From the full text of the cited article:

Abstract PATIENTS AND METHODS RESULTS DISCUSSION Acknowledgements References

In contrast, resting tremor without prominent other parkinsonian features in NRG may implicate other nondopaminergic neurotransmitter dysfunctions and this may explain why patients in NRG showed no responsiveness to dopaminergic medications.

Our results further suggest that the anatomical basis of the resting tremor may differ from the classic neuropathology of PD. In a previous study using 18F-dopa PET, decreases of 18F-fluorodopa uptake in the striatum correlated with the degree of bradykinesia and rigidity, but not with the degree of tremor.[11] Recently, other studies have investigated the association between resting tremor in PD and the deficit of nondopaminergic neurotransmitters, especially serotonin.[12][13]

I wanted to share that my most troubling symptom is tremor (I have a variety pack: resting, action, and postural). However, I do have mild bradykinesia and even more mild rigidity. My tremor response to levodopa is phenomenal - so much so that a MDS I recently consulted said based on his observation of me "on" meds he could not give me a PD diagnosis.

I find this study odd. It states that: "We found that resting tremor in patients with PD was more responsive to dopaminergic treatment when accompanied by a moderate degree of bradykinesia and rigidity than when it presented without prominent accompanying parkinsonian features."

Based on what I've read, no respectable neurologist would diagnose a person with PD when there are no other prominent parkinsonian features! There is the cardinal signs rule- we have to exhibit at least 2 of the 4 cardinal or hallmark signs of the disease to earn our PD badge. What does "prominent" mean then?

It's interesting to note that serotonin may play a role in resting tremor.

Laura