Cognitive function in late life depression: relationships to depression severity, cerebrovascular risk factors and processing speed.
BACKGROUND
A number of studies have examined clinical factors linked to worse neuropsychological performance in late life depression (LLD). To understand the influence of LLD on cognition, it is important to determine if deficits in a number of cognitive domains are relatively independent, or mediated by depression- related deficits in a basic domain such as processing speed.


METHODS
Patients who met DSM-IV criteria for major depression (n = 155) were administered a comprehensive neuropsychological battery of tasks grouped into episodic memory, language, working memory, executive function, and processing speed domains. Multiple regression analyses were conducted to determine contributions of predictor variables to cognitive domains.


RESULTS
Age, depression severity, education, race and vascular risk factors all made significant and independent contributions to one or more domains of cognitive function, with all five making independent contributions to processing speed. Age of onset made no independent contribution, after accounting for age and vascular risk factors. Of the five cognitive domains investigated, changes in processing speed were found to most fully mediate the influence of predictor variables on all other cognitive domains.


CONCLUSIONS
While slowed processing speed appears to be the most core cognitive deficit in LLD, it was closely followed by executive function as a core cognitive deficit. Future research is needed to help clarify mechanisms leading to LLD- related changes in processing speed, including the potential role of white matter abnormalities.
Sheline
Yvette I
YI
Department of Psychiatry, Washington University, St. Louis, Missouri, USA. yvette@npg.wustl.edu
Barch
Deanna M
DM
Garcia
Keith
K
Gersing
Kenneth
K
Pieper
Carl
C
Welsh-Bohmer
Kathleen
K
Steffens
David C
DC
Doraiswamy
P Murali
PM
D000203:Activities of Daily Living; D000367:Age Factors; D000368:Aged; D016022:Case-Control Studies; D002561:Cerebrovascular Disorders / Q000503:physiopathology*; D003071:Cognition / Q000502:physiology*; D003863:Depression / Q000503:physiopathology* / Q000523:psychology; D004522:Educational Status; D005260:Female; D006801:Humans; D007858:Learning / Q000502:physiology; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011340:Problem Solving / Q000502:physiology*; D011569:Psychiatric Status Rating Scales / Q000706:statistics & numerical data; D012044:Regression Analysis; D012307:Risk Factors