To the Editor.—
In the article, "Reversible Dementia: Illustrative Cases, Definition, and Review," by Cummings et al (1980;243:2434), the authors present a commendable review of many illnesses that could masquerade as primary dementia. They gave an extensive list of conditions that should be considered in the differential diagnosis, including some rather unusual and rare conditions. However, no mention is made about pseudodementia—a mimicry of dementia by functional psychiatric illnesses.1,2This condition is not at all an unusual phenomenon in the aged. When cognitive dysfunction has been relatively abrupt in its onset, is of short duration, and has some obvious temporal relationship to a major emotional upheaval, a diagnosis of pseudodementia should be suspected. Subjective exaggeration of cognitive defects, many "near misses," and "I do not know" answers are typical of these patients. Substantial variability in performance with perhaps excellent performance on difficult tasks but total failure on simple tasks