Hervé Lemaître

Publications (4)17.68 Total impact

• Source

  Available from: Nathalie Tzourio-Mazoyer

  Article: Effects of ApoE-epsilon4 allele load and age on the rates of grey matter and hippocampal volumes loss in a longitudinal cohort of 1186 healthy elderly persons.

  Fabrice Crivello, Hervé Lemaître, Carole Dufouil, Blandine Grassiot, Nicolas Delcroix, Nathalie Tzourio-Mazoyer, Christophe Tzourio, Bernard Mazoyer
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  ABSTRACT: In a sample of 1186 healthy subjects aged 65 to 89 years who were scanned twice with MRI 3.6 years apart, we studied the effects of age and ApoE-epsilon4 allele load on the rate of atrophy of grey matter and hippocampus. Rates of grey matter and hippocampal volumes loss were computed from T1-weighted magnetic resonance images using voxel-based morphometry and region of interest analysis. Longitudinal analysis showed that an age-related annual rate of grey matter volume loss was only seen in epsilon4 homozygotes only (n=14) whereas no age effect was seen epsilon4 heterozygotes (n=239) and in noncarriers (n=933). ApoE-epsilon4 homozygotes also had a significantly larger rate of hippocampal volume loss than heterozygotes or noncarriers. During the same period, no effect or interaction of ApoE genotype and age was observed on cognitive decline, as assessed by the Mini Mental State Examination (MMSE). These data do not suggest an epsilon4 gene dose effect on the rate of hippocampal volume loss in healthy elderly subjects as most of the effect was limited to homozygotes. Hippocampal volume loss may not be a good imaging marker to understand the effect of the ApoE-epsilon4 allele on the risk of dementia in a population-based setting. It could be hypothesized that the impact of a single ApoE-epsilon4 allele on brain structures is largely delayed in time.
  NeuroImage 11/2010; 53(3):1064-9. · 5.89 Impact Factor
• Source

  Available from: Fabrice Crivello

  Article: Age- and sex-related effects on the neuroanatomy of healthy elderly.

  Hervé Lemaître, Fabrice Crivello, Blandine Grassiot, Annick Alpérovitch, Christophe Tzourio, Bernard Mazoyer
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  ABSTRACT: Effects of age and sex, and their interaction on the structural brain anatomy of healthy elderly were assessed thanks to a cross-sectional study of a cohort of 662 subjects aged from 63 to 75 years. T1- and T2-weighted MRI scans were acquired in each subject and further processed using a voxel-based approach that was optimized for the identification of the cerebrospinal fluid (CSF) compartment. Analysis of covariance revealed a classical neuroanatomy sexual dimorphism, men exhibiting larger gray matter (GM), white matter (WM), and CSF compartment volumes, together with larger WM and CSF fractions, whereas women showed larger GM fraction. GM and WM were found to significantly decrease with age, while CSF volume significantly increased. Tissue probability map analysis showed that the highest rates of GM atrophy in this age range were localized in primary cortices, the angular and superior parietal gyri, the orbital part of the prefrontal cortex, and in the hippocampal region. There was no significant interaction between "Sex" and "Age" for any of the tissue volumes, as well as for any of the tissue probability maps. These findings indicate that brain atrophy during the seventh and eighth decades of life is ubiquitous and proceeds at a rate that is not modulated by "Sex".
  NeuroImage 08/2005; 26(3):900-11. · 5.89 Impact Factor
• Source

  Available from: Fabrice Crivello

  Article: No epsilon4 gene dose effect on hippocampal atrophy in a large MRI database of healthy elderly subjects.

  Hervé Lemaître, Fabrice Crivello, Carole Dufouil, Blandine Grassiot, Christophe Tzourio, Annick Alpérovitch, Bernard Mazoyer
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  ABSTRACT: The effect of ApoE genotype on grey matter (GM) atrophy was studied on a cohort of 750 healthy elderly volunteers (age range 63-75 years). High-resolution T1-weighted MR images were processed using both voxel-based morphometry and region of interest analysis for hippocampal volume estimation. Significant decrease of grey matter in epsilon(4) homozygous subjects (n = 12), as compared both to epsilon(4) heterozygous subjects (n = 175) and to noncarrier (n = 563) subjects, was found bilaterally in the medial temporal lobe, including the hippocampus, and extending over the superior temporal gyrus. By contrast, no significant difference was observed between epsilon(4) heterozygous subjects and noncarriers at the level of the medial temporal lobe. Follow-up of the cohort cognitive performances over 4 years after their MRI exam revealed that, as compared to noncarrier subjects, the relative risk of cognitive impairment was 5.9 for epsilon(4) homozygous subjects (P = 0.03), while it was not different from 1 for epsilon(4) heterozygous subjects (P = 0.92). These findings indicate that, in the age range of this cohort, ApoE-4 effects on cortical atrophy and cognitive performances of healthy elderly are limited to epsilon(4) homozygous subjects.
  NeuroImage 03/2005; 24(4):1205-13. · 5.89 Impact Factor
• Article: No ɛ4 gene dose effect on hippocampal atrophy in a large MRI database of healthy elderly subjects

  Hervé Lemaître, Fabrice Crivello, Carole Dufouil, Blandine Grassiot, Christophe Tzourio, Annick Alpérovitch, Bernard Mazoyer
  [show abstract] [hide abstract]
  ABSTRACT: The effect of ApoE genotype on grey matter (GM) atrophy was studied on a cohort of 750 healthy elderly volunteers (age range 63–75 years). High-resolution T1-weighted MR images were processed using both voxel-based morphometry and region of interest analysis for hippocampal volume estimation. Significant decrease of grey matter in ɛ4 homozygous subjects (n = 12), as compared both to ɛ4 heterozygous subjects (n = 175) and to noncarrier (n = 563) subjects, was found bilaterally in the medial temporal lobe, including the hippocampus, and extending over the superior temporal gyrus. By contrast, no significant difference was observed between ɛ4 heterozygous subjects and noncarriers at the level of the medial temporal lobe. Follow-up of the cohort cognitive performances over 4 years after their MRI exam revealed that, as compared to noncarrier subjects, the relative risk of cognitive impairment was 5.9 for ɛ4 homozygous subjects (P = 0.03), while it was not different from 1 for ɛ4 heterozygous subjects (P = 0.92). These findings indicate that, in the age range of this cohort, ApoE-4 effects on cortical atrophy and cognitive performances of healthy elderly are limited to ɛ4 homozygous subjects.
  NeuroImage.