Psychiatric symptoms associated with cortical-subcortical dysfunction in Alzheimer's disease

Positron emission tomography was used to evaluate 3 Alzheimer's disease (AD ) patients: 1. with major depression, 1 with emotional lability, and 1 with apathy. Compared with 5 non-mood-disordered AD patients, the patient with depression had diminished relative regional cerebral blood flow (rel-CBF) i n the anterior cingulate and superior temporal cortices, bilaterally. This patient also showed diminished rel-CBF in the left dorsolateral prefrontal and right medial temporal and parietal cortices. The patient with emotional lability had diminished rel-CBF in the anterior cingulate and dorsolateral prefrontal cortices, bilaterally, and left basal ganglia The patient with apathy had diminished rel-CBF in the basal ganglia and dorsolateral prefron tal cortex, bilaterally. Results are consistent with the hypothesis of a co mmon frontal-temporal-subcortical substrate (e.g., involving aminergic nucl ei) in the etiology of depression in AD. Frontal-subcortical dysfunction ma y also be associated with emotional lability and apathy in AD, although the se may be related to a greater involvement of frontal-basal ganglia circuit s.