DTI and MR Volumetry of Hippocampus-PC/PCC Circuit: In Search of Early Micro- and Macrostructural Signs of Alzheimers's Disease

Hippocampal damage, by DTI or MR volumetry, and PET hypoperfusion of precuneus/posterior cingulate cortex (PC/PCC) were proposed as biomarkers of conversion from preclinical (MCI) to clinical stage of Alzheimer's disease (AD). This study evaluated structural damage, by DTI and MR volumetry, of hippocampi and tracts connecting hippocampus to PC/PCC (hipp-PC/PCC) in 10 AD, 10 MCI, and 18 healthy controls (CTRL). Normalized volumes, mean diffusivity (MD), and fractional anisotropy (FA) were obtained for grey matter (GM), white matter (WM), hippocampi, PC/PCC, and hipp-PC/PCC tracts. In hippocampi and hipp-PC/PCC tracts, decreased volumes and increased MD were found in AD versus CTRL (P<.001). The same results with lower significance (P<.05) were found in MCI versus CTRL. Verbal memory correlated (P<.05) in AD with left hippocampal and hipp-PC/PCC tract MD, and in MCI with FA of total WM. Both DTI and MR volumetry of hippocampi and hipp-PC/PCC tracts detect early signs of AD in MCI patients.

Comparative study of the effects of intranasal insulin on memory deficits in type 2 diabetes and early Alzheimer's dementia concept and study scope

IntroductionRecent data support the view that the neurodegeneration underlying sporadic Alzheimer's Disease (AD) is in part related to brain insulin deficiency and brain insulin resistance. There is a higher incidence of AD in patients with diabetes mellitus type II (T2D) and both diseases show a decline in memory function. In a preceding trial intranasal insulin improved memory function in healthy volunteers so that an increase of central-nervous insulin concentration may improve cognitive function in both amnestic patient groups.AimsWe want to analyse the effects of intranasal insulin on patients with early Alzheimers's disease (eAD) and patients with T2D in the state of amnestic mild cognitive impairment (aMCI).MethodsRecruitment of 30 patients with eAD, 30 patients with T2D in aMCI state and 30 age-matched healthy controls. All patients undergo a run-in period of 2 weeks with 4 × daily administration of placebo. It follows a double blinded trial with daily intranasal administration of 4 × 40 I.U. insulin vs. placebo for 8 weeks and another 8 weeks of follow-up. At 4 defined time points memory function is assessed by word lists comprising 30 items of emotional, nutritional and neutral content which have to be memorized and are recalled after one week. To assess structural changes of the brain, a quantitative analysis for hippocampal N-acetyl-aspartate, choline and creatine is performed by 3 Tesla magnetic resonance spectroscopy.Results: Since the study has not finished yet, we present experiences from the initiation and the beginning phase.

Neuron Loss in Transgenic Mouse Models of Alzheimer's Disease

Since their initial generation in the mid 1990s, transgenic mouse models of Alzheimers's disease (AD) have been proven to be valuable model systems which are indispensable for modern AD research. Whereas most of these models are characterized by extensive amyloid plaque pathology, inflammatory changes and often behavioral deficits, modeling of neuron loss was much less successful. The present paper discusses the current achievements of modeling neuron loss in transgenic mouse models based on APP/Aβand Tau overexpression and provides an overview of currently available AD mouse models showing these pathological alterations.