Parkinson’s disease is a common neurodegenerative movement disorder. The cardinal motor symptoms of Parkinson’s disease include bradykinesia, rigidity and rest tremor. The association between rest tremor and nigrostriatal degeneration has remained unclear. Parkinson’s disease is also often associated with non-motor symptoms including cognitive and mood problems, with unclear mechanisms despite increased research efforts over the past decades. Dopamine transporter single-photon emission tomography is the most common molecular imaging method used in the diagnostics of Parkinson’s disease. The results of this imaging method reflect the monoamine transporter density in brain areas. [123I]FP-CIT, the most commonly used tracer in this context, enables investigating not only dopaminergic but also serotonergic and noradrenergic function.

In this thesis, I explore the association of monoaminergic function with the motor, cognitive and behavioral symptoms of Parkinson’s disease as well as the abnormalities in bodily sensations of emotions in the disease. Monoaminergic function and the symptoms of Parkinson’s were investigated using the largest available follow-up data of patients with Parkinson’s disease, the Parkinson’s Progression Markers Initiative. The bodily sensations associated with emotions were studied using a relatively recently developed bodily mapping technique, emBODY.

The results of this thesis show that rest tremor amplitude is associated with increased ipsilateral striatal dopamine transporter availability. In addition, depression seems to be associated with abnormalities in dopamine and serotonin, anxiety with abnormalities in serotonin and noradrenaline, and REM sleep behavior disorder mainly with abnormalities in dopamine function. The emBODY results suggest abnormal bodily sensations of emotions in Parkinson’s disease: anger-related sensations on the chest were lesser in Parkinson’s disease than among control subjects, and longer disease duration was associated with a shift towards the abdomen. The results provide new insights to the neural mechanisms of both motor and non-motor symptoms in Parkinson’s disease, and reveal a new non-motor phenomenon, with each finding having potential future clinical implications.