Abstract
Impairment in delayed recall has traditionally been considered a
hallmark feature of Alzheimer's disease (AD). However,
vulnerability to semantic interference may reflect early manifestations
of the disorder. In this study, 26 mildly demented AD patients (mild
AD), 53 patients with mild cognitive impairment without dementia (MCI),
and 53 normal community-dwelling elders were first presented 10 common
objects that were recalled over 3 learning trials. Subjects were then
presented 10 new semantically related objects followed by recall for
the original targets. After controlling for the degree of overall
memory impairment, mild AD patients demonstrated greater proactive but
equivalent retroactive interference relative to MCI patients. Normal
elderly subjects exhibited the least amount of proactive and
retroactive interference effects. Recall for targets susceptible to
proactive interference correctly classified 81.3% of MCI patients and
81.3% of normal elderly subjects, outperforming measures of delayed
recall and rate of forgetting. Adding recognition memory scores to the
model enhanced both sensitivity (84.6%) and specificity (88.5%). A
combination of proactive and retroactive interference measures yielded
sensitivity of 84.6% and specificity of 96.2% in differentiating mild
AD patients from normal older adults. Susceptibility to proactive
semantic interference may be an early cognitive feature of MCI and AD
patients presenting for clinical evaluation. (JINS, 2004,
10, 91–100.)
