The onset of Parkinson's disease is usually discovered because of symptoms related to movement, such as shaking of the hands or difficulty walking. Recently, however, it has been discovered that many people with Parkinson's disease complain of constipation well before motor abnormalities became apparent. Of course, this does not mean that everyone with a tendency to experience constipation will go on to develop Parkinson's disease, but for men aged from their 50s to around 70, those with constipation have been reported to be around 3-4 times more likely to be affected by Parkinson's later in life.

Another subject warranting attention is a declining sense of smell. Although few people would say that they have difficulty smelling things any more, some elderly people complain that food no longer tastes good, or that they cannot tell what things taste like any more. Elderly people tend to express difficulties with sense of smell in terms of meals lacking in flavor or a loss of taste.