Constipation is one of the most frequent non-motor symptoms of PD (40-90% of the patients). It frequently precedes (even several years before) the beginning of tremor and rigidity. PD related constipation is actually the results of neurodegenerative changes in the vegetative centers of the brain and in the peripheral intestinal neurons (the enteric nervous system). Another mechanism is probably the dysregulation of the gut microbiota (the intestinal bacteria ecosystem) in PD.
Constipation can be invalidating and also diminishes the absorption of the dopaminergic drugs and aggravates the other symptoms of PD.
Furthermore, to confirm that constipation and PD are related, it is necessary to exclude any other medical condition (such as colon cancer, irritable bowel syndrome and so on) or the effects of other drugs and medicaments.
Fluid and dietary fibers intake and increasing gait endurance and physical activities is the general approach. Psyllium and stool bulk agents can be useful, but they require good hydration. Osmotic laxatives should be used with caution in case of renal and cardiac dysfunction. Several other pharmacological treatments exist. Restoration of normal gut macrobiota in PD patients could be a future promising therapy.