Relating constructs of attention and working memory to social withdrawal in Alzheimer’s disease and schizophrenia: issues regarding paradigm selection

Basal forebrain parvalbumin neurons modulate vigilant attention and rescue deficits produced by sleep deprivation

Attention is impaired in many neuropsychiatric disorders, as well as by sleep disruption, leading to decreased workplace productivity and increased risk of accidents. Thus, understanding the neural substrates is important. Here we test the hypothesis that basal forebrain neurons that contain the calcium-binding protein parvalbumin modulate vigilant attention in mice. Furthermore, we test whether increasing the activity of basal forebrain parvalbumin neurons can rescue the deleterious effects of sleep deprivation on vigilance. A lever release version of the rodent psychomotor vigilance test was used to assess vigilant attention. Brief and continuous low-power optogenetic excitation (1 s, 473 nm @ 5 mW) or inhibition (1 s, 530 nm @ 10 mW) of basal forebrain parvalbumin neurons was used to test the effect on attention, as measured by reaction time, under control conditions and following 8 hr of sleep deprivation by gentle handling. Optogenetic excitation of basal forebrain parvalbumin neurons that preceded the cue light signal by 0.5 s improved vigilant attention as indicated by quicker reaction times. By contrast, both sleep deprivation and optogenetic inhibition slowed reaction times. Importantly, basal forebrain parvalbumin excitation rescued the reaction time deficits in sleep-deprived mice. Control experiments using a progressive ratio operant task confirmed that optogenetic manipulation of basal forebrain parvalbumin neurons did not alter motivation. These findings reveal for the first time a role for basal forebrain parvalbumin neurons in attention, and show that increasing their activity can compensate for disruptive effects of sleep deprivation.

Digital behavioural signatures reveal trans-diagnostic clusters of Schizophrenia and Alzheimer's disease patients

The current neuropsychiatric nosological categories underlie pragmatic treatment choice, regulation and clinical research but does not encompass biological rationale. However, subgroups of patients suffering from schizophrenia or Alzheimer's disease have more in common than the neuropsychiatric nature of their condition, such as the expression of social dysfunction. The PRISM project presents here initial quantitative biological insights allowing the first steps toward a novel trans-diagnostic classification of psychiatric and neurological symptomatology intended to reinvigorate drug discovery in this area. In this study, we applied spectral clustering on digital behavioural endpoints derived from passive smartphone monitoring data in a subgroup of Schizophrenia and Alzheimer's disease patients, as well as age matched healthy controls, as part of the PRISM clinical study. This analysis provided an objective social functioning characterization with three differential clusters that transcended initial diagnostic classification and was shown to be linked to quantitative neurobiological parameters assessed. This emerging quantitative framework will both offer new ways to classify individuals in biologically homogenous clusters irrespective of their initial diagnosis, and also offer insights into the pathophysiological mechanisms underlying these clusters.

The Influence of Probiotic Supplementation on the Obesity Indexes, Neuroinflammatory and Oxidative Stress Markers, Gut Microbial Diversity, and Working Memory in Obese Thai Children

Obesity is a worldwide health problem with a complex interaction between gut microbiota and cognition. Several studies have demonstrated that probiotic treatments improve characteristics linked to obesity. The present study aimed to evaluate the effects of probiotic supplementation on the obesity indexes, inflammatory and oxidative stress markers, gut microbiota, and working memory in obese children. Ten obese children were assigned to receive the probiotics (8 × 109 CFU of Lactobacillus paracasei HII01 and Bifidobacterium animalis subsp. lactis) for 12 weeks. Demographic data were recorded. Urine and fecal samples were collected to evaluate biomarkers related to obesity and cognition. Behavioral working memory was assessed using the visual n-back test. Electroencephalography was employed to measure electrical activity during the visual n-back test. All parameters were evaluated at the baseline and after 12 weeks. The results revealed that probiotic supplementation significantly altered some gut microbial metabolites, gut microbiota, total antioxidant capacity, and neuroinflammatory markers. However, no significant changes were observed in the visual n-back test or electroencephalographic recordings after 12 weeks. In conclusion, the use of probiotics might be an alternative treatment that could improve the gut microbial ecosystem and microbial metabolites, as well as host antioxidant and neuroinflammation levels. The preliminary results indicated that further detailed prolonged studies are needed in order to determine the beneficial effects of the studied probiotics.

Effects of ortho-eugenol on anxiety, working memory and oxidative stress in mice

Ortho-eugenol is a synthetic derivative from eugenol, the major compound of clove essential oil, which has demonstrated antidepressant and antinociceptive effects in pioneering studies. Additionally, its effects appear to be dependent on the noradrenergic and dopaminergic systems. Depression and anxiety disorders are known to share a great overlap in their pathophysiology, and many drugs are effective in the treatment of both diseases. Furthermore, high levels of anxiety are related to working memory deficits and increased oxidative stress. Thus, in this study we investigated the effects of acute treatment of ortho-eugenol, at 50, 75 and 100 mg/kg, on anxiety, working memory and oxidative stress in male Swiss mice. Our results show that the 100 mg/kg dose increased the number of head-dips and reduced the latency in the hole-board test. The 50 mg/kg dose reduced malondialdehyde levels in the prefrontal cortex and the number of Y-maze entries compared to the MK-801-induced hyperlocomotion group. All doses reduced nitrite levels in the hippocampus. It was also possible to assess a statistical correlation between the reduction of oxidative stress and hyperlocomotion after the administration of ortho-eugenol. However, acute treatment was not able to prevent working memory deficits. Therefore, the present study shows that ortho-eugenol has an anxiolytic and antioxidant effect, and was able to prevent substance-induced hyperlocomotion. Our results contribute to the elucidation of the pharmacological profile of ortho-eugenol, as well as to direct further studies that seek to investigate its possible clinical applications.

Wider and Stronger Inhibitory Ring of the Attentional Focus in Schizophrenia

Anomalies of attentional selection have been repeatedly described in individuals with schizophrenia spectrum disorders. However, a precise analysis of their ability to inhibit irrelevant visual information during attentional selection is not documented. Recent behavioral as well as neurophysiological and computational evidence showed that attentional search among different competing stimuli elicits an area of suppression in the immediate surrounding of the attentional focus. In the present study, the strength and spatial extension of this surround suppression were tested in individuals with schizophrenia and neurotypical controls. Participants were asked to report the orientation of a visual "pop-out" target, which appeared in different positions within a peripheral array of non-target stimuli. In half of the trials, after the target appeared, a probe circle circumscribed a non-target stimulus at various target-to-probe distances; in this case, participants were asked to report the probe orientation instead. Results suggest that, as compared to neurotypical controls, individuals with schizophrenia showed stronger and spatially more extended filtering of visual information in the areas surrounding their attentional focus. This increased filtering of visual information outside the focus of attention might potentially hamper their ability to integrate different elements into coherent percepts and influence higher order behavioral, affective, and cognitive domains.

Serum Level of Growth-Associated Protein 43 Is Associated with First-Episode Schizophrenia Patients without Antipsychotic Drugs Treatment

Nerve growth-associated protein 43 (GAP43) is closely related to neural development, axon regeneration, and synaptic reconstruction and is one of the important markers of neuronal damage. Therefore, in our study, enzyme-linked immunosorbent assay (ELISA) was used to analyze the serum level of GAP43 protein in schizophrenia patients (n = 188), healthy controls (n = 200), and bipolar disorder patients (n = 200). The positive and negative syndrome scale (PANSS) was used to evaluate the mental status of schizophrenia patients, and the Scale of Social Function in Psychosis Inpatients (SSPI) was used to evaluate the social function of schizophrenia patients. According to this study, we found the serum GAP43 level was significantly higher in schizophrenia patients than in bipolar disorder patients, while serum GAP43 levels in bipolar disorder patients were significantly higher than those in control group. When the cut-off value was set as 2.328 ng/mL, the area under the curve (AUC) of serum GAP43 was 0.7795 (95% CI: 0.7431-0.8158) for diagnosis of schizophrenia. The sensitivity and specificity were 92.02% and 65.25%, respectively. However, no correlation between serum GAP43 and the total scores of PANSS scale in schizophrenia patients as well as between serum GAP43 level and SSPI were observed. Therefore, we believe that GAP43 may be a potential diagnostic marker for schizophrenia.

Cognitive Training to Enhance Aphasia Therapy (Co-TrEAT): A Feasibility Study

Persons with aphasia (PWA) often have deficits in cognitive domains such as working memory (WM), which are negatively correlated with recovery, and studies have targeted WM deficits in aphasia therapy. To our knowledge, however, no study has examined the efficacy of multi-modal training which includes both WM training and targeted language therapy. This pilot project examined the feasibility and preliminary efficacy of combining WM training and naming therapy to treat post-stroke PWA. Chronic PWA were randomly assigned to either the a) Phonological Components Analysis (PCA) and WM intervention (WMI) condition (i.e., a computerized adaptive dual n-back task), or b) PCA and active control condition (WMC). Participants received face-to-face PCA therapy 3 times/week for 5 weeks, and simultaneously engaged in WM training or the active control condition five times/week, independently at home. Six PWA were enrolled, 3 in each condition. Feasibility metrics were excellent for protocol compliance, retention rate and lack of adverse events. Recruitment was less successful, with insufficient participants for group analyses. Participants in the WMI (but not the WMC) condition demonstrated a clinically significant (i.e., > 5 points) improvement on the Western Aphasia Battery- Aphasia Quotient (WAB-R AQ) and Boston Naming Test after therapy. Given the small sample size, the performance of two individuals, matched on age, education, naming accuracy pre-treatment, WAB-R AQ and WM abilities was compared. Participant WMI-3 demonstrated a notable increase in WM training performance over the course of therapy; WMC-2 was the matched control. After therapy, WMI-3's naming accuracy for the treated words improved from 30 to 90% (compared to 30–50% for WMC-2) with a 7-point WAB-R AQ increase (compared to 3 for WMC-2). Improvements were also found for WMI-3 but not for WMC-2 on ratings of communicative effectiveness, confidence and some conversation parameters in discourse. This feasibility study demonstrated excellent results for most aspects of Co-TrEAT. Recruitment rate, hampered by limited resources, must be addressed in future trials; remotely delivered aphasia therapy may be a possible solution. Although no firm conclusions can be drawn, the case studies suggest that WM training has the potential to improve language and communication outcomes when combined with aphasia therapy.

Neural correlates of individual variation in two-back working memory and the relationship with fluid intelligence

Working memory has been examined extensively using the N-back task. However, less is known about the neural bases underlying individual variation in the accuracy rate (AR) and reaction time (RT) as metrics of N-back performance. Whereas AR indexes the overall performance, RT may more specifically reflect the efficiency in updating target identify. Further, studies have associated fluid intelligence (Gf) with working memory, but the cerebral correlates shared between Gf and N-back performance remain unclear. We addressed these issues using the Human Connectome Project dataset. We quantified the differences in AR (critical success index or CSI) and RT between 2- and 0-backs (CSI_2–0 and RT_2–0) and identified the neural correlates of individual variation in CSI_2–0, RT_2–0, and Gf, as indexed by the number of correct items scored in the Raven’s Standard Progressive Matrices (RSPM) test. The results showed that CSI_2–0 and RT_2–0 were negatively correlated, suggesting that a prolonged response time did not facilitate accuracy. At voxel p < 0.05, FWE-corrected, the pre-supplementary motor area (preSMA), bilateral frontoparietal cortex (biFPC) and right anterior insula (rAI) showed activities in negative correlation with CSI_2–0 and positive correlation with RT_2–0. In contrast, a cluster in the dorsal anterior cingulate cortex (dACC) bordering the SMA showed activities in positive correlation with CSI_2–0 and negative correlation with RT_2–0. Further, path analyses showed a significant fit of the model dACC → RT_2–0 → CSI_2–0, suggesting a critical role of target switching in determining performance accuracy. Individual variations in RT_2–0 and Gf were positively correlated, although the effect size was small (f² = 0.0246). RT_2–0 and Gf shared activities both in positive correlation with the preSMA, biFPC, rAI, and dorsal precuneus. These results together suggest inter-related neural substrates of individual variation in N-back performance and highlight a complex relationship in the neural processes supporting 2-back and RSPM performance.

Acute cognitive impairment after traumatic brain injury predicts the occurrence of brain atrophy patterns similar to those observed in Alzheimer's disease

Traumatic brain injuries (TBIs) are often followed by persistent structural brain alterations and by cognitive sequalae, including memory deficits, reduced neural processing speed, impaired social function, and decision-making difficulties. Although mild TBI (mTBI) is a risk factor for Alzheimer's disease (AD), the extent to which these conditions share patterns of macroscale neurodegeneration has not been quantified. Comparing such patterns can not only reveal how the neurodegenerative trajectories of TBI and AD are similar, but may also identify brain atrophy features which can be leveraged to prognosticate AD risk after TBI. The primary aim of this study is to systematically map how TBI affects white matter (WM) and gray matter (GM) properties in AD-analogous patterns. Our findings identify substantial similarities in the regional macroscale neurodegeneration patterns associated with mTBI and AD. In cerebral GM, such similarities are most extensive in brain areas involved in memory and executive function, such as the temporal poles and orbitofrontal cortices, respectively. Our results indicate that the spatial pattern of cerebral WM degradation observed in AD is broadly similar to the pattern of diffuse axonal injury observed in TBI, which frequently affects WM structures like the fornix, corpus callosum, and corona radiata. Using machine learning, we find that the severity of AD-like brain changes observed during the chronic stage of mTBI can be accurately prognosticated based on acute assessments of post-traumatic mild cognitive impairment. These findings suggest that acute post-traumatic cognitive impairment predicts the magnitude of AD-like brain atrophy, which is itself associated with AD risk.

In Vivo Characterization of Cortical and White Matter Microstructural Pathology in Growth Hormone-Secreting Pituitary Adenoma

Background

The growth hormone (GH) and insulin-like-growth factor 1 (IGF-1) axis has long been recognized for its critical role in brain growth, development. This study was designed to investigate microstructural pathology in the cortex and white matter in growth hormone-secreting pituitary adenoma, which characterized by excessive secretion of GH and IGF-1.

Methods

29 patients with growth hormone-secreting pituitary adenoma (acromegaly) and 31 patients with non-functional pituitary adenoma as controls were recruited and assessed using neuropsychological test, surface-based morphometry, T1/T2-weighted myelin-sensitive magnetic resonance imaging, neurite orientation dispersion and density imaging, and diffusion tensor imaging.

Results

Compared to controls, we found 1) acromegaly had significantly increased cortical thickness throughout the bilateral cortex (pFDR < 0.05). 2) T1/T2-weighted ratio in the cortex were decreased in the bilateral occipital cortex and pre/postcentral central gyri but increased in the bilateral fusiform, insular, and superior temporal gyri in acromegaly (pFDR < 0.05). 3) T1/T2-weighted ratio were decreased in most bundles, and only a few areas showed increases in acromegaly (pFDR < 0.05). 4) Neurite density index (NDI) was significantly lower throughout the cortex and bundles in acromegaly (pTFCE < 0.05). 5) lower fractional anisotropy (FA) and higher mean diffusivity (MD), axial diffusivity (AD) and radial diffusivity (RD) in extensive bundles in acromegaly (pTFCE < 0.05). 6) microstructural pathology in the cortex and white matter were associated with neuropsychological dysfunction in acromegaly.

Conclusions

Our findings suggested that long-term persistent and excess serum GH/IGF-1 levels alter the microstructure in the cortex and white matter in acromegaly, which may be responsible for neuropsychological dysfunction.

Dynamic functional connectome predicts individual working memory performance across diagnostic categories

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We created transdiagnostic predictive working memory models using connectome-based predictive modeling (CPM).

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Dynamic functional connectivity-based CPM models successfully predicted working memory.

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Static functional connectivity-based CPM models fell short in prediction.

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Frontoparietal, somato-motor, default mode and visual networks contributed most to prediction.

Working memory impairment is a common feature of psychiatric disorders. Although its neural mechanisms have been extensively examined in healthy subjects or individuals with a certain clinical condition, studies investigating neural predictors of working memory in a transdiagnostic sample are scarce. The objective of this study was to create a transdiagnostic predictive working memory model from whole-brain functional connectivity using connectome-based predictive modeling (CPM), a recently developed machine learning approach. Resting-state functional MRI data from 242 subjects across 4 diagnostic categories (healthy controls and individuals with schizophrenia, bipolar disorder, and attention deficit/hyperactivity) were used to construct dynamic and static functional connectomes. Spatial working memory was assessed by the spatial capacity task. CPM was conducted to predict individual working memory from dynamic and static functional connectivity patterns. Results showed that dynamic connectivity-based CPM models successfully predicted overall working memory capacity and accuracy as well as mean reaction time, yet their static counterparts fell short in the prediction. At the neural level, we found that dynamic connectivity of the frontoparietal and somato-motor networks were negatively correlated with working memory capacity and accuracy, and those of the default mode and visual networks were positively associated with mean reaction time. Moreover, different feature selection thresholds, parcellation strategies and model validation methods as well as diagnostic categories did not significantly influence the prediction results. Our findings not only are coherent with prior reports that dynamic functional connectivity encodes more behavioral information than static connectivity, but also help advance the translation of cognitive “connectome fingerprinting” into real-world application.

Dual n-back working memory training evinces superior transfer effects compared to the method of loci

Working memory (WM) training is a prevalent intervention for multiple cognitive deficits, however, the transfer effects to other cognitive tasks from gains in WM induced by different training techniques still remains controversial. Therefore, the current study recruited three groups of young adults to investigate the memory training transference, with N-back group (NBG) (n = 50) training on dual n-back task, Memory Palace group (MPG) (n = 50) on method of loci, and a blank control group (BCG) (n = 48) receiving no training. Our results showed that both training groups separately improved WM capacity on respective trained task. For untrained tasks, both training groups enhanced performance on digit-span task, while on change detection task, significant improvement was only observed in NBG. In conclusion, while both techniques can be used as effective training methods to improve WM, the dual n-back task training method, perhaps has a more prominent transfer effect than that of method of loci.

Prefrontal cortex activation during working memory task in schizophrenia: A fNIRS study

Neurocognitive cognitive deficits including working memory (WM) impairment is a key component of schizophrenia (SCZ). Though a prefrontal cortex (PFC) abnormality is recognised to contribute to WM impairment, the exact nature of its neurobiological basis in SCZ is not well established. Functional near infra-red spectroscopy (fNIRS) is an emerging low-cost neuroimaging tool to study neuro-hemodynamics. In this background, we examined the hemodynamic activity during a WM task in schizophrenia using fNIRS. fNIRS was acquired during computerised N-back (zero-, one- & two-back) task in 15 SCZ patients and compared with 22 healthy controls. Performance in N-back test were calculated using signal detection theory alongside the mean reaction times. Concentration and latencies of oxy-, deoxy-, and totalhaemoglobin, and oxygen saturation were computed from 8*8 optodes positioned over bilateral PFC. SCZ performed poorly as measured by most of the WM parameters (p < 0.05). Lesser deoxyhemoglobin concentration (two > zero, at right BA10, p = 0.006) was noted in the right frontopolar cortex in SCZ surviving multiple-comparison correction. In addition, olanzapine equivalent doses correlated negatively with right frontopolar cortex activation (two > zero back, BA10, ρ = 0.70, p = 0.004) and better performance in two back (false alarm rate, ρ = 0.61, p = 0.015). A delayed but compensatory hyperactivation of right frontopolar cortex noted in SCZ may underlie the WM deficit in SCZ. Future studies are recommended to replicate the role of right frontopolar cortex in WM using larger samples and systematically explore the effect of antipsychotics on them.

Social dysfunction in mood disorders and schizophrenia: Clinical modulators in four independent samples

INTRODUCTION

Social dysfunction is a common symptom of several neuropsychiatric disorders. However, only in the last few years research began to systematically investigate clinical aspects of this relevant outcome. Interestingly, its distribution and link with other clinical variables is still unclear. This study investigated social dysfunction in 4 different cohorts of patients affected by mood disorders and schizophrenia to evaluate 1) the degree of social dysfunction in these populations; 2) the associations among social dysfunction and socio-demographic and psychopathological features.

METHODS

Data from 4 independent studies (CATIE, GSRD ES1, ES2 and ES3, STAR*D, STEP-BD) were investigated. Behavioural and affective indicators of social dysfunction were derived and operationalized from scales or questionnaire items related to the interaction with relatives, friends and significant people in patients affected by schizophrenia (N = 765) and mood disorders (N = 2278 + 1954 + 1829). In particular the social dysfunction indicator was derived from Sheehan Disability Scale (SDS) for GSRD sample, from the Work and Social Adjustment Scale (WSAS) for STAR*D sample, from the Life-Range of Impaired Functioning Tool (LRIFT) for STEP-BD sample, and from the Quality of Life Scale (QOLS) for CATIE sample. The distribution of social dysfunction was described and association with socio-demographic and psychopathological characteristics were analysed.

RESULTS

Social dysfunction indicators showed a broad distribution in all samples investigated. Consistently across studies, social dysfunction was associated with higher psychopathological severity (all samples except CATIE) and suicide risk (GSRD ES1 and ES2, STAR*D, and STEP-BD) that explain up to 47% of the variance, but also to lower education level (GSRD ES2, STAR*D, CATIE, and STEP-BD), poorer professional/work status (GSRD ES2 and ES3, STAR*D, CATIE, and STEP-BD), marital status (STAR*D and CATIE), age (younger age in GSRD ES1 and STAR*D, older age in CATIE), higher BMI (GSRD ES2 and ES3, and STEP-BD), and smoking (GSRD ES2 and ES3).

CONCLUSION

Our results demonstrated that a significant percentage of patients affected by both mood disorders and schizophrenia shows relevant social dysfunction. Social dysfunction is related, but not completely explained by psychopathological severity. In several patients, it tends to persist also during remission state. Socio-demographic and lifestyle factors were also found to play a role and should therefore be taken into consideration in further studies investigating social dysfunction.

Validation of a brain-computer interface version of the digit symbol substitution test in healthy subjects

Digit symbol substitution test (DSST), which is a valid and sensitive tool to assess human cognitive dysfunction, has been widely used in clinical neuropsychology. Although several versions of DSST are currently available, most of the existing DSST versions rely on examinees' intact motor function. This limits their utility in severely motor-impaired individuals. A brain-computer interface (BCI) version of DSST was implemented in this study. Steady-state visual evoked potential (SSVEP) was adopted to build the BCI. Nine symbols in the proposed SSVEP BCI-based DSST were designed with clearly different shapes for decreasing measurement errors due to misidentified symbols. To reduce practice effect, furthermore, the digit-symbol pairs of each trial were different. A two-target SSVEP BCI was designed to judge whether the digit-symbol probe in the center of the user interface matched one of the nine digit-symbol pairs above the user interface. All 12 examinees were able to perform the tasks using the proposed SSVEP BCI-based DSST with 96.17 ± 4.18% averaged accuracy, which was comparable with that of computerized DSST. Furthermore, for examinees participating in both offline and online experiment, the accuracies of the online and offline experiments were comparable, supporting that the proposed BCI-DSST was reliable for repeatedly evaluating examinees' cognitive function over time. These results verified that the proposed SSVEP BCI-based DSST was feasible and effective for healthy subjects.

Assessment of current clinical practices for major depression in Japan using a web-based questionnaire

PURPOSE

To investigate the current clinical practice of Japanese physicians in the diagnosis and management of major depression (major depressive disorder [MDD]).

PATIENTS AND METHODS

Japanese physicians specializing in psychiatry or psychosomatic medicine in the medical database of Nihon Ultmarc Inc. (Chuo-Ku, Tokyo, Japan), who had treated ≥30 patients with MDD in the past month were invited to complete a web-based questionnaire from January 15 to 29, 2018. The questionnaire was comprised of 28 questions pertaining to the physician's background, the criteria and tools used to diagnose MDD during physician-patient consultation, and actual and preferred duration of physician-patient consultation. Responses were given as single answer numerical values or as multiple-choice answers.

RESULTS

From the 518 physicians invited to participate, 340 completed questionnaires were analyzed. Respondents were predominantly male (90%), hospital based (73%), affiliated with the Department of Psychiatry (95%), and members of the Japanese Society of Psychiatry and Neurology (87%). The majority of physicians (84%) agreed that "improvement of cognitive dysfunction caused by major depression is an important factor for patients to return to work" was the most challenging aspect of MDD diagnosis and management. Moreover, 83% of physicians conducted psychological assessments using a cognition evaluation test with most of their patients at the time of MDD diagnosis; the most commonly used tool was the Hasegawa Dementia Scale-Revised. Both hospital-based physicians and general practitioners would prefer to have longer consultations with their patients.

CONCLUSION

Physicians acknowledge the importance of the assessment and management of cognitive dysfunction in patients with MDD. However, most physicians would prefer to have longer consultation times with their patients for the diagnosis of MDD. In the future, it may be useful to introduce digital tools (eg, THINC-it^®) for the initial screening of cognitive dysfunction.