Remote Memory and Lexical Retrieval in a Case of Frontal Pick's Disease

Abstract

To examine the status of remote memory and lexical retrieval processes in a patient with frontal lobe-type dementia studied serially during an 18-month period. Longitudinal single-case study. University hospital. A 67-year-old man presented to the hospital with progressive frontal lobe dysfunction confirmed by neuropsychological testing and single photon emission-computed tomographic scan. Postmortem brain examination demonstrated focal atrophy of the orbitofrontal region of the frontal lobe and medial temporal structures with abundant Pick's bodies and Pick's cells. Anterograde memory was assessed on a range of free recall and recognition tests using verbal and nonverbal material. Remote memory was assessed by Famous Faces and Famous Events tests and the Crovitz test of remote personal memory. Lexical retrieval was examined using initial-letter and semantic category-based fluency tasks. Initially there was a dissociation between anterograde memory, which was severely impaired, and relatively spared remote memory. Within retrograde memory there was evidence of selective difficulty in retrieving contextually rich and time-specific personal memories and in dating personal and public memories. In contrast, retrieval of names of famous persons and recognition of famous events was relatively normal. As the disease progressed, performance on all remote memory tests worsened, but without a temporally graded pattern. Lexical retrieval was markedly impaired and affected to an equivalent degree performance on initial-letter and category fluency tasks. These findings are interpreted in the context of a general retrieval deficit resulting from the interruption of frontostriatal circuits.