Functional MR imaging in Alzheimer's disease during memory encoding

BACKGROUND AND PURPOSE: We applied functional MR imaging with a learning ta sk in healthy elderly volunteers and in patients with Alzheimer's disease t o study brain activation during memory performance. The purpose was to dete rmine the feasibility of functional MR imaging during a learning task in he althy elderly volunteers and in patients with Alzheimer's disease and to te st our hypothesis that brain activation is decreased in the medial temporal lobe (MTL) memory system in patients with Alzheimer's disease compared wit h control volunteers. METHODS: In 12 patients with mild to moderate forms of Alzheimer's disease and 10 elderly control volunteers, activation of the MTL memory system was studied. We used two learning tasks that required the encoding of new infor mation into memory. After the functional MR imaging experiment, participant s were tested for recognition of the encoded objects. RESULTS: In the elderly control volunteers, activation during memory encodi ng was observed in medial and lateral temporal lobe structures (fusiform, p arietal and occipital parts, and hippocampal formation) and in the frontal cortex, as reported previously in studies of young control volunteers. Focu sing on the MTL, we observed that activation was significantly decreased in patients with Alzheimer's disease compared with control volunteers in the left hippocampus and parahippocampal gyrus bilaterally during the first enc oding task but not during the second (P < .05, uncorrected). CONCLUSION: Functional MR imaging with a learning task seems feasible in el derly volunteers and in patients with Alzheimer's disease. The measured fun ctional signal decrease in MTL areas warrants further exploration of the (e arly) diagnostic usefulness of functional MR imaging in cases of Alzheimer' s disease and other dementias.