Vascular dementia with left thalamic infarction: Neuropsychological and behavioral implications suggested by involvement of the thalamic nucleus and the remote effect on cerebral cortex. The Osaki-Tajiri project

Vascular dementia (VaD) is a condition whereby decreased cerebral perfusion causes cognitive deterioration. We hypothesized that lesions of the anterior nucleus (AN) including the mammillo-thalamic tract cause a decline in the recollection of past episodes/events, and that the left thalamic infarction can cause frontal dysfunction through the "diaschisis." We investigated 18 VaD cases with only left thalamic infarction. ^99mTc-ECD single photon emission computed tomography (SPECT) was used to assess regional cerebral blood flow (CBF). To test the first hypothesis, the scores on the Cognitive Abilities Screening Instrument (CASI) domain Recent memory or the rating on the Clinical Dementia Rating (CDR) domain Memory were analyzed. To test the second hypothesis, we selected the six regions of interest that correlated with the two measures, i.e., word fluency and/or depressive state, as assessed with the Geriatric Depression Scale (GDS). We found that all patients had amnesia, especially in the AN group, six of the eight patients had scores of 1+ on the CDR Memory scale, and all but one disclosed the CASI domain Recent memory impairment. There were significant correlations between the left anterior cingulate CBF and word fluency scores, and between the right rectal gyrus CBF and GDS scores. We suggest that these observations are due to a remote effect of the thalamic lesion.