Increased lymphocyte dopamine β-hydroxylase immunoreactivity in Alzheimer's disease: Compensatory response to cholinergic deficit?

There is growing interest in the characterization of peripheral blood lymphocytes (PBL) as a biological tool with which to investigate changes in the neurotransmitter-receptor system in neurodegenerative disorders. Here we show a slight decrease in acetylcholinesterase (AChE) and a significant increase in dopamine β-hydroxylase (DBH) immunoreactivity in the PBL of patients with probable Alzheimer's disease (AD). Therapy with AChE inhibitors completely reversed the increase in DBH immunoreactivity. We hypothesize that the increase in DBH immunoreactivity may represent a compensatory response to cholinergic impairment. Our findings suggest that neurochemical interactions between the noradrenergic and cholinergic systems may be measured at a peripheral level in AD.