Eye-tracking training improves visuospatial working memory of children with attention-deficit/hyperactivity disorder and autism spectrum disorder.

Given the close connection between eye movement and frontal lobe functions and some evidence supporting the effect of eye-tracking training on enhancing cognitive performance mediated by the frontal lobe, this study aimed to explore if after-school eye-tracking training can improve the visuospatial working memory (VSWM) and cognitive flexibility performance in children with attention-deficit/hyperactivity disorder (ADHD) and autism spectrum disorder (ASD). This study is a non-randomized cluster trial. Forty children from eight primary schools were selected, half receiving eye-tracking training for 20 sessions over 9 months, while the other half served as a waitlist control. They were matched on demographic characteristics and baseline cognitive performance. Their VSWM and cognitive flexibility were assessed at the beginning and end of the study. Results showed that children who received eye-tracking training, but not those on a waitlist, exhibited significant improvements in the total score and working memory span of the VSWM tests, and the correct responses in cognitive flexibility tests. Specifically, VSWM performance at higher span levels (5 or above) yielded a greater improvement. The findings suggest that eye-tracking training can be a feasible and effective after-school program for improving working memory and cognitive flexibility performance in children with ADHD and ASD. This study was prospectively registered at ClinicalTrials.gov (https://clinicaltrials.gov/, trial number: NCT05428657).

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.

fNIRS as a biomarker for individuals with subjective memory complaints and MCI.

INTRODUCTION: Identifying individuals at risk of developing dementia is crucial for early intervention. Mild cognitive impairment (MCI) and subjective memory complaints (SMCs) are considered its preceding stages. This study aimed to assess the utility of functional near-infrared spectroscopy (fNIRS) in identifying individuals with MCI and SMC. METHODS: One hundred fifty-one participants were categorized into normal cognition (NC); amnestic MCI (aMCI); non-amnestic MCI (naMCI); and mild, moderate, and severe SMC groups. Task-related prefrontal hemodynamics were measured using fNIRS during a visual memory span task. RESULTS: Results showed significantly lower oxyhemoglobin (HbO) levels in aMCI, but not in naMCI, compared to the NC. In addition, severe SMC had lower HbO levels than the NC, mild, and moderate SMC. Receiver operating characteristic analysis demonstrated 69.23% and 69.70% accuracy in differentiating aMCI and severe SMC from NC, respectively. DISCUSSION: FNIRS may serve as a potential non-invasive biomarker for early detection of dementia. HIGHLIGHTS: Only amnestic mild cognitive impairment (aMCI), but not non-amnestic MCI, showed lower oxyhemoglobin (HbO) than normal individuals. Reduced HbO was observed in those with severe subjective memory complaints (SMCs) compared to normal cognition (NC), mild, and moderate SMCs. Functional near-infrared spectroscopy measures were associated with performance in memory assessments. Prefrontal hemodynamics could distinguish aMCI and severe SMC from NC.

Chanwuyi Lifestyle Medicine Program Improves Memory and Executive Functions of Older Adults With Mild Cognitive Impairment.

The Chanwuyi Lifestyle Medicine Program (CLMP) was found to enhance the memory and executive functions of older adults with or without subjective memory complaints. The present study investigated whether similar beneficial effects can be extended to mild cognitive impairment (MCI). Twenty-four older adults with MCI were randomly assigned to receive the CLMP (the experimental group) or strategic memory training (SMT; the active control group) for 10 weeks. They were assessed by neuropsychological tests at baseline and post-intervention. Older adults showed similar visual and verbal memory improvements after receiving the CLMP and SMT. Yet, only those who received the CLMP showed distinct improvements in planning/organization, working memory, and attention in terms of accuracy, with greater cognitive gains associated with older age and lower levels of education and baseline cognitive functions. This study provides preliminary evidence for the effects of the CLMP on improving memory, attention, and executive functions in MCI.

Temporal processing tele-intervention improves language, attention, and memory in children with neurodevelopmental disorders.

Objective: Temporal processing is the brain's ability to process rapid successive stimuli, and children with neurodevelopmental disorders showed temporal processing deficits. Empirical evidence suggests that in-person intervention on temporal processing improves various cognitive functions of these children, and the present study aimed to study the effects of temporal processing tele-intervention (TPT) on the cognitive functions of children with neurodevelopmental disorders. Methods: Ninety-five children with neurodevelopmental disorders were recruited and randomly assigned to remotely receive either TPT or conventional language remediation (CLR) in 20 parallel group-based intervention sessions once per week. Their cognitive functions were assessed before and after the intervention. Results: The TPT group demonstrated a specific and significant improvement in working memory (p < .001). While there was an overall significant improvement in sustained attention in terms of processing speed after both types of intervention (p = .006), the positive effects of TPT might be more prominent than that of CLR given the significant pre-post difference after receiving TPT (p = .012) but not CLR (p = .21). Regarding rapid naming accuracy which had marginally significant improvement after the intervention (p = .03), the trend of improvement in TPT (p = .05) also seemed more apparent than that of CLR (p = .18). Finally, the TPT group had significant improvement in word knowledge (p < .001), rapid naming speed (p < .001), sustained attention in terms of accuracy (p < .001), and verbal learning and memory (p < .01) to an extent similar to that of the CLR group. Conclusions: These findings suggest that TPT can be a potential intervention for improving cognitive functions in children with neurodevelopmental disorders. Clinical trial registration number: NCT05428657 at ClinicalTrials.gov (https://clinicaltrials.gov/).

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.

Prefrontal hemodynamic features of older adults with preserved visuospatial working memory function.

Memory decline has been observed in the aging population and is a risk factor for the later development of dementia. Understanding how memory is preserved in older adults has been an important topic. The present study examines the hemodynamic features of older adults whose memory is comparable with that of young adults. In the present study, 45 younger and 45 older adults performed the visual memory task with various difficulty levels (i.e., the items to be remembered), and their cerebral hemodynamics at each level were measured by functional near-infrared spectroscopy (fNIRS). The results showed that older adults exhibited higher activation than younger adults under more difficult but not easier levels. In addition, older adults whose performance is comparable with that of young adults (i.e., being able to remember six items) showed more right-lateralized activation. However, those unable to do so showed more left-lateralized activation. The results suggested that high-performing older adults possess successful compensatory mechanisms by recruiting cognitive resources in a specialized brain region.

Effects of prefrontal transcranial direct current stimulation on social functioning in autism spectrum disorder: A randomized clinical trial.

LAY ABSTRACT: Currently available pharmacological and behavioral interventions for adolescents and young adults with autism spectrum disorder (ASD) yield only modest effect in alleviating their core behavioral and cognitive symptoms, and some of these treatment options are associated with undesirable side effects. Hence, developing effective treatment protocols is urgently needed. Given emerging evidence shows that the abnormal connections of the frontal brain regions contribute to the manifestations of ASD behavioral and cognitive impairments, noninvasive treatment modalities that are capable in modulating brain connections, such as transcranial direct current stimulation (tDCS), have been postulated to be potentially promising for alleviating core symptoms in ASD. However, whether tDCS can reduce behavioral symptoms and enhance cognitive performance in ASD remains unclear. This randomized controlled trial involving 105 adolescents and young adults with ASD showed that multiple sessions of a tDCS protocol, which was paired up with computerized cognitive training, was effective in improving social functioning in adolescents and young adults with ASD. No prolonged and serious side effects were observed. With more future studies conducted in different clinical settings that recruit participants from a wider age range, this tDCS protocol may be potentially beneficial to a broad spectrum of individuals with autism.

Temporal processing deficit in children and adolescents with autism spectrum disorder: An online assessment.

Objective: The sensory deficit has been considered as one of the core features in children and adolescents with autism spectrum disorder (ASD). The present study aimed to examine the temporal processing of simple and more complex auditory inputs in ASD children and adolescents with an online assessment that can be conducted remotely. Methods: One hundred fifty-eight children and adolescents aged 5-17 years participated in this study, including 79 ASD participants and 79 typically developing (TD) participants. The online assessment consisted of two temporal-order judgment tasks that required repeating the sequence of two pure tones or consonant-vowel (CV) syllabic pairs at varying interstimulus intervals (ISIs). Results: Significantly lower accuracy rates were found in ASD than TD participants in the pure tone and the CV conditions with both short and long ISI. In addition, ASD participants (M = 245.97 ms) showed a significantly higher passing threshold than TD participants (M = 178.84 ms) in the CV task. Receiver operating characteristic analysis found that the age × ISI passing threshold composite yielded a sensitivity of 74.7% and a specificity of 50.6% at the cutoff point of -0.307 in differentiating ASD participants from TD participants. Conclusion: In sum, children and adolescents with ASD showed impaired temporal processing of both simple and more complex auditory stimuli, and the online assessment seems to be sensitive in differentiating individuals with ASD from those with TD.

Effectiveness of lifestyle medicine on cognitive functions in mild cognitive impairments and dementia: A systematic review on randomized controlled trials.

Mild cognitive impairment (MCI) and dementia are associated with lifestyle risk factors, making lifestyle medicine a potentially viable intervention for people with MCI and dementia. The present study aims to examine the effectiveness of lifestyle medicine on cognitive functions among people with MCI and dementia, by performing a systematic review and meta-analysis on randomized controlled trials (RCT). A systematic literature search was conducted to extract RCTs adopting lifestyle interventions of diet, exercise, and stress management or emotional well-being. Results showed that 65 studies were eligible. Exercise was the most promising lifestyle intervention that improved various cognitive functions among people with MCI and dementia, and was more effective in MCI than in dementia. Interventions on stress management or emotional well-being did not show a significant effect on people with MCI, and the evidence for people with dementia was insufficient to conclude. Similarly, due to the lack of RCTs on a healthy dietary pattern, the effectiveness of diet interventions was not examined. In conclusion, the exercise component of lifestyle medicine can be an effective and clinically significant intervention for protecting people with MCI and dementia against cognitive declines, especially when served as an early intervention at the stage of MCI.

Can transcranial photobiomodulation improve cognitive function? A systematic review of human studies.

BACKGROUND: Transcranial photobiomodulation (tPBM) has been studied for over a decade as a possible cognitive intervention. OBJECTIVE: To evaluate the effect of tPBM for enhancing human cognitive function in healthy adults and remediating impaired cognitive function in adults with cognitive disorders. METHODS: A systematic literature search from three electronic databases (PubMed, Scopus, Web of Science) was conducted from 1987 to May 2022. The cognitive function being evaluated included learning and memory, attention, executive function, language, and global cognitive function. RESULTS: Of the 35 studies identified, 29 (82.9 %) studies reported positive improvement in cognitive functions after tPBM. All nine studies on participants with subjective memory complaints, mild cognitive impairment, and dementia, showed positive outcomes. Seven (87.5 %) studies on traumatic brain injury (TBI) patients also showed positive results. A series of clinical trials on stroke patients showed positive trends on improved neurological deficit at first, but was prematurely terminated later at phase III due to the lack of statistical significance. One of the most common protocols for clinical populations employed devices delivering near-infrared light (810 nm), the irradiance of 20-25 mW/cm2, and fluence of 1-10 J/cm2. While this was common, the reviewed protocols also included other wavelengths of light ranging from visible, red (630-635 nm) to invisible near-infrared maximum wavelengths of 1060-1068 nm. CONCLUSIONS: tPBM seems to improve cognitive function. However, only half of the reviewed clinical trials were randomized control trials, further investigation is warranted.

Temporal processing deficit in children with attention-deficit/hyperactivity disorder: An online assessment.

Objective: Temporal processing deficits were found among children with attention-deficit/hyperactivity disorder (ADHD). The present study aims to develop an online temporal processing assessment that can be conducted remotely, and the sensitivity of the test was assessed on a group of children with ADHD. Methods: A total of 188 children were recruited, including 94 typically developing (TD) children, and 94 children with ADHD. The online assessment consists of two temporal-order judgment (TOJ) tasks. One task used tone pairs presented with two interstimulus intervals (ISIs) (305ms and 40ms). Another task used pairs of consonant-vowel (CV) syllables with 20 varying ISI levels. Participants were asked to determine the sequence of the sound pairs. Results: The results showed that ADHD children were less accurate (ISI 305ms: M = 83.90%; ISI 40ms: M = 66.28%) than TD children (ISI 305ms: M = 89.36%; ISI 40ms: M = 77.16%) in the tone task. Similarly, ADHD children showed a higher ISI passing threshold (M = 283.64ms) than TD children (M = 199.76ms) and higher accuracy in the CV task. Hierarchical binary logistic regression suggested a model to predict ADHD children using accuracy in ISI 40ms in the tone task and ISI passing threshold in the CV task. Receiver operating characteristic (ROC) analysis yielded a sensitivity of 75.58% and a specificity of 51.11%. Conclusion: ADHD children showed temporal processing deficits of both tones and CVs. The online assessment may be a valid tool for differentiating ADHD children from TD children.

Eye-tracking training improves the learning and memory of children with learning difficulty.

Children who experience difficulty in learning at mainstream schools usually are provided with remediation classes after school to facilitate their learning. The present study aims to evaluate an innovative eye-tracking training as possible alternative remediation. Our previous findings showed that children who received eye-tracking training demonstrated improved attention and inhibitory control, and the present randomized controlled study aims to evaluate if eye-tracking training can also enhance the learning and memory of children. Fifty-three primary school students with learning difficulty (including autism spectrum disorder, attention-deficit/hyperactivity disorder, specific learning disorder, specific language impairment and borderline intellectual functioning) were recruited and randomly assigned to either the Eye-tracking Training group or the after-school remediation class. They were assessed on their learning and memory using the Hong Kong List Learning Test before and after 8-month training. Twenty weekly parallel sessions of training, 50 min per session, were provided to each group. Children who received the eye-tracking training, not those in the control group, showed a significant improvement in memory as measured by the delayed recall. In addition, the Eye-Tracking Training group showed significantly faster learning than the control group. Also, the two groups showed a significant improvement in their reading abilities. In sum, eye-tracking training may be effective training for enhancing the learning and memory of children with learning difficulties.

Digital Cognitive Biomarker for Mild Cognitive Impairments and Dementia: A Systematic Review.

The dementia population is increasing as the world's population is growing older. The current systematic review aims to identify digital cognitive biomarkers from computerized tests for detecting dementia and its risk state of mild cognitive impairment (MCI), and to evaluate the diagnostic performance of digital cognitive biomarkers. A literature search was performed in three databases, and supplemented by a Google search for names of previously identified computerized tests. Computerized tests were categorized into five types, including memory tests, test batteries, other single/multiple cognitive tests, handwriting/drawing tests, and daily living tasks and serious games. Results showed that 78 studies were eligible. Around 90% of the included studies were rated as high quality based on the Newcastle-Ottawa Scale (NOS). Most of the digital cognitive biomarkers achieved comparable or even better diagnostic performance than traditional paper-and-pencil tests. Moderate to large group differences were consistently observed in cognitive outcomes related to memory and executive functions, as well as some novel outcomes measured by handwriting/drawing tests, daily living tasks, and serious games. These outcomes have the potential to be sensitive digital cognitive biomarkers for MCI and dementia. Therefore, digital cognitive biomarkers can be a sensitive and promising clinical tool for detecting MCI and dementia.

Prefrontal Activation During Effortful Processing Differentiates Memory Abilities in Adults with Memory Complaints.

BACKGROUND: Identifying individuals at increased risks for developing Alzheimer's disease (AD) is crucial for early intervention. Memory complaints are associated with brain abnormalities characteristic of AD in cognitively normal older people. However, the utility of memory complaints for predicting mild cognitive impairment (MCI) or AD onset remains controversial, likely due to the heterogeneous nature of this construct. OBJECTIVE: We investigated whether prefrontal oxygenation changes measured by functional near-infrared spectroscopy (fNIRS) during an arduous cognitive task, previously shown to be associated with the AD syndrome, could differentiate memory abilities among individuals with memory complaints. Episodic memory performance was adopted as a proxy for MCI/AD risks since it has been shown to predict AD progression across stages. METHODS: Thirty-six adults self-reporting memory complaints in the absence of memory impairment completed a verbal list learning test and underwent a digit n-back paradigm with an easy (0-back) and a difficult (2-back) condition. K-means clustering was applied to empirically derive memory complaint subgroups based on fNIRS-based prefrontal oxygenation changes during the effortful 2-back task. RESULTS: Cluster analysis revealed two subgroups characterized by high (n = 12) and low (n = 24) bilateral prefrontal activation during the 2-back but not a 0-back task. The low activation group was significantly less accurate across the n-back task and recalled significantly fewer words on the verbal memory test compared to the high activation group. CONCLUSION: fNIRS may have the potential to differentiate verbal memory abilities in individuals with self-reported memory complaints.

Altered Cytokine and BDNF Levels in Individuals with Autism Spectrum Disorders.

Previous studies have shown that immunological factors are involved in the pathogenesis of autism spectrum disorders (ASDs). The present study examined whether immunological abnormalities are associated with cognitive and behavioral deficits in children with ASD and whether children with ASD show different immunological biomarkers and brain-derived neurotrophic factor BDNF levels than typically developing (TD) children. Sixteen children with TD and 18 children with ASD, aged 6-18 years, voluntarily participated in the study. Participants' executive functions were measured using neuropsychological tests, and behavioral measures were measured using parent ratings. Immunological measures were assessed by measuring the participants' blood serum levels of chemokine ligand 2 (CCL2) and chemokine ligand 5 (CCL5). Children with ASD showed greater deficits in cognitive functions as well as altered levels of immunological measures when compared to TD children, and their cognitive functions and behavioral deficits were significantly associated with increased CCL5 levels and decreased BDNF levels. These results provide evidence to support the notion that altered immune functions and neurotrophin deficiency are involved in the pathogenesis of ASD.

Neurophysiological and behavioral effects of multisession prefrontal tDCS and concurrent cognitive remediation training in patients with autism spectrum disorder (ASD): A double-blind, randomized controlled fNIRS study.

BACKGROUND: The clinical effects and neurophysiological mechanisms of prefrontal tDCS and concurrent cognitive remediation training in individuals with autism spectrum disorder (ASD) remain unclear. OBJECTIVE: This two-armed, double-blind, randomized, sham-controlled trial aimed to investigate the beneficial effects of tDCS combined with concurrent cognitive remediation training on adolescents and young adults with ASD. METHODS: Participants were randomly assigned to either active or sham tDCS groups and received 1.5 mA prefrontal tDCS with left dorsolateral prefrontal cortex (dlPFC) cathode placement and right supraorbital region anode placement for 20 minutes over two consecutive weeks. tDCS was delivered concurrently with a computerized cognitive remediation training program. Social functioning and its underlying cognitive processes, as well as prefrontal resting-state functional connectivity (rsFC), were measured. RESULTS: The results from 41 participants indicated that multisession prefrontal tDCS, compared to sham tDCS, significantly enhanced the social functioning of ASD individuals [F(1,39) = 4.75, p = .035, ηp2 = 0.11]. This improvement was associated with enhanced emotion recognition [F(1,39) = 8.34, p = .006, ηp2 = 0.18] and cognitive flexibility [F(1,39) = 4.91, p = .033, ηp2 = 0.11]. Specifically, this tDCS protocol optimized information processing efficiency [F(1,39) = 4.43, p = .042, ηp2 = 0.10], and the optimization showed a trend to be associated with enhanced rsFC in the right medial prefrontal cortex (ρ = 0.339, pFDR = .083). CONCLUSION: Multisession tDCS with left dlPFC cathode placement and right supraorbital region anode placement paired with concurrent cognitive remediation training promoted social functioning in individuals with ASD. This appeared to be associated with the enhancement of the functional connectivity of the right medial PFC, a major hub for flexible social information processing, allowing these individuals to process information more efficiently in response to different social situations. TRIAL REGISTRATION: ClinicalTrials.gov (ID: NCT03814083).

Effects of working memory load on frontal connectivity in children with autism spectrum disorder: a fNIRS study.

Individuals with autism spectrum disorder (ASD) perform poorly in working memory (WM) tasks, with some literature suggesting that their impaired performance is modulated by WM load. While some neuroimaging and neurophysiological studies have reported altered functional connectivity during WM processing in individuals with autism, it remains largely unclear whether such alterations are moderated by WM load. The present study aimed to examine the effect of WM load on functional connectivity within the prefrontal cortex (PFC) in ASD using functional near-infrared spectroscopy (fNIRS). Twenty-two children with high-functioning ASD aged 8-12 years and 24 age-, intelligent quotient (IQ)-, sex- and handedness-matched typically developing (TD) children performed a number n-back task with three WM loads (0-back, 1-back, and 2-back). Hemodynamic changes in the bilateral lateral and medial PFC during task performance were monitored using a multichannel NIRS device. Children with ASD demonstrated slower reaction times, specifically during the "low load" condition, than TD children. In addition, the ASD and TD groups exhibited differential load-dependent functional connectivity changes in the lateral and medial PFC of the right but not the left hemisphere. These findings indicate that WM impairment in high-functioning ASD is paralleled by load-dependent alterations in right, but not left, intrahemispheric connectivity during WM processing in children with ASD. A disruption of functional neural connections that support different cognitive processes may underlie poor performance in WM tasks in ASD.

Photobiomodulation improves frontal lobe cognitive functions and mental health of older adults with non-amnestic mild cognitive impairment: Case studies.

Introduction: This study investigated the effects of transcranial photobiomodulation (tPBM) on improving the frontal lobe cognitive functions and mental health of older adults. Methods: Three older adults with mild cognitive impairment (MCI) of the non-amnestic type received 18-session tPBM stimulation for 9 weeks and were assessed with neuropsychological tests of memory and executive functions and standardized questionnaires on depressive and anxiety symptoms, global cognitive functions, and daily functioning abilities before and after tPBM stimulation. Results: At baseline, their intrusion and/or perseveration errors in a verbal memory test and a fluency test, as measures of the frontal lobe cognitive functions, were in the borderline to severely impaired range at baseline. After tPBM stimulation, the three older adults showed various levels of improvement in their frontal lobe cognitive functions. One older adult's intrusion and perseveration errors improved from the <1st-2nd percentile (moderately to severely impaired range) to the 41st-69th percentile (average range), another older adult's intrusion errors improved from the 11th percentile to the 83rd percentile, and the third older adult's intrusion errors improved from the 5th percentile to the 56th percentile. Moreover, improvements in their anxiety and/or depressive symptoms were also observed. One older adult's depressive and anxiety symptoms improved from the severe range at baseline to the mild range after the intervention. The other two older adults' depressive symptoms improved from the mild range at baseline to the normal range after the intervention. Discussion: These findings provide preliminary support for the potential of tPBM to improve the frontal lobe cognitive functions and mental health of older adults with MCI. Given the small sample size of only three older adults and the absence of a placebo control group, larger randomized controlled studies are needed to confirm its potential.

Depressive and anxiety symptoms are related to decreased lateral prefrontal cortex functioning during cognitive control in older people.

Some studies have found a relationship between negative emotional symptoms and decreased lateral PFC functioning during a cognitive control task in healthy younger adults. Here, we asked whether this relationship is also present in the general older population and across different functional domains of the lateral PFC. Thirty-six older people (13 males) self-reported their recent depressive and anxiety symptoms. They also took two cognitive control tasks known to differentially engage the lateral frontoparietal network (digit n-back task) and the lateral frontotemporal network (Category Fluency Test) while hemodynamic changes in the PFC were monitored by functional near-infrared spectroscopy (fNIRS). Both depressive and anxiety symptoms were associated with decreased activation in the bilateral lateral PFC during cognitive control performance. Interestingly, these relationships were driven by the n-back task. Our findings suggest that depressive and anxiety symptoms are related to decreased lateral PFC functioning in particular domains of cognitive control among older people.