Limitations of the study and future directions
An important limitation of this study is the relatively small sample
size. Nevertheless, an appropriate statistical analysis applied by us
(for inter-group comparisons and for correlations calculations) was able
to reveal an effect of dopaminergic system pathophysiology in PD PET/CT
neuroimaging, PSD-EEG and neuropsychological parameters outcomes even in
this relatively small sample size. However, due to this relatively small
sample size, the results of this study cannot be generalized for the
whole PD patients population. Another important limitation of our study
is the choice of only two neuropsychological cognitive tests (TMT and
ST). This choice narrowed down a range of our considerations on
associations of the PD-specific EEG brain waves slowing and dopaminergic
deficiency with disordered executive functions in tested by us PD
patients. Hence, further studies are needed using multimodal scientific
approach, with an application of electroencephalography (using EEG
recordings with resting and cognitive paradigms), PET/CT neuroimaging
methods (using dopaminergic and other PD-specific radiotracers) and
broad PD-specific battery of cognitive tests.