(PSYCHIATRIC TIMES) - An early human trial with a new PET radiotracer has found that Alzheimer's disease and vascular dementia both lead to substantial losses of nicotinic acetylcholine receptors in the cerebral cortex. The study from Germany suggests similarities in the pathogenesis of the two diseases relating to the cholinergic system.
Dr. Osama Sabri, chair of nuclear medicine, and colleagues at the University of Leipzig discovered an overlapping relationship using fluorine-18 F-A85380 PET to examine differences in nicotinic acetylcholine receptor availability in the brains of 17 Alzheimer's disease patients and four patients with vascular dementia.
Ten cognitively normal adults were imaged as experimental controls.
As abundant receptors in the normal brain, nicotinic acetylcholine receptors play a role in attention, memory, and cognition as well as cigarette addiction. Nicotine readily binds to nAChRs, as illustrated by up to a 44% decline in F-A85380 uptake after a normal subject smoked one cigarette, said Dr. Kai Kendziorra, a nuclear medicine resident who presented the study's results at the 2006 Society of Nuclear Medicine meeting.
By focusing on nAChRs, F-18 F-A85380 may offer a new approach to dementia diagnosis. MR imaging, combined with a clinical and neurophysiological assessment, diagnoses vascular dementia. F-18 FDG-PET metabolic measurement of neuronal viability is the preferred method for diagnosing Alzheimer's disease. Experimental carbon-11 polyisobutylene (PIB) and F-18 FDDNP-PET focus on the amyloid plaque and neurofibrillary tangles associated with Alzheimer's disease.
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