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Objective: To determine whether the Alzheimer disease (AD) dementia conversion-related pattern (ADCRP) on [ 18 F]FDG PET can serve as a valid predictor for the development of AD dementia, the individual expression of the ADCRP (subject score) and its prognostic value were examined in patients with mild cognitive impairment (MCI) and biologically defined AD., Methods: A total of 269 patients with available [ 18 F]FDG PET, [ 18 F]AV-45 PET, phosphorylated and total tau in CSF, and neurofilament light chain in plasma were included. Following the AT(N) classification scheme, where AD is defined biologically by in vivo biomarkers of β-amyloid (Aβ) deposition ("A") and pathologic tau ("T"), patients were categorized to the A-T-, A+T-, A+T+ (AD), and A-T+ groups., Results: The mean subject score of the ADCRP was significantly higher in the A+T+ group compared to each of the other group (all p < 0.05) but was similar among the latter (all p > 0.1). Within the A+T+ group, the subject score of ADCRP was a significant predictor of conversion to dementia (hazard ratio, 2.02 per z score increase; p < 0.001), with higher predictive value than of alternative biomarkers of neurodegeneration (total tau and neurofilament light chain). Stratification of A+T+ patients by the subject score of ADCRP yielded well-separated groups of high, medium, and low conversion risks., Conclusions: The ADCRP is a valuable biomarker of neurodegeneration in patients with MCI and biologically defined AD. It shows great potential for stratifying the risk and estimating the time to conversion to dementia in patients with MCI and underlying AD (A+T+)., Classification of Evidence: This study provides Class I evidence that [ 18 F]FDG PET predicts the development of AD dementia in individuals with MCI and underlying AD as defined by the AT(N) framework., (© 2021 American Academy of Neurology.)

Purpose of Review: To give an update on recent biomarker imaging studies using single-photon emission computed tomography (SPECT) and positron emission tomography (PET) on cognitive impairment in Lewy-body diseases (LBD)., Recent Findings: Imaging studies of regional cerebral glucose metabolism with [F]fluorodeoxyglucose(FDG)-PET support the concept that Parkinson's disease (PD) with mild cognitive impairment represents a prodromal stage of PD with dementia (PDD). Furthermore, [F]FDG-PET may be suited for risk stratification for dementia in PD. In line with neuropathological studies, preliminary amyloid-beta (Aβ) PET studies suggest that Aβ acts synergistically with Lewy pathology in LBD, leading to an earlier manifestation of cognitive impairment in dementia with Lewy-bodies compared with PDD and a more rapid cognitive decline in PD patients with concomitant Aβ pathology., Summary: Molecular neuroimaging with SPECT and PET provides unique in-vivo insights into neuropathological and pathophysiological changes underlying cognitive impairment in LBD. Future prospective studies are needed to confirm the prognostic value of [F]FDG-PET and to define the value of amyloid PET and upcoming techniques, such as tau imaging, for diagnosis and prognosis in LBD.

Using functional magnetic resonance imaging during a verbal memory task, we investigated correlations of signal fluctuations within the hippocampus and ipsilateral frontal as well as temporal areas in temporal lobe epilepsy patients. Declarative memory abilities were additionally examined before and after temporal lobe epilepsy surgery. A significant difference exists in functional connectivity between patients whose mnemonic functions deteriorated and those who remained stable or improved. Univariate analyses showed significantly higher preoperative coupling between the hippocampus and Brodmann area 22 for the group that decreased in verbal learning. We suggest greater coupling to reflect higher functional network integrity. Postoperatively reduced learning ability in patients with higher preoperative coupling underlines the importance of hippocampal interaction with cortical areas for successful memory formation.

Gender-related differences in brain activation patterns and their lateralization associated with cognitive functions have been reported in the field of language, emotion, and working memory. Differences have been hypothesized to be due to different cognitive strategies. The aim of the present study was to test whether lateralization of brain activation in the hippocampi during memory processing differs between the sexes. We acquired functional magnetic resonance imaging data from healthy female and male study participants performing a spatial memory task and quantitatively assessed the lateralization of hippocampal activation in each participant. Hippocampal activation was significantly more left lateralized in women, and more right lateralized in men. Correspondingly, women rated their strategy as being more verbal than men did.