I often have the feeling, rightly or wrongly, that medicine is happy to investigate those areas where it is more easily successful than those which prove more challenging. These are in essence the low hanging fruit, easy wins for impatient researchers. And in a research culture where early success or failure can build or blight a career, it’s easy to see why some areas of research are more fashionable than others.

In the context of Parkinson’s for instance, we have known about rigidity, bradykinesia, postural instability and tremor. We have known about them because they are easy to identify, easy to characterise and, in simple clinical terms, easy to treat. Results are visible and readily quantifiable by physicians. They are, for Parkinson’s, the low hanging fruit.

Further up the tree, and less readily accessible, are some of the non-motor symptoms of Parkinson’s. These might include fatigue, affective disorders, bowel and bladder control issues, apathy, sleep disorders, loss of sense of smell and so on. And although often nebulous and, in many respects, non-specific, they nonetheless form key parts of the Parkinson’s experience. Indeed for many patients nonmotor symptoms have a larger role in determining quality of life than the motor symptoms.

Yet even nowadays nonmotor symptoms tend to be thought of as an adjunct to the central motor symptoms of Parkinson’s. Somehow they are not considered still to be central to the condition. Even now in 2018 we persist in calling Parkinson’s a movement disorder rather than the broad-spectrum neuropsychopathological condition that it is. We seem to insist on the preeminence of motor symptoms.

But why should this be? Why should we persist with this archaic terminology and its stultifying implications for our understanding of Parkinson’s?

A number of possible explanations come to mind but I like this one – that by placing undue emphasis on motor symptoms, the condition is medicalised. That is that it is taken out of the ownership of the patients and becomes the province of the treating physician. When it is a motor condition, a movement disorder, it is easy for a treating physician to claim therapeutic success and easy for a researcher to study. A reduction in the amplitude of tremor is something numerical and therefore scientific. For nearly 2 centuries since its original characterisation, Parkinson’s has been a movement disorder that is managed by physicians with scarcely a nod towards the nonmotor symptoms.

There is a tendency to believe that the nonmotor symptoms of Parkinson’s are something new or at least newly identified. The derivation and application of scales with which to quantify the nonmotor symptoms has taken them into the spotlight, the point at which the medical research community has begun to show interest.

But nonmotor symptoms are nothing new. In his original essay on the shaking palsy, Parkinson described nearly all of the currently understood nonmotor symptoms of the condition. Parkinson knew they were part of the condition, because he asked the right questions of the patients. Since then nearly 2 centuries worth of physicians have found it more convenient not to ask the right questions. So although nonmotor symptoms have been part – a central part – of the patient experience of Parkinson’s, they have only more recently become legitimate targets for researchers and physicians. Before they were merely irritating distractors, blemishes on their motorcentric views of the condition.

Nonmotor symptoms are often difficult to treat. It’s relatively easy to improve mobility or reduce tremor but apathy and fatigue remain less amenable targets. But if you ask any patient, you will find that the nonmotor symptoms impinge every bit as assertively on a patient’s quality of life as their mobility. They may be more tricky to treat. They may be less readily quantifiable. They may even be elusive research targets. But they are vital components in the Parkinson’s jigsaw.

I was a researcher in Parkinson’s for more than 20 years before I was a patient. More importantly, I had to become a patient before I really understood this condition. My dozens of research papers as a scientist were testaments to what we could measure in Parkinson’s, not what we should.

We have gorged for too long on the low hanging fruit. It’s time to set our aspirations higher.

Why have we largely ignored non-motor symptoms in PD?