The usability and reliability of a smartphone application for monitoring future dementia risk in ageing UK adults.

BACKGROUND: The rising number of dementia diagnoses and imminent adoption of disease-modifying treatments necessitate innovative approaches to identify individuals at risk, monitor disease course and intervene non-pharmacologically earlier in the disease course. Digital assessments of dementia risk and cognitive function have the potential to outperform traditional in-person assessments in terms of their affordability, accuracy and longitudinal tracking abilities. However, their accessibility and reliability in older adults is unclear. AIMS: To evaluate the usability and reliability of a smartphone assessment of lifestyle and cognitive factors relevant to dementia risk in a group of UK-based older adults. METHOD: Cognitively healthy adults (n = 756) recruited through the Dementias Platform UK Great Minds volunteer register completed three assessments of cognitive function and dementia risk over a 3-month period and provided usability feedback on the Five Lives smartphone application (app). We evaluated cognitive test scores for age, gender and higher education effects, normality distributions, test-retest reliability and their relationship with participants' lifestyle dementia risk factors. RESULTS: Participants found the app 'easy to use', 'quick to complete' and 'enjoyable'. The cognitive tests showed normal or near-to-normal distributions, variable test-retest reliabilities and age-related effects. Only tests of verbal ability showed gender and education effects. The cognitive tests did not correlate with lifestyle dementia risk scores. CONCLUSIONS: The Five Lives assessment demonstrates high usability and reliability among older adults. These findings highlight the potential of digital assessments in dementia research and clinical practice, enabling improved accessibility and better monitoring of cognitive health on a larger scale than traditional in-person assessments.

Barriers to brain health behaviours: results from the Five Lives Brain Health Ireland Survey.

Modifiable risk factors for dementia remain prevalent in Ireland. A detailed examination of barriers to risk reduction behaviours in an Irish context has heretofore been lacking. Many existing studies examining barriers to brain health behaviours fail to examine how they might vary across different modifiable risk factors. This study undertook a detailed assessment of barriers to individual risk reduction behaviours. As existing research suggests that barriers may vary across sociodemographic factors, we sought to investigate the distribution of barriers across age, gender, educational status, and household income. The Five Lives Brain Health Ireland Survey is a cross-sectional survey that was distributed online amongst a non-patient population. The survey captured the following: (1) Sociodemographic factors; (2) Barriers to brain health behaviours; (3) Exposure to, and knowledge of, modifiable risk factors for dementia, namely diet, social interaction, exercise, hypertension, sleep, current low mood/depression, current smoking, alcohol consumption, cognitive stimulation, hearing impairment, diabetes, air pollution, and head injury; (4) Participants' perceptions regarding potential for dementia prevention, and risk reduction. Lack of motivation was the most prevalent barrier to consuming a healthy diet (64%, n = 213), physical activity (77.7%, n = 167), smoking cessation (68%, n = 85), and moderation of alcohol intake (56.3%, n = 67). Practical factors were the most prevalent barriers to addressing low mood (56.5%, n = 87), air pollution (30.1%, n = 58), hearing impairment (63.8%, n = 44), diabetes (11.1%, n = 5), and head injury (80%, n = 8). Emotional factors were the most prevalent barriers to engaging in mentally stimulating activity (56.9%, n = 66), social activity (54.9%, n = 302), and good sleep (70.1%, n = 129). Lack of knowledge was the most prevalent barrier to hypertension control (14.4%, n = 29). Distribution of barriers varied across age, gender, educational status, and household income. This study investigated barriers to lifestyle change to improve brain health in an Irish sample of adults aged 50 and above. Detailed subtyping of barriers, as well as examination of differences according to age, gender, education, and income were undertaken. The heterogeneity of barriers to brain health behaviours revealed in this study highlights the necessity to tailor public health interventions to their target population, taking into account the gender, age, educational status, and income of recipients.

Modifiable risk factors for dementia, and awareness of brain health behaviors: Results from the Five Lives Brain Health Ireland Survey (FLBHIS).

Up to 40% of dementias globally are attributable to modifiable risk factors. Many existing studies examining attitudes to brain health are limited by a failure to consider a range of pertinent risk factors and associated barriers to protective behaviors. In Ireland, self-reported knowledge of dementia is poor compared to other conditions. In this context, the current study aimed to explore exposure to and awareness of specific modifiable risk factors for dementia. We also aimed to investigate whether exposure to these risk factors is associated with demographic and socioeconomic factors. A cross-sectional survey was administered to 555 voluntary participants in February 2022. The survey captured the following information: (1) Sociodemographic factors; (2) Exposure to, as well as knowledge of modifiable risk factors for dementia, namely diet, social interaction, exercise, hypertension, sleep, depression, smoking, alcohol consumption, cognitive stimulation, hearing impairment, diabetes, air pollution, and head injury. The study population comprised 551 participants (50.3% male; 49.6% female). Mean age was 59.7 years. Modifiable risk factors for dementia were prevalent. Relative to females, male gender was significantly associated with multiple risk factors. Whilst 65.6% of participants believed that lifestyle improvements can decrease a person's risk of developing dementia, only 31.4% believed that dementia could be prevented. Head injury (90.9%, n = 500), low mental stimulation (85.3%, n = 469), and alcohol consumption (77.8%, n = 428) were the three most commonly recognized risk factors. Awareness was significantly greater in both university groups (undergraduate and postgraduate) for multiple risk factors. Our findings demonstrate that the distribution of exposure to modifiable risk factors for dementia is unequal across gender and age groups, and that awareness levels vary across risk factors. These findings highlight that focus surrounding dementia prevention should shift toward individual risk profiling and should be tailored toward an individual's specific needs.

Right but not left angular gyrus modulates the metric component of the mental body representation: a tDCS study.

The parietal lobes contribute to body-space representation. The present work aims at characterizing the functional role of the inferior parietal lobe in body-space representation and at studying the different roles of the angular gyrus in the right and left hemisphere. We conducted three separate transcranial direct current stimulation (tDCS) experiments using "tactile distance task" as an implicit measure of body representation. Whereas anodal tDCS on the right angular gyrus influences vocal reaction times (vRT) for stimuli delivered on the ipsilateral body parts without changes of accuracy, right tDCS improved both vRT and accuracy for tactile stimuli on the contralateral limbs. Sham or left parietal anodal tDCS had no effect. These evidences support the view that right parietal areas have a crucial role in the metric component of the body representation.

Modulating behavioral inhibition by tDCS combined with cognitive training.

Cognitive training is an effective tool to improve a variety of cognitive functions, and a small number of studies have now shown that brain stimulation accompanying these training protocols can enhance their effects. In the domain of behavioral inhibition, little is known about how training can affect this skill. As for transcranial direct current stimulation (tDCS), it was previously found that stimulation over the right inferior frontal gyrus (rIFG) facilitates behavioral inhibition performance and modulates its electrophysiological correlates. This study aimed to investigate this behavioral facilitation in the context of a learning paradigm by giving tDCS over rIFG repetitively over four consecutive days of training on a behavioral inhibition task (stop signal task (SST)). Twenty-two participants took part; ten participants were assigned to receive anodal tDCS (1.5 mA, 15 min), 12 were assigned to receive training but not active stimulation. There was a significant effect of training on learning and performance in the SST, and the integration of the training and rIFG-tDCS produced a more linear learning slope. Better performance was also found in the active stimulation group. Our findings show that tDCS-combined cognitive training is an effective tool for improving the ability to inhibit responses. The current study could constitute a step toward the use of tDCS and cognitive training as a therapeutic tool for cognitive control impairments in conditions such as attention-deficit hyperactivity disorder (ADHD) or schizophrenia.

Oppositional transcranial direct current stimulation (tDCS) of parietal substrates of attention during encoding modulates episodic memory.

Effective learning requires that attentional resources be focused on target information and withheld from irrelevant events in the learner's surroundings. This requires engagement of the brain substrates of selective attention and the concurrent disengagement of brain substrates of orienting toward changes in the environment. In the present study, we attempted to modulate activation of cortical substrates of attention during learning by physiological intervention, using transcranial direct current stimulation (tDCS). To effect adversarial modulation, we applied anodal stimulation directed toward left intraparietal sulcus/superior parietal cortex (IPS/SPL; a substrate of selective attention) and cathodal stimulation directed toward right inferior parietal cortex (IPL; a substrate of orienting). Such stimulation during study of verbal materials led to superior subsequent recognition memory relative to the opposite polarity of stimulation. To our knowledge, this is the first application of direct current stimulation to parietal regions implicated in different forms of attention in an oppositional manner in order to modulate learning in a verbal recognition memory task. Additionally, these results may have practical implications for the development of interventions to benefit persons with various types of attentional deficits.

Modulating oscillatory brain activity correlates of behavioral inhibition using transcranial direct current stimulation.

OBJECTIVE: Studies have mainly documented behavioral changes induced by transcranial direct current stimulation (tDCS), but recently cortical modulations of tDCS have also been investigated. Our previous work revealed behavioral inhibition modulation by anodal tDCS over the right inferior frontal gyrus (rIFG); however, the electrophysiological correlates underlying this stimulation montage have yet to be established. The current work aimed to evaluate the distribution of neuronal oscillations changes following anodal tDCS over rIFG coupled with cathodal tDCS over left orbitofrontal cortex (lOFC) using spectral power analysis. METHODS: Healthy subjects underwent sham and real tDCS (15 min, 1.5 mA, anodal rIFG; cathodal lOFC) stimulation conditions in a single-blind, placebo-controlled cross-over trial. Following tDCS session, resting EEG recordings were collected during 15 min. RESULTS: Analysis showed a significant and selective diminution of the power of theta band. The theta diminution was observed in the rIFG area (represented the anode electrode), and was not found in the lOFC area (represented the cathode electrode). A significant effect was observed only in the theta but not in other bands. CONCLUSIONS: These results are the first demonstration of modulating oscillatory activity as measured by EEG with tDCS over rIFG in general, and documenting theta band reduction with this montage in particular. SIGNIFICANCE: Our results may explain the improvement in behavioral inhibition reported in our previous work, and although this study was conducted with healthy subjects, the findings suggest that tDCS may also modulate electrophysiological changes among ADHD patients, where decreasing theta activity is the target of neuro-feedback methods aimed to improve cognitive control.

tDCS polarity effects in motor and cognitive domains: a meta-analytical review.

In vivo effects of transcranial direct current stimulation (tDCS) have attracted much attention nowadays as this area of research spreads to both the motor and cognitive domains. The common assumption is that the anode electrode causes an enhancement of cortical excitability during stimulation, which then lasts for a few minutes thereafter, while the cathode electrode generates the opposite effect, i.e., anodal-excitation and cathodal-inhibition effects (AeCi). Yet, this dual-polarity effect has not been observed in all tDCS studies. Here, we conducted a meta-analytical review aimed to investigate the homogeneity/heterogeneity of the effect sizes of the AeCi dichotomy in both motor and cognitive functions. The AeCi effect was found to occur quite commonly with motor investigations and rarely in cognitive studies. When the anode electrode is applied over a non-motor area, in most cases, it will cause an excitation as measured by a relevant cognitive or perceptual task; however, the cathode electrode rarely causes an inhibition. We found homogeneity in motor studies and heterogeneity in cognitive studies with the electrode's polarity serving as a moderator that can explain the source of heterogeneity in cognitive studies. The lack of inhibitory cathodal effects might reflect compensation processes as cognitive functions are typically supported by rich brain networks. Further insights as to the polarity and domain interaction are offered, including subdivision to different classes of cognitive functions according to their likelihood of being affected by stimulation.

Activation of inhibition: diminishing impulsive behavior by direct current stimulation over the inferior frontal gyrus.

A common feature of human existence is the ability to reverse decisions after they are made but before they are implemented. This cognitive control process, termed response inhibition, refers to the ability to inhibit an action once initiated and has been localized to the right inferior frontal gyrus (rIFG) based on functional imaging and brain lesion studies. Transcranial direct current stimulation (tDCS) is a brain stimulation technique that can facilitate as well as impair cortical function. To explore whether response inhibition can be improved through rIFG electrical stimulation, we administered focal tDCS before subjects performed the stop signal task (SST), which measures response inhibition. Notably, activation of the rIFG by unilateral anodal stimulation significantly improved response inhibition, relative to a sham condition, whereas the same tDCS protocol did not affect response time in the go trials of the SST and in a control task. Furthermore, the SST was not affected by tDCS at a control site, the right angular gyrus. Our results are the first demonstration of response inhibition improvement with brain stimulation over rIFG and further confirm the rIFG involvement in this task. Although this study was conducted in healthy subjects, present findings with anodal rIFG stimulation support the use of similar paradigms for the treatment of cognitive control impairments in pathological conditions.

Finding the hidden faces: schizophrenic patients fare worse than healthy subjects.

Humans have a special ability to recognize human faces that transcends and is separate from the usual discrimination abilities of the visual system. Schizophrenia patients are known to have an impaired ability to recognize facial affect, a deficit that may stem from a more profound problem of face identification and perception. The special skill of detecting human faces relies upon numerous capabilities, including gestalt perception, "filling-in", and proper gaze scanning, facilities that recent research has shown to be deficient in schizophrenia patients. We therefore hypothesized that schizophrenia patients have a deficit in their perception and structural analysis of human faces that will manifest in their difficulty in detecting faces hidden within neutral pictures. We tested the ability of 35 schizophrenia patients and 32 healthy controls at detecting hidden human faces and animals or animal faces hidden within eight pictures. Overall, the patients recognized fewer items compared to controls, however, it was specifically the human faces in which this difference was significant, suggesting that schizophrenic patients have a specific deficit in their human face recognition system.