Declarative memory changes are the hallmark of Alzheimer's disease, although their
functional neuroanatomy is not restricted to a single structure. Factor analysis provides
statistical methods for evaluating patterns of cerebral changes in regional glucose
uptake.
Thirty-three Alzheimer's patients and 33 age- and gender-matched control subjects
were studied with magnetic resonance imaging and positron emission tomography with
[(18)F] deoxyglucose. During the tracer-uptake period, subjects performed a serial
verbal learning task. Cortical activity was measured in 32 regions of interest, four
in each lobe on both hemispheres.
Factor analysis with varimax rotation identified seven factors explaining 80% of the
variance ("parietal cortex," "occipital cortex," "right temporo-prefrontal areas,"
"frontal cortex," "motor strip," "left temporal cortex," and "posterior temporal cortex").
Relative to control subjects, Alzheimer's patients showed significantly reduced values
on the factors occipital cortex, right temporo-prefrontal areas, frontal cortex, and
left temporal cortex. The factor temporo-prefrontal areas showed large differences
between patients with good and poor performance, but little difference when control
subjects were similarly divided.
Findings suggest that Alzheimer's disease is characterized by altered patterns of
cortical activity, rather than deficits in a single location, and emphasize the importance
of right temporo-prefrontal circuitry for understanding memory deficits.