" A 2013 survey by the Parkinson’s disease Foundation (PDF) identified fatigue as the most pressing need for the Parkinson’s research community. While tremors, muscle stiffness, and irregular gait are the symptoms most associated with Parkinson’s disease, 50% of PD patients experience severe fatigue and a third say it is their single most debilitating symptom. Fatigue is the most significant reason cited for medical disability insurance claims by PD patients in the United States. Despite this overwhelming evidence, neurologists tend not to recognize fatigue as a prominent concern of PD patients. Two studies in newly diagnosed Parkinson’s patients reported fatigue to be a clinically relevant problem even when motor symptoms were minimal. These studies identified fatigue as a “pre-motor” symptom, appearing well before motor symptoms become obvious. Parkinson’s patients describe their fatigue as different than any tiredness they had experienced before their diagnosis. Unlike fatigue in the general public, PD fatigue often improves with exercise. Mental fatigue that affects Parkinson’s patients is called “central fatigue” and relates to the experience of feeling weary or exhausted during an intellectually challenging task, along with decreased capacity to initiate or sustain cognitively challenging activities. Parkinson’s patients suffering from cognitive fatigue have reduced attention span, and may have deficits in learning, memory, and information processing. Cognitive fatigue will often emerge as tasks become increasingly more complex or attention demands are greater." http://www.hopeforfatigue.org/parki...he-silent-symptom-of-parkinson-s-disease.html just shows that 'chronic disabling fatigue' is not unique to ME/CFS.............. Big difference tho is the reaction to exercise. Another reason (as if we needed one) to ditch the Chronic fatigue moniker.