of cognitive control even in the early 20s.

Photobiomodulation may enhance cognitive efficiency in older adults: a functional near-infrared spectroscopy study.

Introduction: The relative oxygenated hemoglobin (HbO) measured using functional near-infrared spectroscopy (fNIRS) has been considered as an index for cognitive loading, with the more difficult the task, the higher the level. A previous study reported that young adults who received transcranial photobiomodulation (tPBM) showed a reduced HbO of a difficult task, suggesting that tPBM may enhance cognitive efficiency. The present study further investigated the effect of tPBM on cognitive efficiency in older adults. Methods: Thirty participants received a single tPBM on the forehead for 350 s. Before and after tPBM, their HbO in the visual span task with various difficulties was measured with fNIRS. Results: After tPBM, participants exhibited significantly lower HbO in a harder (span 7) but not an easier level (span 2) of the task, but their behavioral performance remained unchanged. In addition, factors affecting the reduction of HbO were examined, and the results showed that individuals with better memory (as measured by a 30-min delayed recall test) showed more reduction of HbO. Discussion: The results suggest that tPBM may enhance cognitive efficiency, with individuals with better memory tend to benefit more.

Diagnosis concealment is prevalent in MS, and associated with diagnosis experience.

BACKGROUND: Receiving a diagnosis of multiple sclerosis (MS) can be stressful; later, patients may conceal their diagnosis. Here, we aimed to (1) assess prevalence of disclosure and concealment behaviors, and (2) explore whether diagnosis experience is associated with later concealment and if MS provider engagement on this topic modifies concealment. METHODS: In a survey-based study, MS patients completed DISCO-MS assessing disclosure and concealment and responded to questions about diagnosis experience and practitioner attention to disclosure. Frequency analysis and Pearson's correlations were used in exploratory analyses. RESULTS: 428 adults with MS participated. 49% (N = 201) conceal their diagnosis. Higher education [t(405) = 3.66, p < 0.001], younger age (r = -0.15, p = 0.002), and shorter disease duration (r = -0.18, p = 0.010) were associated with higher concealment. 39% (N = 159) anticipate negative consequences of disclosure. Individuals reporting positive diagnosis experience (26%, N = 102) were less likely to conceal later in disease course compared to those with negative experience (34%, N = 136) [t(233) = 2.483, p = 0.014]. Patients whose MS providers discussed disclosure (23%, N = 73) anticipated less negative consequences of disclosure [t(323) = 2.475, p = 0.014]. CONCLUSIONS: Diagnosis concealment is common in MS. Favorable diagnosis experience and provider attention to the topic of disclosure throughout the MS disease course may influence diagnosis concealment.

Perception of stress and cognitive efficiency in older adults with mild and moderate dementia during the COVID-19-related lockdown.

AIM: Many studies have been carried out with the aim of understanding the manifold effects of the novel coronavirus (Covid-19) on individuals' clinical and psychological states. This paper deals with perceived stress (PS) and cognitive efficiency (CE) in older adults with dementia during the first wave of the pandemic. The study also investigated the potential effects of PS and CE on participants' cognitive functioning. The modulating effect of cognitive reserve (CR) on these variables was also considered, given its well-known role in the onset and evolution of neurodegenerative diseases. METHOD: Thirty-eight older adults with mild/moderate dementia (mean age: 81.47 ± 5.05; mean MMSE pre-lockdown: 24.03 ± 3.14) were recruited for this study from March to May [4]. Two questionnaires, the Perceived Stress Scale (PSS) and the FLEI Mental Ability Questionnaire (FLEI), were administered to all participants by telephone every two weeks during lockdown (T1: early April, T2: mid-April, T3: early May). After lockdown, their neuropsychological and psychological profiles were assessed. Linear mixed-effects models were used to investigate changes over time. RESULTS: The level of PS increased at both Time 2 and Time 3 (f2 = 0.10). Cognitive functioning worsened during lockdown, resulting in lower scores at the post-lockdown evaluation (f2s = 0.09 and 0.06 for MMSE and ENB-2, respectively). The decrease in these scores was not associated with either PS or CE. Although the size of these effects was rather small, their clinical relevance is not negligible. CONCLUSION: Individuals with dementia seem to have experienced stress (S) during the first-wave of lockdown related to Covid-19. Cognition worsened during the pandemic, in accordance with the neurodegenerative nature of the disease, but it was unrelated to PS and CE.

Psychological power alters cognitive efficiency.

Power is known to promote cognitive processing in a goal-directed way. However, it is unknown whether powerful individuals invest more resources when pursuing their goals or whether they invest their resources more efficiently. We examined how experiencing high versus low power affects the efficient investment of cognitive resources using electroencephalography (EEG). Specifically, event-related desynchronization (ERD) in the upper alpha band (10.5-12.75 Hz) was used to quantify the use of cognitive resources during task completion. Results showed that high-power participants used fewer neural resources compared to low-power participants across the whole brain but task performance did not differ between groups. These findings demonstrate that, instead of investing more resources, high-power participants performed the task with greater cognitive efficiency compared to low-power participants. Performing tasks efficiently could help powerholders deal with their demanding jobs and responsibilities.

Targeting HIV-Related Neurocognitive Impairments with Cognitive Training Strategies: Insights from the Cognitive Aging Literature.

Approximately 50% of older adults with HIV meet the Frascati diagnostic criteria of HIV-associated neurocognitive disorders (HAND) which can interfere with everyday function such as medication adherence, employment, and driving ability, thus reducing quality of life. As the number of older adults with HIV continues to grow, many will become vulnerable to cognitive frailty, especially as they experience multimorbidities, polypharmacy, and geriatric syndromes. Healthcare professionals need strategies to prevent, remediate, and compensate for cognitive losses observed in memory, language, executive functioning, and speed of processing. Sadly, there are no standard protocols or accepted treatment/intervention guidelines to address HAND at this time. Fortunately, evidence from the cognitive aging literature indicates that cognitive training can protect and improve cognition in normal older adults and may even reduce the incidence of dementia/MCI. This article provides the scientific context in which computerized cognitive training approaches have been successfully used in older adults and provides examples of how these approaches have been translated to adults with HIV. Evidence from ongoing clinical trials are also presented that suggest that reversing a diagnosis of HAND may be possible. Recommendations for clinical practice and research are provided.

High cognitive load during attention to images of models reduces young women's social comparisons: Further evidence against cognitive efficiency.

Mental processes that are conducted frequently can become highly cognitively efficient, meaning they can be carried out while we are doing other tasks (i.e., under high cognitive load). Given that young women report frequently comparing their appearance to models in media images, we examined whether such social comparisons are cognitively efficient. Our sample (N = 227) consisted of young women who felt above-average pressure from the media regarding appearance. Cognitive load was manipulated by memorizing either a simple (low load) or complex (high load) sequence of colours from attractive-model or control images. Participants who viewed models under low load compared themselves with the models, and significantly decreased in appearance satisfaction (but experienced no statistically significant change in negative affect). Participants under high load made fewer comparisons and their appearance satisfaction did not significantly decrease. These results suggest that social comparisons are not highly cognitively efficient and instead require cognitive effort.

Algorithms in the historical emergence of word senses.

Human language relies on a finite lexicon to express a potentially infinite set of ideas. A key result of this tension is that words acquire novel senses over time. However, the cognitive processes that underlie the historical emergence of new word senses are poorly understood. Here, we present a computational framework that formalizes competing views of how new senses of a word might emerge by attaching to existing senses of the word. We test the ability of the models to predict the temporal order in which the senses of individual words have emerged, using an historical lexicon of English spanning the past millennium. Our findings suggest that word senses emerge in predictable ways, following an historical path that reflects cognitive efficiency, predominantly through a process of nearest-neighbor chaining. Our work contributes a formal account of the generative processes that underlie lexical evolution.

Different levels of visual perceptual skills are associated with specific modifications in functional connectivity and global efficiency.

The disembedding ability (i.e., the ability to identify a simple masked figure within a complex one) depends on attentional mechanisms, executive functions and working memory. Recent cognitive models ascribed different levels of disembedding task performance to the efficiency of the subtended mental processes engaged during visuo-spatial perception. Here we aimed at assessing whether different levels of the disembedding ability were associated to the functional signatures of neural efficiency, defined as a specific modulation in response magnitude and functional connectivity strength in task-related areas. Consequently, brain activity evoked by a visual task involving the disembedding ability was acquired using functional magnetic resonance imaging (fMRI) in a sample of 23 right-handed healthy individuals. Brain activity was analyzed at different levels of information processing, from local responses to connectivity interactions between brain nodes, as far as to network topological properties. All different levels of information processing were significantly modulated by individual behavioral performance. Specifically, single voxel response magnitude, connectivity strength of the right intrahemispheric and interhemispheric edges, and graph measures (i.e., local and global efficiency) were negatively associated to behavioral performance. Altogether, these results indicate that efficiency during a disembedding task cannot be merely attributed to a reduced neural recruitment of task-specific regions, but can be better characterized as an enhanced functional hemispherical asymmetry.

Cognitive Slowing in Gulf War Illness Predicts Executive Network Hyperconnectivity: Study in a Population-Representative Sample.

Cognitive slowing is a prevalent symptom observed in Gulf War Illness (GWI). The present study assessed the extent to which functional connectivity between dorsolateral prefrontal cortex (DLPFC) and other task-relevant brain regions was predictive of GWI-related cognitive slowing. GWI patients (n = 54) and healthy veteran controls (n = 29) were assessed on performance of a processing speed task (the Digit Symbol Substitution Task; DSST) while undergoing functional magnetic resonance imaging (fMRI). GWI patients were slower on the DSST relative to controls. Bilateral DLPFC connectivity with task-relevant nodes was altered in GWI patients compared to healthy controls during DSST performance. Moreover, hyperconnectivity in these networks predicted GWI-related increases in reaction time on the DSST, whereas hypoconnectivity did not. These results suggest that GWI-related cognitive slowing reflects reduced efficiency in cortical networks.

Allocentric but not egocentric visual memory difficulties in adults with ADHD may represent cognitive inefficiency.

Attention Deficit Hyperactivity Disorder (ADHD) has often been conceptualized as arising executive dysfunctions (e.g., inattention, defective inhibition). However, recent studies suggested that cognitive inefficiency may underlie many ADHD symptoms, according to reaction time and processing speed abnormalities. This study explored whether a non-timed measure of cognitive inefficiency would also be abnormal. A sample of 23 ADHD subjects was compared to 23 controls on a test that included both egocentric and allocentric visual memory subtests. A factor analysis was used to determine which cognitive variables contributed to allocentric visual memory. The ADHD sample performed significantly lower on the allocentric but not egocentric conditions. Allocentric visual memory was not associated with timed, working memory, visual perception, or mental rotation variables. This paper concluded by discussing how these results supported a cognitive inefficiency explanation for some ADHD symptoms, and discussed future research directions.

Predictive value of different conventional and non-conventional MRI-parameters for specific domains of cognitive function in multiple sclerosis.

OBJECTIVE: While many studies correlated cognitive function with changes in brain morphology in multiple sclerosis (MS), few of them used a multi-parametric approach in a single dataset so far. We thus here assessed the predictive value of different conventional and quantitative MRI-parameters both for overall and domain-specific cognitive performance in MS patients from a single center. METHODS: 69 patients (17 clinically isolated syndrome, 47 relapsing-remitting MS, 5 secondary-progressive MS) underwent the "Brief Repeatable Battery of Neuropsychological Tests" assessing overall cognition, cognitive efficiency and memory function as well as MRI at 3 Tesla to obtain T2-lesion load (T2-LL), normalized brain volume (global brain volume loss), normalized cortical volume (NCV), normalized thalamic volume (NTV), normalized hippocampal volume (NHV), normalized caudate nuclei volume (NCNV), basal ganglia R2* values (iron deposition) and magnetization transfer ratios (MTRs) for cortex and normal appearing brain tissue (NABT). RESULTS: Regression models including clinical, demographic variables and MRI-parameters explained 22-27% of variance of overall cognition, 17-26% of cognitive efficiency and 22-23% of memory. NCV, T2-LL and MTR of NABT were the strongest predictors of overall cognitive function. Cognitive efficiency was best predicted by NCV, T2-LL and iron deposition in the basal ganglia. NTV was the strongest predictor for memory function and NHV was particularly related to memory function. CONCLUSIONS: The predictive value of distinct MRI-parameters differs for specific domains of cognitive function, with a greater impact of cortical volume, focal and diffuse white matter abnormalities on overall cognitive function, an additional role of basal ganglia iron deposition on cognitive efficiency, and thalamic and hippocampal volume on memory function. This suggests the usefulness of using multiparametric MRI to assess (micro)structural correlates of different cognitive constructs.

Investigating the neural bases for intra-subject cognitive efficiency changes using functional magnetic resonance imaging.

Several fMRI studies have examined brain regions mediating inter-subject variability in cognitive efficiency, but none have examined regions mediating intra-subject variability in efficiency. Thus, the present study was designed to identify brain regions involved in intra-subject variability in cognitive efficiency via participant-level correlations between trial-level reaction time (RT) and trial-level fMRI BOLD percent signal change on a processing speed task. On each trial, participants indicated whether a digit-symbol probe-pair was present or absent in an array of nine digit-symbol probe-pairs while fMRI data were collected. Deconvolution analyses, using RT time-series models (derived from the proportional scaling of an event-related hemodynamic response function model by trial-level RT), were used to evaluate relationships between trial-level RTs and BOLD percent signal change. Although task-related patterns of activation and deactivation were observed in regions including bilateral occipital, bilateral parietal, portions of the medial wall such as the precuneus, default mode network regions including anterior cingulate, posterior cingulate, bilateral temporal, right cerebellum, and right cuneus, RT-BOLD correlations were observed in a more circumscribed set of regions. Positive RT-BOLD correlations, where fast RTs were associated with lower BOLD percent signal change, were observed in regions including bilateral occipital, bilateral parietal, and the precuneus. RT-BOLD correlations were not observed in the default mode network indicating a smaller set of regions associated with intra-subject variability in cognitive efficiency. The results are discussed in terms of a distributed area of regions that mediate variability in the cognitive efficiency that might underlie processing speed differences between individuals.

[A motivational approach of cognitive efficiency in nursing home residents]. / Approche motivationnelle de l'efficience cognitive de personnes âgées vivant en institution.

Despite a widespread concern with self-determined motivation (behavior is engaged in "out of pleasure" or "out of choice and valued as being important") and psychological adjustment in later life (well-being, satisfaction in life, meaning of life, or self-esteem), very little is known about the existence and nature of the links between self-determined motivation and cognitive efficiency. The aim of the present study was to investigate theses links in nursing home residents in the framework of the Self-determination theory (SDT) (Deci & Ryan, 2002), in which motivational profile of a person is determined by the combination of different kinds of motivation. We hypothesized that self-determined motivation would lead to higher cognitive efficiency. Participants. 39 (32 women and 7 men) elderly nursing home residents (m= 83.6 ± 9.3 year old) without any neurological or psychiatric disorders (DSM IV) or depression or anxiety (Hamilton depression rating scales) were included in the study. Methods. Cognitive efficiency was evaluated by two brief neuropsychological tests, the Mini mental state examination (MMSE) and the Frontal assessment battery (FAB). The motivational profile was assessed by the Elderly motivation scale (Vallerand & 0'Connor, 1991) which includes four subscales assessing self- and non-self determined motivation to engage oneself in different domains of daily life activity. Results. The neuropsychological scores were positively and significantly correlated to self-determined extrinsic motivation (behavior is engaged in "out of choice" and valued as being important), and the global self-determination index (self-determined motivational profile) was the best predictor of the cognitive efficiency. Conclusion. The results support the SDT interest for a qualitative assessment of the motivation of the elderly people and suggest that a motivational approach of cognitive efficiency could help to interpret cognitive performances exhibited during neuropsychological assessment.

Distinct neural markers of TVA-based visual processing speed and short-term storage capacity parameters.

An individual's visual attentional capacity is characterized by 2 central processing resources, visual perceptual processing speed and visual short-term memory (vSTM) storage capacity. Based on Bundesen's theory of visual attention (TVA), independent estimates of these parameters can be obtained from mathematical modeling of performance in a whole report task. The framework's neural interpretation (NTVA) further suggests distinct brain mechanisms underlying these 2 functions. Using an interindividual difference approach, the present study was designed to establish the respective ERP correlates of both parameters. Participants with higher compared to participants with lower processing speed were found to show significantly reduced visual N1 responses, indicative of higher efficiency in early visual processing. By contrast, for participants with higher relative to lower vSTM storage capacity, contralateral delay activity over visual areas was enhanced while overall nonlateralized delay activity was reduced, indicating that holding (the maximum number of) items in vSTM relies on topographically specific sustained activation within the visual system. Taken together, our findings show that the 2 main aspects of visual attentional capacity are reflected in separable neurophysiological markers, validating a central assumption of NTVA.

N400 amplitude reduction correlates with an increase in pupil size.

Pupil dilation is classically associated with increase in cognitive load in humans. Here, we studied the potential link between human pupil dilation and meaning integration effort as indexed by event-related brain potentials (ERPs). We recorded pupil size variation and ERPs simultaneously while participants were presented with matching or unrelated picture-word pairs. Whilst relatedness in meaning between spoken words and pictures typically modulated ERPs, pupil size was also affected quickly after picture onset. Moreover, during the time-window associated with meaning integration, greater pupil dilation correlated with less negative N400 amplitudes elicited by unrelated pictures. Since pupil dilation has been linked to activity of the locus coeruleus-norepinephrine (LC-NE) system, these findings may provide new insights into the suggested link between human high-level cognitive function and activity of the LC-NE system.