"Where to?" remote memory for spatial relations and landmark identity in former taxi drivers with Alzheimer's disease and encephalitis.
Level 4 - case-series / case-control
Comparative neuropsychological case study with healthy and lesion controls
PubMed 15814004 · doi:10.1162/0898929053279496
What was done
Researchers evaluated remote spatial memory and landmark recognition in a patient with probable Alzheimer's disease (S.B.) who had worked as a downtown Toronto taxi driver for 40 years but had rarely visited the area in the preceding decade. S.B.'s brain atrophy primarily affected the hippocampus and part of the occipitotemporal cortex. His performance was compared with two other retired taxi drivers (one with past encephalitis and one neurologically intact) and eight healthy controls who lived or worked in Toronto at least 10 years earlier. Assessments covered mental navigation, spatial location relations, landmark visual discrimination, world landmark recognition, and famous face recognition.
What was found
The abstract reports no numerical scores or statistical metrics. Qualitatively, S.B. performed at least as well as all comparison participants on tests of remote spatial location and mental navigation between familiar landmarks. In contrast to the comparison groups, S.B. failed to visually distinguish frequently visited landmarks from unfamiliar buildings. This deficit extended to famous world landmarks but spared famous face recognition.
Why it matters
The findings indicate that intact hippocampal function is not essential for navigating familiar environments learned long ago, and demonstrate that extensive occupational expertise does not prevent the development of landmark agnosia.
Limits
The study is centered on a single case (total n=11 including controls), severely limiting generalizability. The abstract provides no quantitative test data or error rates. Neurological damage in the patient was widespread rather than strictly focal, confounding precise anatomical attribution.
Cited by
- contradicts Studies show that London taxi drivers do not get Alzheimer's disease.