Delusional thoughts and regional frontal/temporal cortex metabolism in Alzheimer's disease.
OBJECTIVE
Delusional thoughts are common in patients with Alzheimer's disease and contribute prominently to morbidity. The pathophysiologic underpinnings for delusions in Alzheimer's disease are not well understood. In this study the authors examined the relationship between delusional thoughts and regional cortical metabolism in patients with Alzheimer's disease.


METHODS
Twenty-five patients with probable Alzheimer's disease were included. None was taking psychotropic medication. Severity of delusions and other neuropsychiatric symptoms was assessed by using a semistructured interview and the Neurobehavioral Rating Scale just before the imaging procedure. [(18)F]Fluorodeoxyglucose positron emission tomography was used to measure resting cerebral glucose metabolic rates in the cortical lobes and in anatomically defined subregions of the frontal and temporal cortexes.


RESULTS
A linear regression model, controlling for the effects of cognitive deficits, revealed a significant relationship between severity of delusional thought and the metabolic rates in three frontal regions: the right superior dorsolateral frontal cortex (Brodmann's area 8), the right inferior frontal pole (Brodmann's area 10), and the right lateral orbitofrontal region (Brodmann's area 47). Bivariate partial correlation analysis indicated that severity of delusions was associated with hypometabolism in additional prefrontal and anterior cingulate regions. Robust relationships with metabolism in regions of the temporal cortex were not apparent.


CONCLUSIONS
Dysmetabolism in specific regions of the right prefrontal cortex may be associated with delusional thought in Alzheimer's disease. Delusions appear to reflect the pathophysiologic state of particular cortical regions. Activity across distributed neuronal networks and the specific content of delusional thoughts may modulate these relationships.
Sultzer
David L
DL
Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, USA. dsultzer@ucla.edu
Brown
Charles V
CV
Mandelkern
Mark A
MA
Mahler
Michael E
ME
Mendez
Mario F
MF
Chen
Stephen T
ST
Cummings
Jeffrey L
JL
D000368:Aged; D000544:Alzheimer Disease / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D003072:Cognition Disorders / Q000175:diagnosis / Q000503:physiopathology / Q000523:psychology; D003702:Delusions / Q000175:diagnosis* / Q000378:metabolism / Q000503:physiopathology; D005260:Female; D019788:Fluorodeoxyglucose F18; D005625:Frontal Lobe / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D007839:Functional Laterality / Q000502:physiology; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D012044:Regression Analysis; D012720:Severity of Illness Index; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000378:metabolism* / Q000503:physiopathology; D014055:Tomography, Emission-Computed
D019788:Fluorodeoxyglucose F18