Skip to main content

Table 1 Summary of pathological and imaging evidence of parasympathetic nervous system and olfactory system involvement in PD

From: The underlying mechanism of prodromal PD: insights from the parasympathetic nervous system and the olfactory system

Structure

α-syn pathology

Structural imaging

Functional imaging

Molecular imaging

Vagus nerve

Positive

NA

NA

NA

Gastrointestinal tract

Controversy

NA

NA

Decreased 11C-donepezil standard uptake values in the small intestine and pancreas following a rostral-caudal gradient [43]

Olfactory bulb

Positive

Bilateral reduction of olfactory bulb volume [64, 65, 68]

NA

NA

Olfactory tract

Positive

Bilateral increase of mean diffusivity [66, 67]

NA

NA

Olfactory cortex

Positive

Decrease of olfactory sulcus depth; decrease of piriform cortex volume [68, 71]

Reduced activation in amygdala and hippocampal formation after olfactory stimulation [72–74]; decreased regional homogeneity and functional connectivity within olfactory cortex and decreased connectivity within limbic/paralimbic networks [75]

Reduced glucose metabolism in bilateral medial prefrontal cortex and parieto-occipito-temporal cortex [76]; positive correlations between UPSIT scores and acetylcholinesterase activities in hippocampal formation, amygdala and neocortex [70]; positive correlations between UPSIT scores and vesicular monoamine transporter type 2 binding potential in striatum [70]; positive correlations between UPSIT scores and dopamine transporter binding potential in hippocampus, amygdala and striatum [78]