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Original Contribution
December 2003

Cortical Cholinergic Function Is More Severely Affected in Parkinsonian Dementia Than in Alzheimer Disease: An In Vivo Positron Emission Tomographic Study

Author Affiliations

From the Departments of Neurology (Drs Bohnen, Kaufer, Moore, and DeKosky and Mr Ivanco) and Radiology (Drs Bohnen, Davis, and Mathis and Mr Lopresti), University of Pittsburgh School of Medicine and the Veterans Administration Pittsburgh Healthcare System (Dr Bohnen), Pittsburgh, Pa; and the Department of Radiology, University of Michigan, Ann Arbor (Dr Koeppe).

Arch Neurol. 2003;60(12):1745-1748. doi:10.1001/archneur.60.12.1745

Background  Pathology reports have shown that cholinergic forebrain neuronal losses in parkinsonian dementia (PDem) are equal to or greater than those in Alzheimer disease (AD). We hypothesized that patients with PDem would have cholinergic deficits that were similar to or greater than those of patients with AD.

Objective  To determine in vivo cortical acetylcholinesterase (AChE) activity in healthy control subjects and in patients with mild AD, PDem, and Parkinson disease without dementia using AChE positron emission tomography.

Setting  University and Veterans' Administration medical center.

Design and Patients  Group comparison design of patients with AD (n = 12), PDem (n = 14), and Parkinson disease without dementia (n = 11), and controls (n = 10) who underwent AChE imaging between July 1, 2000, and January 31, 2003. Patients with AD and PDem had approximately equal dementia severity.

Main Outcome Measures  Cerebral AChE activity.

Results  Compared with controls, mean cortical AChE activity was lowest in patients with PDem (−20.0%), followed by patients with Parkinson disease without dementia (−12.9%; P<.001). Mean cortical AChE activity was relatively preserved in patients with AD (−9.1%), except for regionally selective involvement of the lateral temporal cortex (−15%; P<.001).

Conclusion  Reduced cortical AChE activity is more characteristic of patients with PDem than of patients with mild AD.