Combined study of cerebral glucose metabolism and [11C]methionine accumulation in probable Alzheimer's disease using positron emission tomography.
There is a characteristic decrease in glucose metabolism in associative frontal and temporo-parietal cortices of patients suffering from Alzheimer's disease (AD). The decrease in metabolism might result from local neuronal loss or from a decrease of synaptic activity. We measured in vivo [11C]methionine accumulation into proteins with positron emission tomography (PET) to assess cortical tissue loss in AD. Both global regional activity and compartmental analysis were used to express [11C]methionine accumulation into brain tissue. Glucose metabolism was measures with [18F]fluorodeoxyglucose and autoradiographic method. Combined studies were performed in 10 patients with probable AD, compared to age-matched healthy volunteers. There was a significant 45% decrease of temporo-parietal glucose metabolism in patients with AD, and frontal metabolism was lowered in most patients. Temporo-parietal metabolism correlated to dementia severity. [11C]methionine incorporation into temporo-parietal and frontal cortices was not significantly decreased in AD. There was no correlation with clinical symptoms. Data suggest that regional tissue loss, assessed by the decrease of [11C]methionine accumulation, is not sufficient to explain cortical glucose hypometabolism, which reflects, rather, reduced synaptic connectivity.
Salmon
E
E
Cyclotron Research Center, University of Liège, Belgium.
Gregoire
M C
MC
Delfiore
G
G
Lemaire
C
C
Degueldre
C
C
Franck
G
G
Comar
D
D
D000368:Aged; D000544:Alzheimer Disease / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000523:psychology; D001921:Brain / Q000000981:diagnostic imaging* / Q000378:metabolism*; D002250:Carbon Radioisotopes; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006801:Humans; D008297:Male; D008715:Methionine / Q000378:metabolism*; D008875:Middle Aged; D008954:Models, Biological; D011569:Psychiatric Status Rating Scales; D012720:Severity of Illness Index; D014018:Tissue Distribution; D014055:Tomography, Emission-Computed
D002250:Carbon Radioisotopes; D008715:Methionine; D005947:Glucose