Neuropsychological deficits associated with route learning in Alzheimer disease, MCI, and normal aging.

BACKGROUND: The background of route learning (RL) abilities in Alzheimer disease (AD), mild cognitive impairment (MCI), and normal aging needs further study. We searched for neuropsychological and demographical predictors of RL impairment.
METHODS: RL was investigated in a clinical study including subjects classified as early AD (n=37), MCI (n=34), and aged normal controls (n=46). An ecological assessment procedure of RL was employed and landmarks learning and navigational abilities were evaluated. The consortium to establish a registry of Alzheimer's disease test battery was used for neuropsychological assessment.
RESULTS: Almost all AD patients, and most subjects with MCI misidentified landmarks and made navigational errors when following the route without assistance. Moreover, a small subgroup of normal controls also had problems with RL. Poor RL performance was best predicted by impairments in memory and executive functions.
CONCLUSIONS: RL impairment is common in early AD and MCI, and is occasionally also found in normal elderly subjects. Its characteristic appearance is a combination of poor landmark recognition and defective directional guidance. Poor RL can be predicted by neuropsychological testing. In MCI and in a subset of normal aged persons, RL impairment may herald incipient dementia.