Meta-analysis was used to examine the performance
of depressed and Alzheimer-type dementia (DAT) patients
on standard and experimental clinical tests of cognitive
function. Deficits were found for depression on almost
every psychological test. Relative to nondepressed controls,
the average deficit was 0.63 of a standard deviation, but
the magnitude of the effect varied with the type of test.
DAT patients performed worse than depressed patients, with
an average effect size of 1.21 standard deviations, but
the size of the effect depended on the clinical test. Effect
sizes for the comparison between depressives and controls
were significantly affected by age, treatment setting,
ECT use, severity of depression, and the source of diagnostic
criteria, but not by the type of depression. Effect sizes
in the comparison of depressives to DAT patients were influenced
by age, the severity of depression, and ECT. Depressives
performed proportionately worse than controls on tasks
with pleasant or neutral, compared with unpleasant content,
on speeded compared with nonspeeded tasks, and on vigilance
tasks. However, there were no differences in the magnitude
of effect size for tests using recall compared with recognition,
using categorical compared with noncategorical word lists,
on story compared with word comprehension, and using verbal
compared with visual material. Relative to DAT patients,
depressives performed no better on recall compared to recognition
tasks, or verbal compared to visual material. The findings
of the review are not consistent with the hypothesis that
depression is associated with deficits in effortful processing.
A model of psychological deficit in depression as a deficit
in speed or attention has more promise. (JINS,
1997, 3, 631–651.)
Acupuncture for Depression: A Systematic Review and Meta-Analysis
