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Alzheimer's disease (AD) classically presents with gray matter atrophy, as well as feature significant white matter abnormalities. Previous evidence indicates the overall burden of these pathological changes continues to advance as the disease progresses. The aim of this study was to investigate whether pathological alterations of white matter tracts correlate with the course of AD disease progression. 35 AD patients and 29 normal controls were recruited to the study and administered baseline magnetic resonance diffusion tensor imaging (DTI) acquisition and a cognitive function assessment at the time of initial evaluation. Subjects were re-evaluated with secondary DTI scan and cognitive function assessment at intervals of about 1.5 years on average. For the DTI acquired scans, we calculated diffusion tensor parameters, fractional anisotropy (FA), apparent diffusion coefficient (ADC), radial diffusivity (DR), and axial diffusivity (DA) along with the uncinate fasciculus (UNC), the inferior longitudinal fasciculus (ILF), and the inferior occipitofrontal fasciculus (IOFF). Compared to baseline, a significant mean FA reduction of the bilateral UNC, as well as a significant mean DR increase of the left UNC, was evident in AD patients at follow-up. Compared with normal controls, AD patients exhibited significant diffusion parameter abnormalities in their UNC, ILF, and IOFF. Taken together, these results indicate that progressive pathological white matter alterations can be quantified using the DTI parameters utilized here and may prove to be a useful biological marker for monitoring the pathophysiological course of AD.

It has been reported that tooth loss is associated with Alzheimer's disease (AD) and dementia. The purpose of this study was to investigate the association between tooth loss and mild memory impairment (MMI) among the elderly. We examined 3,061 community residents aged 65 years or older who had a score of 24 or more on the Mini-Mental State Examination. The subjects were divided according to their score for the three-word delayed recall test into control (score: 3 or 2) and MMI (score: 1 or 0) subjects. The subjects underwent a dental examination, an interview to determine their medical history, a self-administered questionnaire (inclusive of higher-level functional capacity, drinking and smoking habits, and frequency of going out), and a 10-m walking test. Fewer remaining teeth, going out once a week or less frequently, and a slow walking speed on a 10-m walking test were found at a significantly higher prevalence in the MMI group (n=101) than in the control group (n=2,960), after adjustment for sex, age, and the level of education. Multiple logistic regression analysis using these items revealed that the odds ratio of 0-10 remaining teeth for MMI was 1.71 (95% CI 1.05-2.78), compared to individuals with 22-32 remaining teeth. A significant increase was also found in a trend test to examine the increasing odds ratios of 22-32, 11-21, and 0-10 remaining teeth. We consider that tooth loss is associated with MMI later in life.

Mild cognitive impairment (MCI) is considered the transitional stage between normal cognition and dementia. The aim of this study was to use tractography based analysis to elucidate alterations in subjects with MCI compared with subjects with early Alzheimer's disease (AD) and controls. Seventeen subjects with early AD, 16 with MCI and 16 controls underwent magnetic resonance diffusion tensor imaging (DTI) and neuropsychological assessment. Diffusion tensor tractographies were computed and fiber-tract maps were generated using "dTV II" DTI software. We measured mean fractional anisotropy (FA) and apparent diffusion coefficient (ADC) values along the uncinate fasciculus (UNC), posterior cingulate fasciculus (PCF) and corticospinal tract (CST). There were statistically significant differences in the FA and ADC values of the UNC and PCF between subjects with early AD and controls. Subjects with MCI exhibited significantly lower FA values on both sides of the PCF relative to controls. However, there were no significant differences between subjects with early AD and MCI for any measurement. Our results suggest that alterations in the PCF precede the onset of dementia.