Science Sees PSP Differently from How I See PSP

Science sees PSP differently from how a patient, or at least this patient, sees PSP.

Perhaps that is inevitable, and perhaps there is nothing wrong with it. Scientists and patients are looking for different things.

Maybe I should stay away from the science altogether. I am not a neurologist, researcher or statistician. I am a patient. Only a patient. Perhaps I should stay in my lane.

But as a patient advocate, and as someone with almost nothing to do all day, these subjects interest me. I have come across the various PSP Rating Scales, known as the PSPRS, many times in scientific journals. Today I tried to understand them properly, partly to fill some of the time I have and partly to work out what they might mean for the patient experience.

The chart below shows how the main PSP Rating Scales have evolved, based on the journals I have read. Any errors are mine alone. The original and still widely used scale contains 28 items. A more recent version reduces this to 15. Another, recommended by the US Food and Drug Administration during a particular drug-development process, reduces it to 10.

There are understandable reasons for this evolution.

Researchers need a scale that can detect whether a potential treatment changes the progression of PSP. The measurement must be consistent, sensitive and reliable. It must also work over the relatively short span of a clinical trial, often just 12 months.

The 15-item scale therefore kept the symptoms that appeared most useful for measuring change during that window. It removed items that could be influenced by other conditions, did not change quickly enough, contributed relatively little to the overall measurement, or could be assessed more accurately using a separate specialised tool.

A patient sees things differently.

I do not experience PSP as a clinical-trial endpoint. I experience it from the moment I wake until the moment I finally manage to sleep.

The 15-item scale removes sleep difficulty, urinary incontinence, irritability, limb rigidity and every question dealing with thinking and behaviour. Yet sleep affects me massively. Rigidity, and not only in my neck, shapes almost every movement I make. Irritability affects me and the people around me.

The 10-item version goes further. It also leaves out all the eye-movement items, including eyelid dysfunction. My eyes are among the most disabling parts of my PSP.

Pain does not appear even in the original 28-item scale. Nor do photophobia, sensory overload or the frightening episodes when I remain conscious but become almost unable to move.

Many people will understandably be troubled by the removal of cognitive and behavioural items from the shortened scales. I have been fortunate to retain most of my cognitive function and much of my behavioural function, but I know these symptoms can transform the lives of patients and their families.

None of this makes the scales wrong.

It means that science and the patient are measuring different things.

The scientist asks: which symptoms will most reliably show whether PSP has changed over 12 months?

I ask: what is making my life difficult today?

Both questions are legitimate. The difficulty begins only when the answer to the first is mistaken for a description of the whole disease.

The 15-item scale deliberately narrows its focus to three largely motor areas: gait and limb function, eye movement, and speech and swallowing. That may be exactly right for a particular clinical trial. But I cannot quite shake the feeling that, for the broader understanding of PSP, it represents a small step backwards.

Many patients, carers and clinicians have worked hard to explain that PSP is not simply a movement disorder. It reaches into cognition, behaviour, sleep, continence, mood, personality, relationships, independence and the entire emotional life of a family. Those experiences are harder to measure cleanly. That does not make them less real.

The researchers know this. The authors of the 15-item study say that many of the removed items remain useful in routine clinical care, and that cognition should not be ignored but measured separately with more sensitive tests.

That distinction is essential. A clinical-trial scale is a tool built for one purpose, not a portrait of the illness. It only becomes a problem when it quietly replaces the patient’s own account.

And the patient’s account is not merely something to be understood, although we would like to be understood. It should also help shape what gets built.

A medicine that slows the loss of walking or swallowing could be transformative. But we may also need help with sleeplessness, pain, sensory overload, behavioural change and the emotional turmoil that comes with losing independence.

Science examines patterns across many patients. I live one version of PSP from the inside.

Neither should crowd out the other. Better treatments depend on both, and the two views only stay connected if someone keeps saying so.

So perhaps I really should stay in my lane.

But the lane I am in is the disease itself, seen from inside it. And that is the one vantage point no rating scale can occupy.

In all the time I have been writing these posts, I can count on no hands the number of times someone from the scientific community has contacted me because of them. Perhaps that will never change.

But someone has to describe the part of PSP that does not fit on the scale.