Metabolic compensation and depression in Alzheimer's disease.
OBJECTIVE
The aim of this study was to map metabolic compensation and depression in Alzheimer's disease (AD) on a voxel-by-voxel basis.


METHODS
Twenty-one healthy elderly subjects and 25 AD patients underwent cerebral MR and FDG-PET imaging. All images were processed with SPM2, and whole-brain gray matter (GM) atrophy and hypometabolism maps were computed. Metabolic compensation and depression were assessed using Biological Parametric Mapping software.


RESULTS
GM atrophy and hypometabolism mapped to similar regions, with varying degrees of severity. Significant metabolic compensation was found in the amygdala, while exceeding hypometabolism was mainly located in the posterior cingulate cortex.


CONCLUSIONS
Metabolic depression can be due to both distant effects of atrophy and to additional hypometabolism-inducing factors, such as amyloid deposition. Conversely, metabolic compensation could reflect spared synaptic plasticity of the surviving neurons. The investigation of the metabolic compensation mechanism could help in the comprehension of the AD underlying pathology.
Caroli
A
A
LENITEM Laboratory of Epidemiology, Neuroimaging and Telemedicine, IRCCS S. Giovanni di Dio-Fatebenefratelli, Brescia, Italy.
Lorenzi
M
M
Geroldi
C
C
Nobili
F
F
Paghera
B
B
Bonetti
M
M
Cotelli
M
M
Frisoni
G B
GB
D000368:Aged; D000544:Alzheimer Disease / Q000150:complications / Q000378:metabolism* / Q000523:psychology*; D001284:Atrophy; D001921:Brain / Q000473:pathology; D001923:Brain Chemistry; D003863:Depression / Q000209:etiology / Q000378:metabolism* / Q000523:psychology*; D056344:Executive Function / Q000502:physiology; D005260:Female; D019788:Fluorodeoxyglucose F18; D006304:Health Status; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008568:Memory / Q000502:physiology; D008875:Middle Aged; D009483:Neuropsychological Tests; D049268:Positron-Emission Tomography; D011569:Psychiatric Status Rating Scales; D019275:Radiopharmaceuticals
D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18