title: Normal and pathological aging--findings of positron-emission-tomography.
abstract: Normal aging of the brain is predominantly characterized by metabolic changes in the prefrontal cortex. While in middle age there is a trend to hyperfrontality, PET demonstrates in old age a decline of regional cerebral glucose metabolism in frontal areas. In progeric diseases, clinically apparent as premature aging, the metabolic pattern is similar like in normal aging but qualitatively more severe. In patients with the diagnosis of probable Alzheimer's disease (AD) hypometabolism in early dementia is typically present in heteromodal association areas. Hypometabolism then spreads to other cortical and subcortical regions suggesting a characteristic pattern of degeneration that reflects selective vulnerability within limbic-cortical networks. Synaptic plasticity, clinically apparent as cognitive reserve capacity, can be assessed by PET under specific cognitive activation. In AD it is reduced in comparison to age-matched normals and may be influenced by drugs giving trophic support to neurochemical systems.
authors.affiliation: Max-Planck-Institut für neurologische Forschung and Universitätsklinik für Neurologie, Köln, Federal Republic of Germany.
authors.forename: R
authors.initials: R
authors.lastname: Mielke
authors.forename: J
authors.initials: J
authors.lastname: Kessler
authors.forename: B
authors.initials: B
authors.lastname: Szelies
authors.forename: K
authors.initials: K
authors.lastname: Herholz
authors.forename: K
authors.initials: K
authors.lastname: Wienhard
authors.forename: W D
authors.initials: WD
authors.lastname: Heiss
mesh_terms: D000375:Aging / Q000502:physiology*; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000503:physiopathology; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism; D001927:Brain Diseases / Q000000981:diagnostic imaging*; D005947:Glucose / Q000378:metabolism; D006801:Humans; D009223:Myotonic Dystrophy / Q000000981:diagnostic imaging; D009473:Neuronal Plasticity / Q000502:physiology; D012016:Reference Values; D013569:Synapses / Q000502:physiology; D014055:Tomography, Emission-Computed
chemical_list: D005947:Glucose