The efficacy of dyadic interventions for community-dwelling people with dementia and their caregivers: A systematic review and meta-analysis.

Most people with dementia live at home and depend on informal caregivers for care. Both caregivers and persons with dementia can experience negative psychological and behavioural effects as the disease progresses. Non-pharmacological interventions can alleviate these effects and dyadic interventions, involving both caregiver and person with dementia, may be particularly effective. In this systematic review, the effect of dyadic interventions involving community-dwelling persons with dementia and their informal caregivers was researched. This article is an update of a review of dyadic interventions up to 2012 (Van't Leven et al., 2013). Twenty-two randomized controlled trials published between January 2012 and March 2023 met eligibility criteria, representing 3857 dyads. Results of a meta-analysis showed no overall intervention effect. Thirteen studies reported positive intervention effects, 9 studies reported no intervention effects. Intervention content and participant characteristics and knowledge of the disease varied widely between the studies reviewed. Effective interventions were those that matched activities for the person with dementia to their interests and abilities and educating the caregiver about dementia and communication. Interventions of moderate length (3-4 months) tended to be more effective than longer or shorter interventions. Future studies should further explore the factors contributing to the effects of dyadic interventions.

A literature review of outcome and treatment options after acquired brain injury: Suggestions for adult offenders using knowledge from the general population.

BACKGROUND: Acquired brain injury (ABI) is a major health problem, often with negative effects on behaviour and mental health as well as cognition. Prevalence of ABI is exceptionally high among offenders and increases their re-offending risk. Information on risk factors for ABI and its outcomes among offenders that could guide effective treatment for them is, nevertheless, scarce and dispersed. However, there is a more substantial literature about the general population that could inform work with brain-injured offenders, especially when selecting for samples or subgroups with similar relevant characteristics, such as lower socio-economic status (SES), pre-injury lower tested intelligence score (<85) and pre-injury mental health problems. AIMS: To explore brain injury data from non-offender samples of otherwise similar socio-economic and mental health and ability characteristics to offenders then, first, to describe their untreated outcomes and, secondly, outcomes after frequently used interventions in these circumstances, noting factors associated with their effectiveness. METHOD: Three databases were systematically searched for the years 2010-2022; first, using terms for brain injury or damage and cognitive (dys)function, mental health or quality of life. Second, in a separate search, we used these terms and terms for interventions and rehabilitation. In the second review, studies were selected for clear, distinguishable data on age, sex, SES and lifestyle factors to facilitate inferences for offenders. A narrative analytical approach was adopted for both reviews. RESULTS: Samples with characteristics that are typical in offender groups, including lower SES, lower pre-injury intelligence quotient (<85), prior cognitive impairments and prior mental health problems, had poorer cognitive and behavioural outcomes following ABI than those without such additional problems, together with lower treatment adherence. With respect to treatment, adequate motivation and self-awareness were associated with better cognitive and behavioural outcomes than when these were low or absent, regardless of the outcome measured. CONCLUSIONS: More complex pre-injury mental health problems and social disadvantages typical of offenders are associated with poorer post-brain injury recovery. This paper adds to practical knowledge by bringing together work that follows specific outcome trajectories. Overall, succesful ABI-interventions in the general population that aim at pre-injury difficulties comparable to those seen among offenders, show that personalising injury-specific treatments and taking account of these difficulties, maximised positive outcomes.

The effects of a moderate physical activity intervention on physical fitness and cognition in healthy elderly with low levels of physical activity: a randomized controlled trial.

BACKGROUND: Increasing physical activity is one of the most promising and challenging interventions to delay or prevent cognitive decline and dementia. METHODS: We conducted a randomized controlled trial to assess the effects of a physical activity intervention, aimed at increasing step count, in elderly with low levels of physical activity on measures of strength, balance, aerobic capacity, and cognition. Participants were assigned to 9 months of exercise counseling or active control. RESULTS: The intention-to-treat analyses show that the intervention, compared to control, increases the level of physical activity, but has no significant effect on physical fitness and cognition. Those who increased their physical activity with 35% or more show significant improvements in aerobic capacity, gait speed, verbal memory, executive functioning, and global cognition, compared to those who did not achieve a 35% increase. LIMITATIONS: The number of participants that achieved the intended improvement was lower than expected. CONCLUSION: Responder analyses suggest an improvement of physical fitness and cognition in those who achieved an increase in physical activity of at least 35%. TRIAL REGISTRATION: The trial protocol is registered at the Dutch Trial Register NL5675, August 1, 2016.

The long-term relation between physical activity and executive function in the Rotterdam Study.

BACKGROUND: Research on the association between physical inactivity and cognitive decline and dementia is dominated by studies with short-term follow-up, that might be biased by reverse causality. OBJECTIVE: Investigate the long-term association between physical activity, cognition, and the rate of age-associated cognitive decline. METHODS: We investigated the association between late-life physical activity and executive functioning and rate of decline of executive abilities during follow-up of up to 16 years, in 3553 participants of the prospective Rotterdam Study cohort. Measurement took place in 1997-1999, 2002-2004, 2009-2011, and 2014-2015. RESULTS: At baseline (age ± 72 years), higher levels of physical activity were associated with higher levels of executive functioning (adjusted mean difference = 0.03, 95% CI: 0.00 ; 0.06, p = 0.03). This difference remained intact up to 16 years of follow-up. The level of physical activity at baseline was unrelated to the rate of decline of executive abilities over time, in the whole group (adjusted mean difference in changetime*physical activity = 0.00, 95% CI: -0.00 ; 0.01, p = 0.31). However, stratification by APOE genotype showed that the accelerated decline of executive abilities observed in those with the ApoE-ε4 allele might be attenuated by higher levels of physical activity in late adulthood (ApoE-ε4 carriers: Btime*physical activity = 0.01, 95% CI: 0.00 ; 0.01, p = 0.03). CONCLUSION: Higher levels of physical activity in late adulthood are related to higher levels of executive functioning, up to 16 years of follow-up. Accelerated decline of executive abilities observed in those with the ApoE-ε4 allele might be mitigated by higher levels of physical activity.

Acquired Brain Injury and Interventions in the Offender Population: A Systematic Review.

Background and Aims: The prevalence of acquired brain injury (ABI) in offender populations appears much higher than in the general population, being estimated at 50% compared to 12%, respectively. Taking into account ABI-related cognitive and social impairments or behavioral changes in forensic treatments might be relevant and may improve treatment outcomes. The aim of the current review is to summarize and integrate the literature on psychological interventions or treatments for consequences of ABI in the forensic setting. Reviewing this literature could provide crucial information for improving treatment options for offenders with ABI, which may contribute to reducing recidivism. Methods: The PubMed/MEDLINE, PsychInfo, CINAHL, COCHRANE, and Web of Science databases were searched for studies in adult offenders with ABI that evaluated the effect of psychological interventions with a focus on ABI-related impairments and recidivism. Results: This review identified four intervention studies that met the inclusion criteria. These included an adult population (≥18-year-old) in a forensic setting (given the focus of the current review on treatment, defined here as an environment in which offenders are treated while being incarcerated or as outpatients), non-pharmacological treatments and were published in English or Dutch between 2005 and 2020. All studies reported some positive effects of the intervention on interpersonal behavior, cognition and recidivism. The aspects of the interventions that seemed most beneficial included personalized treatment and re-entry plans, support for the individual and their environment and psychoeducation about the effects of ABI. Discussion: Although positive effects were reported in the studies reviewed, all studies had methodological limitations in terms of sample size, study design and outcome measures which affects the strength of the evidence. This limits strong conclusions and generalizability to the entire offender population. Conclusion: Despite high prevalence of ABI in offender populations, interventions in forensic settings seldom address the effect of ABI. The few studies that did take ABI into account reported positive effects, but those results should be interpreted with caution. Future studies are warranted, since this does seem an important venue to improve treatment, which could eventually contribute to reducing recidivism.

Plasma Brain-Derived Neurotropic Factor Levels Are Associated with Aging and Smoking But Not with Future Dementia in the Rotterdam Study.

BACKGROUND: Brain-derived neurotropic factor (BDNF) plays a vital role in neuronal survival and plasticity and facilitates long-term potentiation, essential for memory. Alterations in BDNF signaling have been associated with cognitive impairment, dementia, and Alzheimer's disease. Although peripheral BDNF levels are reduced in dementia patients, it is unclear whether changes in BDNF levels precede or follow dementia onset. OBJECTIVE: In the present study, we examined the association between BDNF plasma levels and dementia risk over a follow-up period of up to 16 years. METHODS: Plasma BDNF levels were assessed in 758 participants of the Rotterdam Study. Dementia was assessed from baseline (1997-1999) to follow-up until January 2016. Associations of plasma BDNF and incident dementia were assessed with Cox proportional hazards models, adjusted for age and sex. Associations between plasma BDNF and lifestyle and metabolic factors are investigated using linear regression. RESULTS: During a follow up of 3,286 person-years, 131 participants developed dementia, of whom 104 had Alzheimer's disease. We did not find an association between plasma BDNF and risk of dementia (adjusted hazard ratio 0.99; 95%CI 0.84-1.16). BDNF levels were positively associated with age (B = 0.003, SD = 0.001, p = 0.002), smoking (B = 0.08, SE = 0.01, p = < 0.001), and female sex (B = 0.03, SE = 0.01, p = 0.03), but not with physical activity level (B = -0.01, SE = 0.01, p = 0.06). CONCLUSION: The findings suggest that peripheral BDNF levels are not associated with an increased risk of dementia.

Sensory Stimulation for Nursing-Home Residents: Systematic Review and Meta-Analysis of Its Effects on Sleep Quality and Rest-Activity Rhythm in Dementia.

INTRODUCTION: Disrupted sleep-wake cycles might be associated with an exacerbation of behavioural disturbances and accelerate disease progression in dementia. The effect of sensory stimulation for improving sleep quality is unclear. METHODS: A systematic literature search was performed and all studies examining the effects of a sensory stimulation intervention (i.e. bright light, massage, acupuncture, animal-assisted interventions) on rest-activity rhythm (RAR) and/or nocturnal restlessness in nursing-home residents with dementia were included. RESULTS: Sensory stimulation was shown to improve nocturnal behavioural restlessness as well as sleep duration and continuation, but the effect on the number of awakenings, RAR, and daytime sleep was negligible. Notable was the high heterogeneity between studies regarding treatments and patients' characteristics and sleep parameters. CONCLUSION: Sleep quality and nocturnal restlessness in nursing-home residents with dementia may benefit from sensory stimulation. An environment with sensory stimulation may prevent or improve sleep disturbances in nursing homes, and thereby contribute to a better quality of life for their patients.

Mood and behavioral problems are important predictors of quality of life of nursing home residents with moderate to severe dementia: A cross-sectional study.

OBJECTIVES: To examine the predictors associated with quality of life of nursing home residents with dementia, in order to identify which predictors are most important and hold most promise for future intervention studies. METHODS/DESIGN: This cross-sectional analysis of data collected in two intervention trials included 143 participants with moderate to severe dementia who resided in 40 psychogeriatric wards in 13 nursing homes. The outcome measure quality of life was assessed with the Qualidem. Predictors examined were demographic factors, cognition, mood, behavioral problems, and comorbid conditions. RESULTS: Linear mixed regression analyses showed that all nine domains of quality of life showed independent (negative) associations with either depression, agitation, apathy, or a combination of these predictors. Agitation, apathy, depression, and the presence of neurological disease explained 50% of the variance in total quality of life. Male gender, psychiatric/mood disorders, and having one or more comorbid conditions was associated with worse social relations, while the presence of comorbid neurological diseases was associated with more social isolation and a worse care relationship. The presence of endocrine/metabolic disorders and pulmonary disorders was associated with less restless tense behavior. CONCLUSIONS: Different domains of quality of life showed different associations, confirming the multidimensionality of quality of life in nursing home residents with dementia. Quality of life is independently associated with mood and behavioral problems, comorbid conditions, and gender. This knowledge may help to identify older persons at risk of a lower quality of life, and to offer targeted interventions to improve quality of life. TRIAL REGISTRATION: Dutch Trial registration NTR5641.

Predictors of care dependency in nursing home residents with moderate to severe dementia: A cross-sectional study.

BACKGROUND: Nursing home residents with dementia show a rapid decline in their ability to perform activities of daily living. This decline is linked to a greater care dependency, which is associated with a reduced quality of life. Care dependency is influenced by multiple predictors, yet current research often focuses on the contribution of a single or a small number of predictors of care dependency. OBJECTIVES: To examine the contribution of multiple predictors in predicting care dependency. DESIGN: The present study analyzed baseline data from a 6-month double-parallel randomized controlled trial which examined the effect of three physical activity interventions on multiple outcomes. SETTING: This study was conducted in eleven nursing homes in Bergen op Zoom, the Netherlands. PARTICIPANTS: In total, 85 nursing home residents with moderate to severe dementia were included in the study, of which 75 were included for analysis. METHODS: Predictors considered were cognitive, physical, neuropsychiatric, demographic, and disease related factors. The outcome measure care dependency was assessed with the Care Dependency Scale and the Erlangen Test of Activities of Daily Living. Linear multilevel regression analyses were used to identify the most important predictors of care dependency. RESULTS: Apathy, physical endurance, number of comorbidities, and global cognition were significant predictors of care dependency. The model explained 66% of the variance in care dependency. Global cognition was a significant predictor of ability to perform activities of daily living and explained 60% percent of its variance. CONCLUSION: The present study shows that multiple predictors (i.e., apathy, cognitive and physical abilities, and disease-related factors) contribute to predicting care dependency. Future research could focus on the effectiveness of multifactorial interventions to maintain the highest possible level of independence in nursing home residents with dementia.

Improving access to a multi-component intervention for caregivers and people with dementia.

Due to the increasing social and economic costs of dementia, there are urgent calls to develop accessible and sustainable care for people with dementia and their caregivers. Multi-component non-pharmacological interventions (NPIs) appear effective in improving or maintaining daily functioning and well-being, but are typically labour-intensive for health care professionals, thus hindering access. The current study aimed to explore the feasibility and acceptability of a novel approach to widen access to NPI by involving caregivers to present part of the intervention and with staff from local support organizations instructed to train the caregivers. Trainers and caregivers were shown to comply with training instructions and the direct intervention costs were low. Feedback from trainers and caregivers was positive and well-being ratings from people with dementia and caregivers remained stable over time and caregivers' sense of competence improved. The findings suggest that involving caregivers and trained non-professionals to provide the intervention is feasible and acceptable and could be a cost-effective solution to improve access to care.

Relationship between social cognition and social behaviour following traumatic brain injury.

Objective: To present an overview of studies that investigated associations between social cognition functions (social cue perception, empathy, understanding intentions) and social behaviour or social outcome following traumatic brain injury (TBI).Methods: The literature search was conducted in the Medline, PsycInfo, Cochrane Library and Web of Science databases. Main criteria for selection were that the participants were adult persons with TBI, social cognition as well as social behaviour or social outcome post-TBI was assessed and correlations between social cognition and social behaviour or outcome were reported. Average correlations were calculated based on weighted summation of the correlations from the individual studies.Results: Of the 511 publications identified in the search, 13 were selected. Ten of these assessed emotion recognition, six assessed understanding of intentions and two assessed empathy. Average correlations between social cognition performance and post-injury social behaviour or outcome were significant for each of the three social cognition functions; poorer performance was associated with poorer outcome. Effect sizes varied from small to moderate (understanding intentions) to moderate (emotion recognition) to large (empathy).Conclusions: The associations were in line with models of social cognition and proposals that impairments in social cognition may underlie social behaviour difficulties and poor social outcome following TBI.

Increased neural response to social rejection in major depression.

BACKGROUND: Being a part of community is critical for survival and individuals with major depressive disorder (MDD) have a greater sensitivity to interpersonal stress that makes them vulnerable to future episodes. Social rejection is a critical risk factor for depression and it is said to increase interpersonal stress and thereby impairing social functioning. It is therefore critical to understand the neural correlates of social rejection in MDD. METHODS: To this end, we scanned 15 medicated MDD and 17 healthy individuals during a modified cyberball passing game, where participants were exposed to increasing levels of social exclusion. Neural responses to increasing social exclusion were investigated and compared between groups. RESULTS: We showed that compared to controls, MDD individuals exhibited greater amygdala, insula, and ventrolateral prefrontal cortex activation to increasing social exclusion and this correlated negatively with hedonic tone and self-esteem scores across all participants. CONCLUSIONS: These preliminary results support the hypothesis that depression is associated with hyperactive response to social rejection. These findings highlight the importance of studying social interactions in depression, as they often lead to social withdrawal and isolation.

Social Behavior and Impairments in Social Cognition Following Traumatic Brain Injury.

OBJECTIVES: The negative effect of changes in social behavior following traumatic brain injury (TBI) are known, but much less is known about the neuropsychological impairments that may underlie and predict these changes. The current study investigated possible associations between post-injury behavior and neuropsychological competencies of emotion recognition, understanding intentions, and response selection, that have been proposed as important for social functioning. METHODS: Forty participants with TBI and 32 matched healthy participants completed a battery of tests assessing the three functions of interest. In addition, self- and proxy reports of pre- and post-injury behavior, mood, and community integration were collected. RESULTS: The TBI group performed significantly poorer than the comparison group on all tasks of emotion recognition, understanding intention, and on one task of response selection. Ratings of current behavior suggested significant changes in the TBI group relative to before the injury and showed significantly poorer community integration and interpersonal behavior than the comparison group. Of the three functions considered, emotion recognition was associated with both post-injury behavior and community integration and this association could not be fully explained by injury severity, time since injury, or education. CONCLUSIONS: The current study confirmed earlier findings of associations between emotion recognition and post-TBI behavior, providing partial evidence for models proposing emotion recognition as one of the pre-requisites for adequate social functioning. (JINS, 2017, 23, 400-411).

A natural language-based presentation of cognitive stimulation to people with dementia in assistive technology: A pilot study.

Currently, an estimated 36 million people worldwide are affected by Alzheimer's disease or related dementias. In the absence of a cure, non-pharmacological interventions, such as cognitive stimulation, which slow down the rate of deterioration can benefit people with dementia and their caregivers. Such interventions have shown to improve well-being and slow down the rate of cognitive decline. It has further been shown that cognitive stimulation in interaction with a computer is as effective as with a human. However, the need to operate a computer often represents a difficulty for the elderly and stands in the way of widespread adoption. A possible solution to this obstacle is to provide a spoken natural language interface that allows people with dementia to interact with the cognitive stimulation software in the same way as they would interact with a human caregiver. This makes the assistive technology accessible to users regardless of their technical skills and provides a fully intuitive user experience. This article describes a pilot study that evaluated the feasibility of computer-based cognitive stimulation through a spoken natural language interface. Prototype software was evaluated with 23 users, including healthy elderly people and people with dementia. Feedback was overwhelmingly positive.

Reduced detection of positive expressions in major depression.

In patients with depression, negative biases have been reported in various cognitive domains, but few studies have examined whether even detection is affected, i.e. are depressed patients more likely to detect the presence of negative stimuli? This study compared detection of sad and happy faces in patients (n=17) and healthy participants (n=18) using an attentional blink task. Patients with depression detected significantly fewer happy faces than matched healthy participants, but for sad faces the group difference was non-significant. The results suggest that depression may affect the detection of positive stimuli.

Deficits in facial emotion recognition indicate behavioral changes and impaired self-awareness after moderate to severe traumatic brain injury.

Traumatic brain injury (TBI) is a leading cause of disability, specifically among younger adults. Behavioral changes are common after moderate to severe TBI and have adverse consequences for social and vocational functioning. It is hypothesized that deficits in social cognition, including facial affect recognition, might underlie these behavioral changes. Measurement of behavioral deficits is complicated, because the rating scales used rely on subjective judgement, often lack specificity and many patients provide unrealistically positive reports of their functioning due to impaired self-awareness. Accordingly, it is important to find performance based tests that allow objective and early identification of these problems. In the present study 51 moderate to severe TBI patients in the sub-acute and chronic stage were assessed with a test for emotion recognition (FEEST) and a questionnaire for behavioral problems (DEX) with a self and proxy rated version. Patients performed worse on the total score and on the negative emotion subscores of the FEEST than a matched group of 31 healthy controls. Patients also exhibited significantly more behavioral problems on both the DEX self and proxy rated version, but proxy ratings revealed more severe problems. No significant correlation was found between FEEST scores and DEX self ratings. However, impaired emotion recognition in the patients, and in particular of Sadness and Anger, was significantly correlated with behavioral problems as rated by proxies and with impaired self-awareness. This is the first study to find these associations, strengthening the proposed recognition of social signals as a condition for adequate social functioning. Hence, deficits in emotion recognition can be conceived as markers for behavioral problems and lack of insight in TBI patients. This finding is also of clinical importance since, unlike behavioral problems, emotion recognition can be objectively measured early after injury, allowing for early detection and treatment of these problems.

Cognitive stimulation by caregivers for people with dementia.

Cognitive stimulation (CS) is a psychological intervention for people with dementia aimed at maintaining cognitive functioning. CS provided by caregivers would allow long-term maintenance without greatly increasing demands on health services, but raises questions concerning treatment fidelity and acceptability, which were investigated in this study. Caregivers of home-living people with dementia were trained to provide CS activities to their relative with dementia. Recordings of intervention sessions and analysis of training manuals suggested adequate delivery of the intervention. Dyads continued with the activities after caregiver training had stopped. In addition, presentation of the activities without supervision from a health care professional had no detrimental effect on well-being in the caregiver or the person with dementia. The majority of caregivers indicated that, even though they experienced some burden from doing the activities with their relative, they themselves had also benefited from the intervention and intended to continue with some of the activities.

Abnormal neural responses to social exclusion in schizophrenia.

Social exclusion is an influential concept in politics, mental health and social psychology. Studies on healthy subjects have implicated the medial prefrontal cortex (mPFC), a region involved in emotional and social information processing, in neural responses to social exclusion. Impairments in social interactions are common in schizophrenia and are associated with reduced quality of life. Core symptoms such as delusions usually have a social content. However little is known about the neural underpinnings of social abnormalities. The aim of this study was to investigate the neural substrates of social exclusion in schizophrenia. Patients with schizophrenia and healthy controls underwent fMRI while participating in a popular social exclusion paradigm. This task involves passing a 'ball' between the participant and two cartoon representations of other subjects. The extent of social exclusion (ball not being passed to the participant) was parametrically varied throughout the task. Replicating previous findings, increasing social exclusion activated the mPFC in controls. In contrast, patients with schizophrenia failed to modulate mPFC responses with increasing exclusion. Furthermore, the blunted response to exclusion correlated with increased severity of positive symptoms. These data support the hypothesis that the neural response to social exclusion differs in schizophrenia, highlighting the mPFC as a potential substrate of impaired social interactions.

Social cognition impairments in relation to general cognitive deficits, injury severity, and prefrontal lesions in traumatic brain injury patients.

Impairments in social behavior are frequently found in moderate to severe traumatic brain injury (TBI) patients and are associated with an unfavorable outcome with regard to return to work and social reintegration. Neuropsychological tests measuring aspects of social cognition are thought to be sensitive to these problems. However, little is known about the effect of general cognitive problems on these tests, nor about their sensitivity to injury severity and frontal lesions. In the present study 28 chronic TBI patients with a moderate to severe TBI were assessed with tests for social cognition (emotion recognition, Theory of Mind, and empathy), and for general, non-social cognition (memory, mental speed, attention, and executive function). The patients performed significantly worse than healthy controls on all measures, with the highest effect size for the emotion recognition test, the Facial Expressions of Emotion-Stimuli and Tests (FEEST). Correlation analyses yielded no significant (partial) correlations between social and non-social cognition tests. Consequently, poor performance on social cognition tests was not due to general cognitive deficits. In addition, the emotion recognition test was the only measure that was significantly related to post-traumatic amnesia (PTA) duration, Glasgow Coma Scale (GCS) score, and the presence of prefrontal lesions. Hence, we conclude that social cognition tests are a valuable supplement to a standard neuropsychological examination, and we strongly recommend the incorporation of measurements of social cognition in clinical practice. Preferably, a broader range of social cognition tests would be applied, since our study demonstrated that each of the measures represents a unique aspect of social cognition, but if capacity is limited, at least a test for emotion recognition should be included.

Detection of emotional faces is modulated by the direction of eye gaze.

Emotionally expressive faces have shown enhanced detectability over neutral faces, but little is known about the effect of eye gaze on detecting the presence of emotional faces. Emotional expressions and gaze direction are both cues to the intentions of another person, and gaze direction has been shown to affect recognition accuracy and perceived intensity of emotional faces. The current study showed that fearful faces were detected more frequently with an averted gaze than with a direct gaze in an attentional blink task, whereas angry and happy faces were detected more frequently with a direct gaze than with an averted gaze. The results are in line with the shared signal hypothesis and appraisal theory and suggest that selection for awareness was based on a rapid evaluation of the intentions of another person as conveyed by their facial expression and gaze direction.