Prefrontal brain morphology and executive function in healthy and depressed elderly.
OBJECTIVE
Late-life depression is known to correlate independently with decreased brain volumes in anterior cingulate, gyrus rectus and orbitofrontal cortex and with executive dysfunction, but the relationship between morphometry of reduced volume regions and executive dysfunction has not been well defined.


METHODS
Nondepressed and depressed elders completed five executive tests, a standard panel of laboratory tests and magnetic resonance imaging. Images of the prefrontal cortex were manually masked and automatically segmented and regional brain volumes were calculated. Executive scores and error rates were regressed on bilateral white and gray matter volumes of anterior cingulate, gyrus rectus and orbitofrontal.


RESULTS
Gyrus rectus was associated positively with scores on sequencing and nonverbal abstract reasoning, and negatively with two fluency error scores. Four positive interactions indicated that performance of controls was more closely associated with increased volume than that of depressed patients. Anterior cingulate was associated positively with two nonverbal reasoning tasks and with three positive interactions. Orbitofrontal volumes were negatively associated with correct responses and errors on two fluency tasks. One interaction showed controls' performance decreased more than depressed patients with increased volume.


CONCLUSIONS
Individual executive tasks correlate positively with volumes of anterior cingulate and gyrus rectus regions and negatively with orbitofrontal region. The orbitofrontal relationship suggests a loss of inhibitory control with decreased volume because both correct and incorrect answers on fluency tasks increased per unit decrease in volume.
Elderkin-Thompson
Virginia
V
Semel Institute for Neuroscience and Human Behavior, Geriatric Division, UCLA, Los Angeles, CA 90024-1759, USA. velderkin@mednet.ucla.edu
Hellemann
Gerhard
G
Pham
Daniel
D
Kumar
Anand
A
D000368:Aged; D000375:Aging / Q000502:physiology / Q000523:psychology; D001931:Brain Mapping / Q000379:methods / Q000706:statistics & numerical data; D003072:Cognition Disorders / Q000473:pathology*; D003866:Depressive Disorder / Q000473:pathology* / Q000503:physiopathology; D056344:Executive Function; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008570:Memory, Short-Term; D008875:Middle Aged; D015999:Multivariate Analysis; D009483:Neuropsychological Tests; D009929:Organ Size; D017397:Prefrontal Cortex / Q000473:pathology* / Q000503:physiopathology; D011340:Problem Solving; D011569:Psychiatric Status Rating Scales; D014705:Verbal Behavior; D014936:Word Association Tests