Recent research has demonstrated deficits on effortful executive
tasks involving planning in multiple sclerosis (MS) patients.
Given the high prevalence of depression in MS and the commonly
reported link between depression and performance on executive
tasks, planning impairments in MS may be associated with
depression. We compared the performance of depressed and
nondepressed MS patients on a planning task (Tower of
London–TOL) to evaluate this hypothesis. Compared with
nondepressed MS patients, depressed MS patients made significantly
(p < .05) more moves and took more time per trial
on the TOL. A follow-up regression analysis was conducted that
included the TOL and speeded attentional/working memory task
indices found to be associated with depression in MS from the
authors' prior reports. This analysis revealed that 25%
of the variance in depression scores was predicted by the most
sensitive speeded attentional/working memory task. Furthermore,
this variance overlapped completely with variance predicted
by the TOL–time/trial index. The only clearly nonspeeded
task index, TOL–moves per trial, was associated with unique
variance (8%) in predicting MS depression scores. These results
suggest that slowed information processing speed and, secondarily,
deficient nonspeeded central executive skill, may be core to
the cognitive deficits characteristic of depressed MS patients.
(JINS, 2001, 7, 665–674.)