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Introduction: It is critical to develop accurate and universally available biomarkers for dementia diseases to appropriately deal with the dementia problems under world-wide rapid increasing of patients with dementia. In this sense, electroencephalography (EEG) has been utilized as a promising examination to screen and assist in diagnosing dementia, with advantages of sensitiveness to neural functions, inexpensiveness, and high availability. Moreover, the algorithm-based deep learning can expand EEG applicability, yielding accurate and automatic classification easily applied even in general hospitals without any research specialist. Methods: We utilized a novel deep neural network, with which high accuracy of discrimination was archived in neurological disorders in the previous study. Based on this network, we analyzed EEG data of healthy volunteers (HVs, N = 55), patients with Alzheimer’s disease (AD, N = 101), dementia with Lewy bodies (DLB, N = 75), and idiopathic normal pressure hydrocephalus (iNPH, N = 60) to evaluate the discriminative accuracy of these diseases. Results: High discriminative accuracies were archived between HV and patients with dementia, yielding 81.7% (vs. AD), 93.9% (vs. DLB), 93.1% (vs. iNPH), and 87.7% (vs. AD, DLB, and iNPH). Conclusion: This study revealed that the EEG data of patients with dementia were successfully discriminated from HVs based on a novel deep learning algorithm, which could be useful for automatic screening and assisting diagnosis of dementia diseases.

Background: Dementia with Lewy bodies (DLB) is characterized by progressive cognitive decline, fluctuating cognition, visual hallucinations, rapid eye movement sleep behavior disorder, and parkinsonism. DLB is the second most common type of degenerative dementia of all dementia cases. However, DLB, particularly in the early stage, is underdiagnosed and sometimes misdiagnosed with other types of dementia. Thus, it is of great interest investigating neurophysiological markers of DLB. Method: We introduced exact low-resolution brain electromagnetic tomography (eLORETA)-independent component analysis (ICA) to assess activities of 5 electroencephalography (EEG) resting-state networks (RSNs) in 41 drug-free DLB patients. Results: Compared to 80 healthy controls, DLB patients had significantly decreased activities in occipital visual and sensorimotor networks, where DLB patients and healthy controls showed no age dependences in all EEG-RSN activities. Also, we found correlations between all EEG-RSN activities and DLB symptoms. Specifically, decreased occipital α activity showed correlations with worse brain functions related to attention/concentration, visuospatial discrimination, and global cognition. Enhanced visual perception network activity correlated with milder levels of depression and anxiety. Enhanced self-referential network activity correlated with milder levels of depression. Enhanced memory perception network activity correlated with better semantic memory, visuospatial discrimination function, and global cognitive function as well as with severer visual hallucination. In addition, decreased sensorimotor network activity correlated with a better semantic memory. Conclusion: These results indicate that eLORETA-ICA can detect EEG-RSN activity alterations in DLB related to symptoms. Therefore, eLORETA-ICA with EEG data can be a useful noninvasive tool for sensitive detection of EEG-RSN activity changes characteristic of DLB and for understanding the neurophysiological mechanisms underlying this disease.

Objective: To investigate the gustatory function in patients with semantic dementia (SD). Methods: Detection and recognition thresholds of the 4 basic tastes (sweet, salty, sour, and bitter), taste discrimination, and taste identification were evaluated in 18 patients with SD, 18 patients with Alzheimer disease (AD), and 22 healthy controls. Results: Total detection and recognition threshold values were significantly higher in the SD and AD groups than in the control group. Patients with early-stage SD (Clinical Dementia Rating Scale score 0.5) exhibited significantly higher detection and recognition thresholds relative to controls, while increases in recognition threshold were only noted in patients with AD. Patients with SD exhibited significantly higher thresholds for the detection of sweet and salty tastes and the recognition of salty, sour, and bitter tastes, while patients with AD exhibited significantly higher thresholds only for the recognition of salty and sour tastes. Taste discrimination was preserved, whereas taste identification was disturbed, in both the SD and AD groups. Conclusions: Gustatory dysfunction at both the sensory and semantic levels may be among the early symptoms of SD. Although patients with SD had difficulty detecting sweet tastes, they more easily recognized these tastes than others, which may explain their strong preference for sweets.

Background/Aims: Patients with idiopathic normal pressure hydrocephalus (iNPH) are often given shunt operations to reduce the triad symptoms (cognitive impairment, gait disturbance and urinary disturbance). We examined whether they also reduce caregiver burden. Methods: The personal strain (PS) and role strain (RS) factors, which are related to the stress and constraints, respectively, on the caregivers of 81 iNPH patients were evaluated with the Zarit burden interview (ZBI) and each of the triad symptoms was evaluated with the iNPH grading scale (iNPHGS) before and 1 year after the shunt operation. Results: Each of the iNPHGS scores, the total ZBI score and PS factor significantly improved after the shunt operation, but the RS factor did not. The improvement of cognitive impairment was the major factor in reducing caregiver burden. Conclusion: Shunt operations reduced the caregiver burden of iNPH patients.

Background/Aims: A single-nucleotide polymorphism (SNP) in the KIBRA gene, rs17070145, was reported to be significantly associated with episodic memory in cognitively normal cohorts. This observation has expanded genetic studies on KIBRA to Alzheimer’s disease (AD). Importantly, the association between KIBRA and episodic memory in AD has never been addressed. In this study, we investigated whether the KIBRA rs17070145 SNP influences AD episodic memory and the disease in a Japanese cohort. Methods: Blood samples from 346 AD patients and 375 normal cognitive controls were collected and genotyped for rs17070145. Episodic memory was measured in 32 AD patients, diagnosed for the first time, by use of the Rivermead Behavioral Memory Test (RBMT). Results: We found that KIBRA C allele carriers scored significantly lower than KIBRA non-C carriers on both RBMT total profile score (p = 0.042, effect size = 0.84) and RBMT total screening score (p < 0.001, effect size = 1.42). The KIBRA gene did not show association with AD in our Japanese cohort. Conclusion: Our results evidence a strong association between the KIBRA gene and episodic memory impairment in AD, but show no influence on AD in our Japanese cohort. We propose that KIBRA might have an effect similar to cognitive reserve.

Background/Aims: We developed an idiopathic normal-pressure hydrocephalus grading scale (iNPHGS) to classify a triad of disorders (cognitive impairment, gait disturbance and urinary disturbance) of iNPH with a wide range of severity. The purpose of this study was to assess the reliability and validity of this scale in 38 patients with iNPH. Results: The interrater reliability of this scale was high. The iNPHGS cognitive domain score significantly correlated with the cognitive test scores, including the Mini-Mental State Examination (MMSE), the gait domain score with the Up and Go Test and Gait Status Scale scores, and the urinary domain score with the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF) score. The MMSE, Gait Status Scale and ICIQ-SF scores significantly improved in patients whose iNPHGS scores improved after CSF tapping but not in those whose iNPHGS scores did not improve after CSF tapping. Fourteen of the 38 patients received shunt operations. In these 14 patients, changes in the iNPHGS cognitive and urinary domains after CSF tapping were significantly associated with the changes after the shunt operation.

We compared the scores of the Frontal Assessment Battery (FAB), initial fluency subtest, category fluency subtest and subtests of the Mini-Mental State Examination (MMSE) between patients with idiopathic normal pressure hydrocephalus (iNPH) and age-, sex- and MMSE-matched patients with Alzheimer’s disease (AD). In patients with iNPH, the time and number of steps required to go and come back a 10-meter distance were measured (Walking test) and the associations between the scores of the cognitive tests and the performance of the Walking test were evaluated. The scores of the FAB and initial fluency subtest in patients with iNPH were significantly lower than those in patients with AD. The scores of the FAB, initial fluency subtest and serial 7 subtest of the MMSE significantly correlated with the two scores of the Walking test in patients with iNPH. The present results indicate that frontal lobe functions were impaired in patients with iNPH and that cognitive impairment was closely associated with gait disturbance in patients with iNPH.

We evaluated remote autobiographical memory impairment in 25 patients with probable Alzheimer’s disease (AD) and 25 sex-, age- and education-matched healthy subjects by using a newly developed, highly effective assessment tool for remote memory, the Family Line Test (FLT). The FLT yields a total score, scores for 3 lifetime periods and the duration of remote memory impairment. In the patients with AD, the total score was significantly lower and the duration of remote memory impairment was significantly longer than in the healthy controls. A prominent temporal gradient in remote memory impairment was documented in the patients with AD. The total FLT score and duration of remote memory impairment correlated with recent memory and general cognitive dysfunctions.