Hajime Takechi

AIM: Hippocampal atrophy shown on magnetic resonance imaging can differentiate Alzheimer's disease (AD) patients from subjects with normal cognition (NC). Simplified automated methods that use volumetric analysis, such as as the voxel-based specific regional analysis system for AD, have become widely used in Japan. However, the diagnostic value of the voxel-based specific regional analysis system compared with visual rating scores for clinical diagnosis is unclear. METHODS: Study participants consisted of 37 AD patients, 29 mild cognitive impairment (MCI) patients, and 21 NC subjects. All participants underwent neuropsychological testing and magnetic resonance imaging. The imaging was scored visually for regional brain atrophy by two raters based on a newly developed visual rating score. The voxel-based specific regional analysis system for AD scores were calculated with the analysis system's advanced software. We analyzed whether these scores aid in discriminating among AD, MCI, and NC. RESULTS: The AD group had significantly different visual rating scores, regional analysis scores, and all neuropsychological test scores than the NC group. The AD group had significantly different visual rating scores than the MCI group, and a significant difference was observed between the MCI and NC groups on regional analysis scores. Both the visual rating and regional analysis scores showed equivalent correlations with the neuropsychological test scores. CONCLUSIONS: Both the visual rating and regional analysis scores are clinically useful tools for differentiating among AD, MCI, and NC.

The accumulation of amyloid-β protein (Aβ) and tau in the brain is a major pathological change related to Alzheimer's disease. We have continued to develop Extracorporeal Blood Aβ Removal Systems (E-BARS) as a method for enhancing Aβ clearance from the brain. Our previous report revealed that dialyzers effectively remove blood Aβ and evoke large Aβ influxes into the blood, resulting in a decrease in brain Aβ accumulation after initiating hemodialysis, and that patients who underwent hemodialysis had lower brain Aβ accumulation than those who did not. Here, plasma total tau concentrations from 30 patients undergoing hemodialysis were measured using an ultrasensitive immunoassay and compared to those from 11 age-matched controls. Plasma total tau concentrations were higher in patients with renal failure regardless of whether they underwent hemodialysis, suggesting the involvement of the kidneys in tau degradation and excretion. Hemodialyzers effectively removed blood Aβ but not extracorporeal blood tau. The influx of tau into the blood was observed at around the 1 h period during hemodialysis sessions. However, the influx amount of tau was far smaller than that of Aβ. Furthermore, histopathological analysis revealed similar, not significantly less, cerebral cortex phosphorylated tau accumulation between the 17 patients who underwent hemodialysis and the 16 age-matched subjects who did not, although both groups showed sparse accumulation. These findings suggest that hemodialysis may induce both tau and Aβ migration into the blood. However, as a therapeutic strategy for Alzheimer's disease, it may only be effective for removing Aβ from the brain.

Since the start of long term care insurance and the availability of Cholinesterase inhibitor as a prescription drug in Japan, detection and diagnosis of dementia in the early stage of the disease has become an important issue. Neuropsychological screening and imaging tools usually employed for diagnosis are insufficient. The use of diagnostic criteria to designate early stage patients is still controversial. Several disease entities, including mild cognitive impairment (MCI) and age-associated memory impairment (AAMI), are not clearly defined in Japan. To study the prognosis of early stage dementia, it is important to define the diagnostic criteria. Clear identification and diagnosis of early stage dementia is important to support patients and their family members. The early detection of dementia and cognitive decline has other important aspects. One is the implication of disease diagnosis in the community people often hesitate to use the name dementia in the early stage, even when the patients fulfill the criteria for dementia. Another aspect is the longer term follow up of the patients after early detection. For these purposes, it will become more important to emphasize a team approach consisting of medical doctors, nurses, neuropsycologists, clinical psycologists, occupational therapists and sociateam workers. © 2002, The Japan Geriatrics Society. All rights reserved.