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IntroductionMolecular imaging and selective hippocampal subfield atrophy are a focus of recent Alzheimer's disease (AD) research. Here, we investigated correlations between molecular imaging and hippocampal subfields in early AD.MethodsWe investigated 18 patients with early AD and 18 healthy control subjects using 11C-Pittsburgh compound-B (PIB) positron emission tomography (PET) and 18F-THK5351 PET and automatic segmentation of hippocampal subfields with high-resolution T2-weighted magnetic resonance imaging. The PET images were normalized and underwent voxelwise regression analysis with each subregion volumes using SPM12.ResultsAs for 18F-THK5351 PET, the bilateral perirhinal cortex volumes were significantly associated with the ipsilateral or bilateral temporal lobar uptakes, whereas hippocampal subfields showed no correlations. 11C-PIB PET showed relatively broad negative correlation with the right cornu ammonis 3 volumes.DiscussionRegional tau deposition was correlated with extrahippocampal subregional atrophy and not with hippocampal subfields, possibly reflecting different underlying mechanisms of atrophy in early AD. Amyloid might be associated with right cornu ammonis 3 atrophy.

BackgroundNeuropsychiatric symptoms (NPS) have been recognized as risk factors for conversion to dementia in patients with mild cognitive impairment (MCI). Early detection of NPS may allow for possible interventions in such patients. The present study used mild behavioural impairment to explore the role of NPS in a wide range of patients, from those who are cognitively intact to those with dementia.MethodsA total of 234 patients with mild cognitive impairment were followed up for up to 3 years in a Japanese cohort study. Longitudinal data from patients who developed dementia during the study and those who did not were statistically analyzed.ResultsCox regression analysis revealed that only abnormal perception and thought was significant in terms of dementia conversion. Moreover, mixed‐effects models indicated that baseline mild behavioural impairment symptoms did not affect cognitive trajectories such as changes in Mini‐Mental State Examination or Alzheimer's Disease Assessment Scale‐cognitive subscale scores.ConclusionWe conclude that only abnormal perception and thought content were risk factors for dementia and that NPS may not lead to deterioration of cognitive function in patients with mild cognitive impairment.

There have been increasing efforts to investigate the effects of neuromodulation techniques, such as transcranial direct current stimulation (tDCS), on cognitive impairment in dementia and related conditions. In this systematic review and meta-analysis, we assessed the efficacy of multisession anodal tDCS compared with sham stimulation for improving global cognition and specific cognitive domains in both Alzheimer's disease and mild cognitive impairment. Eight articles meeting the criteria for inclusion in the meta-analysis were selected. Five studies used the Mini-Mental State Examination to examine mild cognitive impairment and dementia. In a fixed-effect model, there was a mean difference in the change score of -0.13 points. Three trials for dementia using the Alzheimer's Disease Assessment Scale-Cognition showed a mean difference of -0.53 points. At present, there is a lack of clear evidence concerning the efficacy of multisession anodal tDCS due to the small number of studies and different measures used. This underscores the need for further investigations using larger samples and common outcome measures.