Table 5.

Summary of regional mAChR SPECT and PET binding studies in PD and parkinsonian dementia.

Reference	mAChR ligand	Population	Main findings and clinical correlates
(Shinotoh et al., 1994)	[11C]-NMPB	PD	Administration of trihexyphenidyl (antimuscarinic agent) resulted in 28% inhibition of mAChR occupancy in the patients.
(Asahina et al., 1995)	[11C]-NMPB	PD	Receptor binding calculated by a graphical method, was 20% higher in the frontal cortex of PD patients than controls (p < 0.05). Increased expression of mAChRs in the frontal cortex of PD patients may be a compensatory response to a loss of ascending cholinergic input to that region, and may reflect frontal lobe dysfunction in PD.
(Asahina et al., 1998).	[11C]-NMPB	PD/PDD	Increased mAChR binding in the frontal lobe in PD without dementia that was more prominent in a patient with PDD. Increases in the striatum and parietotemporal cortices were not significant.
(Colloby et al., 2006)	[123I]-QNB	DLB, PDD	Increased mAChR receptor binding in right occipital lobe in DLB and right and left occipital lobes in PDD patients in a voxel-based analysis compared control subjects.