Relation between medial temporal atrophy and functional brain activity during memory processing in Alzheimer's disease: a combined MRI and SPECT study

Abstract

Objective: To investigate the relation between atrophy of the hippocampal region and brain functional patterns during episodic memory processing in Alzheimer's disease. Patients and methods: Whole brain structural magnetic resonance imaging (MRI) data and single photon emission computed tomography (SPECT) measures of regional cerebral blood flow (rCBF) were obtained during a verbal recognition memory task in nine subjects with mild Alzheimer's disease and 10 elderly healthy controls. Using the statistical parametric mapping approach, voxel based comparisons were made on the MRI data to identify clusters of significantly reduced grey matter concentrations in the hippocampal region in the Alzheimer patients relative to the controls. The mean grey matter density in the voxel cluster of greatest hippocampal atrophy was extracted for each Alzheimer subject. This measure was used to investigate, on a voxel by voxel basis, the presence of significant correlations between the degree of hippocampal atrophy and the rCBF SPECT measures obtained during the memory task. Results: Direct correlations were detected between the hippocampal grey matter density and rCBF values in voxel clusters located bilaterally in the temporal neocortex, in the left medial temporal region, and in the left posterior cingulate cortex during the memory task in the Alzheimer's disease group (p < 0.001). Conversely, measures of hippocampal atrophy were negatively correlated with rCBF values in voxel clusters located in the frontal lobes, involving the right and left inferior frontal gyri and the insula (p < 0.001). Conclusions: Hippocampal atrophic changes in Alzheimer's disease are associated with reduced functional activity in limbic and associative temporal regions during episodic memory processing, but with increased activity in frontal areas, possibly on a compensatory basis.

Successful Verbal Retrieval in Elderly Subjects Is Related to Concurrent Hippocampal and Posterior Cingulate Activation

“…Our study also supports functional connectivity studies proposing a functional relationship between the hippocampus and the posterior cingulate gyrus. In agreement, Garrido et al [27] observed a correlation of hippocampal grey matter density with memory-related activation in the left posterior cingulate gyrus in subjects with AD. Chetelat et al [9] reported that reductions in retrieval performance correlated with hippocampal atrophy but also with reduced resting metabolism in the posterior cingulate gyrus, indicating a morphological and functional dissociation.…”

Fatores de risco cardiovascular, declínio cognitivo e alterações cerebrais detectadas através de técnicas de neuroimagem

“…No campo dos estudos de neuroimagem funcional, diversos estudos utilizando PET ou SPECT têm demonstrado padrão típico de hipofuncionamento cortical de repouso em pacientes portadores de DA, afetando particularmente áreas temporais e parietais (Matsuda et al, 2002;Garrido et al, 2002). Este padrão de hipometabolismo está diretamente relacionado à intensidade dos déficits de memória e atenção nestes pacientes (Matsuda et al, 2002), e difere dos sinais de hipoatividade multi-focais, de localização variada, que podem surgir em quadros de DMI (Yoshikawa et al, 2003).…”

Association between physical activity and quality of life in the elderly: a systematic review, 2000-2012

“…Many scientific studies involving this age group typically have a greater number of female participants, 18 possibly because i) women have a longer life expectancy (6 years longer on average), ii) women have a higher level of social support, are more likely to seek new sources of support, have a greater ability to form bonds, enjoy affectionate relations, and assemble in a group, and iii) women have lower biological vulnerability, as the rate of lethal diseases is higher among men. 66 This review shows some variability among the studies regarding how PA is measured. Only three studies 31,37,47 used direct measures to assess PA.…”