PET shows that striatal dopamine D1 and D2 receptors are differentially affected in AD.
OBJECTIVE
To study dopamine D1 and D2 receptors in the putamen and the caudate nucleus in patients with AD and age-matched healthy controls by means of PET.


METHODS
A dopamine D1 receptor antagonist ([11C]NNC 756) and a D2 receptor antagonist ([11C]raclopride) were used as ligands. The uptake of these ligands was calculated as a distribution volume ratio of the putamen and the caudate nucleus to the cerebellum.


RESULTS
The mean [11C]NNC 756 uptake in AD was reduced by 14% from the mean control value both in the putamen (p = 0.004) and the caudate nucleus (p = 0.009). There was no significant reduction in the mean [11C]raclopride uptake in either the putamen or the caudate nucleus in AD. There was no correlation between [11C]NNC 756 or [11C]raclopride uptake and Mini-Mental State Examination or motor Unified PD Rating Scale scores in patients with AD.


CONCLUSIONS
There are changes in striatal D1 but not in D2 receptors in AD.
Kemppainen
N
N
Department of Neurology, University of Turku, Finland.
Ruottinen
H
H
Nâgren
K
K
Rinne
J O
JO
D000368:Aged; D000544:Alzheimer Disease / Q000000981:diagnostic imaging* / Q000503:physiopathology; D001931:Brain Mapping; D002421:Caudate Nucleus / Q000000981:diagnostic imaging / Q000503:physiopathology; D003342:Corpus Striatum / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008609:Mental Status Schedule; D011699:Putamen / Q000000981:diagnostic imaging / Q000503:physiopathology; D017447:Receptors, Dopamine D1 / Q000502:physiology*; D017448:Receptors, Dopamine D2 / Q000502:physiology*; D014055:Tomography, Emission-Computed
D017447:Receptors, Dopamine D1; D017448:Receptors, Dopamine D2