Effect of depression on dementia presentation: qualitative assessment with the Qualitative Evaluation of Dementia (QED).

Two novel, bedside, dementia assessment instruments, the Executive Interview (EXIT) and the Qualitative Evaluation of Dementia (QED) were used to examine the effects of DSM-III-R major depressive episodes on the clinical presentation of patients diagnosed with NINCDS "possible" AD. Intergroup comparisons were made of the various bedside cognitive measures given to 102 of 118 consecutive patients presenting to a university geriatric assessment clinic and consultation service. The assessment instruments used were: (1) the EXIT: a 15-minute, 25-item bedside interview for the assessment of executive control function (ECF); (2) the QED: a brief, clinically based checklist that operationalizes the approach of a geriatric psychiatrist to the qualitative assessment of dementing illnesses (when QED scores are mapped against EXIT scores, a qualitative picture of dementia typology emerges); and (3) the Mini-Mental State Exam (MMSE): a familiar bedside measure of cognitive function. Depressed and nondepressed patients differed significantly on the QED. There was no overlap in the QED scores of patients with probable AD versus those with depression. The QED discriminated between depressed and nondepressed patients with possible AD. Possible AD patients with depression could not be qualitatively distinguished from those with depression alone, although they could be discriminated by the EXIT. Only 44% of possible AD cases fall within the EXIT x QED 90% confidence limits for probable AD. No differences were found on either the QED or the MMSE between depressed non-AD patients and nondepressed patients exhibiting "dementia with no cortical features." The MMSE was insensitive to cognitive impairment in non-AD cases. NINCDS "possible" AD is a qualitatively heterogeneous group.(ABSTRACT TRUNCATED AT 250 WORDS)