Serotonin 2A receptors and visual hallucinations in Parkinson disease.
BACKGROUND
Complex visual hallucinations (VHs) occur in several pathologic conditions; however, the neural mechanisms underlying these symptoms remain unclear. Although dopamine may have a role, indirect evidence indicates that serotonin may also contribute to the pathogenesis of complex VHs, probably via involvement of the serotonin 2 receptor.


OBJECTIVE
To examine for the first time in vivo changes in serotonin 2A receptor neurotransmission among patients having Parkinson disease (PD) with VHs.


METHODS
Case-control study.


METHODS
Academic research.


METHODS
Seven patients having PD with VHs and 7 age-matched patients having PD without VHs were recruited.


METHODS
We used the selective serotonin 2A receptor ligand setoperone F 18 during positron emission tomography among nondemented patients having PD with VHs.


RESULTS
Patients having PD with VHs demonstrate increased serotonin 2A receptor binding in the ventral visual pathway (including the bilateral inferooccipital gyrus, right fusiform gyrus, and inferotemporal cortex) as well as the bilateral dorsolateral prefrontal cortex, medial orbitofrontal cortex, and insula.


CONCLUSIONS
This pilot study provides the first in vivo evidence suggesting a role for serotonin 2A receptors in mediating VHs via the ventral visual pathway in PD. Treatment studies should be performed using selective serotonin 2A receptor antagonists, which have important implications for the clinical management of VHs and psychosis in PD.
Ballanger
Benedicte
B
Vivian M. Rakoff PET Centre, Toronto Western Hospital, Toronto, Ontario, Canada
Strafella
Antonio P
AP
van Eimeren
Thilo
T
Zurowski
Mateusz
M
Rusjan
Pablo M
PM
Houle
Sylvain
S
Fox
Susan H
SH
D000368:Aged; D001921:Brain / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology*; D001931:Brain Mapping; D016022:Case-Control Studies; D005260:Female; D006212:Hallucinations / Q000000981:diagnostic imaging / Q000209:etiology* / Q000503:physiopathology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D010300:Parkinson Disease / Q000150:complications* / Q000000981:diagnostic imaging / Q000503:physiopathology*; D010865:Pilot Projects; D049268:Positron-Emission Tomography; D011744:Pyrimidinones; D044402:Receptor, Serotonin, 5-HT2A / Q000235:genetics / Q000378:metabolism*; D012701:Serotonin / Q000378:metabolism; D012702:Serotonin Antagonists; D013702:Temporal Lobe / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D014793:Visual Cortex / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology; D014795:Visual Pathways / Q000000981:diagnostic imaging / Q000378:metabolism / Q000503:physiopathology
D011744:Pyrimidinones; D044402:Receptor, Serotonin, 5-HT2A; D012702:Serotonin Antagonists; D012701:Serotonin; C045359:setoperone