Serotonin Transporter Imaging in Multiple System Atrophy and Parkinson's Disease

Area of Science:

• Neuroscience
• Radiology
• Neurology

Background:

• Parkinson's disease (PD) and multiple system atrophy (MSA) involve degeneration of brainstem serotoninergic nuclei.
• While medullary serotonin system changes are known in MSA, broader brain alterations are less understood.

Purpose of the Study:

• To compare serotoninergic innervation in patients with MSA and PD using serotonin transporter (SERT) positron emission tomography (PET).

Main Methods:

• SERT PET imaging was performed on 18 MSA patients, 23 PD patients, and 16 healthy controls.
• Regional differences in SERT distribution volume ratios (DVR) were analyzed in brainstem, subcortical, and cortical regions.

Main Results:

• MSA patients exhibited lower SERT DVR than PD patients in the medulla, raphe pontis, ventral striatum, limbic cortex, and thalamus.
• Healthy controls had higher cortical SERT binding than both patient groups but lower striatal binding.
• No differences were found between MSA subtypes; SERT DVR correlated inversely with motor scores in MSA patients.

Conclusions:

• Serotoninergic deficits in the brainstem and forebrain are more pronounced in MSA compared to PD.
• These deficits show an MSA-specific correlation with motor impairment severity.