Aggression is a very problematic behavioral symptom affecting a significant proportion of Alzheimer's disease patients. Previous work in our laboratory has shown that a subgroup of Alzheimer's patients displaying aggressive behaviors had a markedly higher level of alpha2-adrenergic receptors in the cerebellar cortex (approaching or exceeding those of controls), compared to Alzheimer's patients with similar cognitive impairments, but no history of aggressive behaviors. This study has sought to assess whether noradrenergic neuronal inputs to the cerebellum reflect similar changes in this Alzheimer's subgroup. Cerebellar cortex from non-aggressive Alzheimer's subjects showed a markedly lower level of tyrosine hydroxylase-positive neuronal fibers than normal controls (approximately 75% decreased), visualized by immunohistochemistry. Cerebellar cortex from the aggressive Alzheimer's subgroup, on the other hand, had a tyrosine hydroxylase fiber concentration not significantly different than controls. These results suggest that there is a relative preservation of inhibitory noradrenergic neuronal input to the cerebellar cortex in this aggressive subgroup of Alzheimer's disease patients. Much evidence exists that the cerebellum assists in behavioral control. The possibility that this lack of noradrenergic decline in the cerebellum could lead to a system imbalance and result in a selective behavioral disturbance is discussed.