Early Phase Of Alzheimer's Disease Research Articles

Functional brain imaging with single-photon emission computed tomography in the diagnosis of Alzheimer's disease.

High-resolution single-photon emission computed tomography (SPECT) with brain-retained technetium-99m (99mTc)-labeled tracers may be used for 3-dimensional measurements of regional cerebral blood flow (rCBF). This article summarizes important findings in SPECT studies of Alzheimer's disease (AD). There are three distinct potential applications of SPECT in diagnosing AD: (a) as a diagnostic adjunct in patients with mild cognitive or behavioral symptoms, suggesting a possible dementia disorder; (b) as a diagnostic adjunct for demented patients in whom the history, physical examination, and laboratory studies are in agreement with a diagnosis of probable AD; and (c) for determining the relative contributions of degenerative and vascular pathology to the clinical picture in demented patients with mixed disease. A clinical diagnosis of probable AD is associated with focal perfusion deficits as measured by SPECT. Characteristically, hypoperfusion is observed in the frontal and temporoparietal association areas, whereas other brain regions are relatively spared. The changes are present in the early phases of AD. The topography of rCBF deficits displays a marked heterogeneity among patients and correlates with cognitive profiles. In patients with mild cognitive complaints, the presence of focal hypoperfusion on SPECT may increase the accuracy of the diagnosis by confirming the presence of brain disease. In patients with probable AD, the presence of temporoparietal rCBF deficits on SPECT increases the accuracy of the clinical diagnosis, in particular when associated with medial temporal lobe atrophy on cranial X-ray computed tomography (CT). The role of SPECT in diagnosing patients with mixed disease remains to be clarified.

2331 Morphological analysis of the thalamic inputs in the subicular complex and retrosplenial cortex of the rat

There is no consensus about which hippocampal subfields become atrophic earliest in the course of Alzheimer's disease (AD).Thirty AD patients, 41 mild cognitive impairment (MCI) patients, and 38 healthy controls (HCs) underwent cerebral magnetic resonance imaging (with an automated segmentation protocol for the volumetric analysis of hippocampal subfields) and a test of immediate and delayed recall of a 15-word list.The volumes of the presubiculum and subiculum presented the most remarkable reduction in the patient's groups. In the MCI group, only the volumes of presubiculum and subiculum predicted performance on the memory tests. In AD patients, the volumes of all hippocampal subfields (with the notable exception of the CA1) predicted memory scores.Our data point to a prevalent atrophy of the presubicular-subicular complex from the early phases of AD. This finding is consistent with neuropathological observations in AD patients and probably reflects the severe degeneration of the perforant pathway while penetrating the hippocampus through the subicular field in its course from the entorhinal cortex to the dentate gyrus.

2332 Impaired spatial learning by nr2b antisense oligodeoxynucleotide

There is no consensus about which hippocampal subfields become atrophic earliest in the course of Alzheimer's disease (AD).Thirty AD patients, 41 mild cognitive impairment (MCI) patients, and 38 healthy controls (HCs) underwent cerebral magnetic resonance imaging (with an automated segmentation protocol for the volumetric analysis of hippocampal subfields) and a test of immediate and delayed recall of a 15-word list.The volumes of the presubiculum and subiculum presented the most remarkable reduction in the patient's groups. In the MCI group, only the volumes of presubiculum and subiculum predicted performance on the memory tests. In AD patients, the volumes of all hippocampal subfields (with the notable exception of the CA1) predicted memory scores.Our data point to a prevalent atrophy of the presubicular-subicular complex from the early phases of AD. This finding is consistent with neuropathological observations in AD patients and probably reflects the severe degeneration of the perforant pathway while penetrating the hippocampus through the subicular field in its course from the entorhinal cortex to the dentate gyrus.

Correlations between cognitive impairment, middle cerebral artery flow velocity and cortical glucose metabolism in the early phase of Alzheimer's disease.

In a previous transcranial Doppler (TCD) study, we demonstrated a decrease in blood flow velocity in the proximal tract of the middle cerebral artery (MCA) in patients with Alzheimer's disease (AD). In these patients there was also an asymmetry in blood flow velocity which positively correlated with the cognitive asymmetry often seen in the early phase of AD. In this study we found a correlation between the absolute values and asymmetry indexes of MCA blood flow velocity with adjusted metabolic values and asymmetry indexes of the relative cortical frontotemporoparietal (FTP) areas, evaluated by FDG-PET, and with neuropsychological asymmetry indexes. Patients with prevalent visuospatial deficits (right hemisphere dysfunction) showed significant decreases in right MCA blood flow velocity and right FTP cortical glucose hypometabolism, whereas in patients with prevalent language deficits (left hemisphere dysfunction), these signs were observed on the other side. In AD patients, the decrease of blood flow velocity in MCA might be due to reduced metabolic demands in the temporoparietal cortical areas primarily affected by AD.