Prevalence of dementia and dementing diseases in Japan: the Tajiri project.

BACKGROUND: Vascular dementia (VaD) has been considered to be more prevalent than Alzheimer disease in Japan. However, this might be the result of overdiagnosis stemming from some problematic diagnosis of VaD or of the frequent use of magnetic resonance imaging to detect cerebrovascular disease in older adults. OBJECTIVES: We investigated the prevalence of dementia and the ratios of dementing diseases. The effects of different criteria for VaD (DSM-IV, Alzheimer's Disease Diagnostic and Treatment Centers [ADDTC], and National Institute of Neurological Disorders and Stroke and the Association Internationale pour la Recherche et l'Enseignement en Neurosciences [NINDS-AIREN]) were considered. Hippocampal atrophy and vascular contribution to dementia were evaluated using magnetic resonance imaging findings. METHODS: We targeted all residents 65 years and older (n = 3207) in Tajiri, Japan, and examined 1654 (participant group 1). Of these, 564 (participant group 2) were randomly selected, and 497 underwent magnetic resonance imaging and diagnosis of dementing diseases. RESULTS: We found the overall prevalence of dementia to be 8.5% (141/1654) in participant group 1. Of these, 21 (14.9%) had a history of stroke. Of the 113 participants who had a history of stroke independent of dementia, 18.6% (21/113) were demented. For participant group 2 (n = 497), 32 were demented. The ratio among the dementia for probable VaD based on the NINDS-AIREN criteria was 18.8% (6/32), whereas that for ischemic vascular dementia was 31.3% (10/32) according to the ADDTC criteria. CONCLUSION: We confirmed the overall prevalence of dementia in adults 65 years and older to be 8.5%. We found that VaD was not a common disorder according to the NINDS-AIREN criteria. Rather, the condition of possible Alzheimer disease with cerebrovascular disease was more common.

Neuropsychosocial features of very mild Alzheimer's disease (CDR 0.5) and progression to dementia in a community: the Tajiri project.

The borderline condition between normal aging and dementia should be detected to predict further deterioration. The authors cross-sectionally analyzed neuropsychological data, memory complaints, and social activities for community-dwelling older adults. The rate of decline from Clinical Dementia Rating (CDR) 0.5 to dementia during a 3-year interval was also analyzed. Short-term memory rather than long-term memory was found to be sensitive in distinguishing those with CDR 0 from those with CDR 0.5. Relatives' observations of memory decline rather than subjective memory complaints were significantly different. Participants with CDR 0.5 reported fewer problems with social activities than did their relatives. Ten of the 29 CDR 0.5 participants (34.5%) showed cognitive decline, the decliners showing lower scores on short-term memory and orientation at the baseline condition. The neuropsychological data showed CDR 0.5 to be similar to very mild Alzheimer's disease. It would be better if subjective complaints were excluded from the criteria of the borderline condition.

Executive dysfunction can explain word-list learning disability in very mild Alzheimer's disease: the Tajiri project.

Elderly people with questionable dementia (i.e. a Clinical Dementia Rating (CDR) of 0.5) have been focused on as representing the borderline zone condition between healthy people and dementia patients. Many of them are known to have pathologic traits of very mild Alzheimer's disease (AD). Although they present mild memory disorder, the underlying mechanism has not been fully investigated. Herein is reported the mechanism of learning disability in very mild AD. Eighty-six CDR 0.5 participants and 101 age- and education-matched healthy controls (CDR 0) were randomly selected from a community in the town of Tajiri, Miyagi Prefecture. The word-recall task of the Alzheimer Disease Assessment Scale-Japanese (i.e. learning and recall of 10 words) was administered. The numbers of words recalled in each trial and those never recalled throughout the trials were compared for the two CDR groups. The serial-position function was depicted for three parts (i.e. primary, middle, and recency). The CDR 0.5 group recalled significantly fewer words than the CDR 0 group. The number of never-recalled words was greater in the CDR 0.5 group. A remarkable difference was found in the middle part of the word list. The number of never-recalled words of the CDR 0.5 group was greater in the middle part. The large number of never-recalled words accounted for the poor learning performance of very mild AD participants. The results suggested that very mild AD participants have difficulty in learning and retaining words in the middle part of the word-list because of a functional decline of the central executive system.

Therapeutic psychosocial intervention for elderly subjects with very mild Alzheimer disease in a community: the tajiri project.

Elderly subjects with mild memory impairment but not apparent dementia are the focus of early intervention trials. To examine the effects of structural psychosocial intervention for elderly subjects with very mild Alzheimer disease, i.e., Clinical Dementia Rating 0.5. The design is a prospective study. The experimental group (14 Clinical Dementia Rating 0.5 subjects) and the control group (11 Clinical Dementia Rating 0.5 subjects) were studied. Subjects with cerebrovascular disease as shown by magnetic resonance imaging were excluded. The experimental group participated in activities in a day-care-like setting once a week over a period of 6 months, whereas the control group did not. Each group was reevaluated after approximately 9 months. The effects of intervention were evaluated by cognitive tests, affective scales, a global clinical measure, an observation scale in the sessions, and a projective test. The experimental group showed a significant improvement on the word fluency test, whereas the control group showed a significant decline on the Mini-Mental State Examination, the digit span, and the Trail Making-A test. The experimental group revealed significantly higher levels on the Mini-Mental State Examination and the digit span compared with the control group after the 6-month intervention. A significant improvement was found for the global clinical measure, the observation scale, and the projective test in the experimental group after the intervention. After controlling the potential confounders (age, educational level, baseline cognitive, and affective status) in a multiple regression analysis, the same results were found. We considered that psychosocial intervention had beneficial effects for subjects with very mild Alzheimer disease.

Corpus callosum atrophy, white matter lesions, and frontal executive dysfunction in normal aging and Alzheimer's disease. A community-based study: the Tajiri Project.

BACKGROUND AND OBJECTIVES: Cerebral MRIs of normal aging and Alzheimer's disease (AD) frequently reveal corpus callosum (CC) atrophy, white matter hyperintensity (WMH), and hippocampal atrophy. However, their relationship or the relationship between these findings and cognitive function has not been fully studied. We investigated the relationship between CC atrophy, WMH, and hippocampal atrophy, together with frontal executive dysfunction in both normal aging and AD. METHOD: We examined 170 randomly selected residents from a designated community: 99 Clinical Dementia Rating (CDR) 0 (healthy, control group, HC) participants, 54 CDR 0.5 (very mild AD) patients, and 17 CDR 1 & 2 (probable AD) patients. By means of MRI, WMH and CC atrophy were visually rated. Four portions of the CC and the hippocampal width were measured. A Mini-Mental State Examination and Cognitive Abilities Screening Instrument (CASI) were performed to assess global function. For the frontal function, the CASI subitems of attention and word fluency, letter-based fluency, the Digit Symbol test of the WAIS-R, and Trail Making Tests were performed. RESULTS: Those patients with CDR 1 & 2 had both hippocampal and CC atrophy, whereas the CDR 0.5 patients had only hippocampal atrophy. Frontal executive dysfunction was associated with CC atrophy in both the HC and AD groups. Significant Spearman correlations were noted between CC atrophy and WMH in both groups. The combined effect of CC atrophy and WMH was noted only in the verbal fluency test in the HC group. CONCLUSION: In both groups, CC atrophy was associated with frontal executive dysfunction. The combined effect of CC atrophy and WMH in normal aging was probably due to subclinical ischemic conditions.

Prevalence and cognitive performances of clinical dementia rating 0.5 and mild cognitive impairment in Japan. The Tajiri project.

The borderline zone condition between normal aging and dementia is a major issue of concern. Although the term mild cognitive impairment (MCI) is popular, its prevalence and neuropsychological features have not been fully investigated. We investigated the prevalence and neuropsychological features for Clinical Dementia Rating (CDR) 0.5 and MCI. For normal aging, the effects of age and educational level on cognitive performance were examined. We examined 1501 older residents (46.8%) in Tajiri 65 years of age and older. They performed the Cognitive Abilities Screening Instrument (CASI). Depressive scores and subjective memory complaints were also evaluated. There was no age effect but an educational effect on cognitive performance in healthy adults. We found the overall prevalence of CDR 0.5 to be 30.2%, whereas that of MCI was only 4.9%. All CASI domains were deteriorated except for long-term memory and visual construction in the CDR 0.5 participants compared with healthy adults, suggesting that CDR 0.5 is similar to very mild Alzheimer disease. Memory complaints' data suggested that it would be better to exclude memory complaints from the MCI criteria. We considered that the concept of CDR 0.5 would be more applicable to community residents rather than that of the MCI.