Putamen–midbrain functional connectivity is related to striatal dopamine transporter availability in patients with Lewy body diseases

• Patients with Lewy body diseases underwent FMRI and dopamine transporter (DAT) PET.
• Putamen–midbrain fMRI functional connectivity is proportional to DAT loss in patients.
• Caudate functional connectivity was unrelated to striatal DAT in patients.
• FMRI may be a useful biomarker of nigrostriatal dopamine loss in patients.

Prior work has shown that functional connectivity between the midbrain and putamen is altered in patients with impairments in the dopamine system. This study examines whether individual differences in midbrain–striatal connectivity are proportional to the integrity of the dopamine system in patients with nigrostriatal dopamine loss (Parkinson's disease and dementia with Lewy bodies). We assessed functional connectivity of the putamen during resting state fMRI and dopamine transporter (DAT) availability in the striatum using 11C-Altropane PET in twenty patients. In line with the hypothesis that functional connectivity between the midbrain and the putamen reflects the integrity of the dopaminergic neurotransmitter system, putamen–midbrain functional connectivity was significantly correlated with striatal DAT availability even after stringent control for effects of head motion. DAT availability did not relate to functional connectivity between the caudate and thalamus/prefrontal areas. As such, resting state functional connectivity in the midbrain–striatal pathway may provide a useful indicator of underlying pathology in patients with nigrostriatal dopamine loss.

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