Understanding Frailty in Parkinsonism | Congress 2026

Alison Yarnall: Thank you for asking me.

Nicole Duff: The underlying current of your talk was frailty, which may not be completely obvious because of the title of the talk.

So, maybe we can start by just explaining what frailty is.

Alison Yarnall: Frailty can be defined as an age-associated biological [00:01:00] syndrome, which is characterized by reduced physiological reserve and an increased risk of adverse outcomes such as falls, delirium, and disability. It's not just an age-associated concept.

The reason why I think it's important is it's applicable to many of our Parkinson's patients, whether you're being treated by a geriatrician or a neurologist.

Nicole Duff: Great. Thank you. As healthcare professionals, how do we know what to look out for as signs and symptoms in our patients that are common within frailty?

Alison Yarnall: What we'd look out for are the key definitions, the key symptoms and signs that we might take from some of the ways we would measure frailty. For example, is your patient losing weight? Have they lost 5% or more of their body weight over the last 1 year.

Are they slowing down? Again, that's a feature of Parkinson's. But do they have a slow gait speed? We would say being slower than the lowest 20% of an age- and sex-matched population. Do they have weakness characterized by reduced [00:02:00] grip strength? Do they have low levels of physical activity?

And the last feature as part of the Fried phenotype is self-reported exhaustion.

Nicole Duff: Those are quite specific signs and symptoms that we can look out for. But does it also maybe just mean that the person's not just getting old?

Alison Yarnall: That's a great question, and it's true that frailty does increase with longevity, but it's not an inevitable part of aging, and that's really important to realize.

So, in aging, we just get a gradual decline in physiological reserve, whereas frailty is actually a biological syndrome, and some might say it's a bioenergetic failure. 

Nicole Duff: Thank you. I think it's really important for us as healthcare professionals to be really vigilant about it and not just, as you say, assume that it's something that's part of a natural process. And, look out for those specific signs and symptoms which can be easily missed, especially if a patient has Parkinson's and we just [00:03:00] attribute it to something else.

Would frailty be more common in our Parkinson's patients?

Alison Yarnall: Yes, it is. There's been quite a bit of evidence to demonstrate this. There've been a couple of systematic reviews and the first one, it was back in 2019 from Emily Henderson's group, and they showed a frailty prevalence of between 30% and 60% of the PD population studied.

Now, this was largely across Western countries, Western worlds. More recently, there's been a meta-analysis, and that estimated a pool prevalence at 38%. But really the definition of frailty varies. It depends on the frailty definition that you use. It depends on the background characteristics of the population and things like the stage of Parkinson's disease itself.

Now, there is talk that and thoughts that actually the way we are measuring frailty in Parkinson's disease and in general might actually overestimate the prevalence of frailty, and that's because of the overlap of symptoms, so slowed gait speed is obviously part of [00:04:00] Parkinson's,

reduced grip strength might be. These can be sort of motor and non-motor symptoms of Parkinson's itself. So there is this difficulty, this tension between these two definitions. There are other ways to measure frailty. The first way we talked about recognizing it, it was this Fried phenotype, but there's also what we call a health deficit accumulation, whereby there's a list of variables and the more health-associated health deficits someone has, the greater the risk they have of becoming diagnosed with frailty.

Nicole Duff: I think then we have to turn to the science and make sure that we are not just saying, "Well, you know, we're going to say are we overestimating or underestimating?" And instead make sure that we're gathering as much data as we can. With regards to frailty, do Parkinson's patients experience it worse than perhaps the normal population?

Alison Yarnall: Certainly we know that frailty adversely affects outcomes in [00:05:00] Parkinson's disease. There've been a number of studies that have shown a variety of these adverse outcomes.

There was a nice study from Cambridge that I mentioned in my talk. It was only a relatively small number of patients, but in older hospitalized PD patients, those that were classified as frail according to the Clinical Frailty Scale had a greater mortality risk after adjusting for covariates.

In addition to increased mortality risks, we know that frail patients are more likely to go on and develop dementia. That's work that's come out of the ParkWest study. We in Newcastle have looked at delirium. So, you remember I mentioned delirium as an adverse outcome associated with frailty, and we've shown that delirium's more common in people with Parkinson's who are hospitalized compared to the controls.

But frailty was also an independent predictor of delirium in this group. And there has also been work following people up who are frail with Parkinson's, in a group from Italy, and they showed that these people progress more rapidly motorically. They had greater treatment-related [00:06:00] complications. They had higher levodopa doses and an increased mortality risk.

So, very much, frailty impacts on outcomes in Parkinson's disease. And it's possible that the frailty in Parkinson's disease is indicative of a different pathology, a different underlying biology that perhaps drives a more rapidly progressive Parkinson's or parkinsonism.

Nicole Duff: It's almost a completely separate phenotype.

Alison Yarnall: Yeah

Nicole Duff: So conversely, are Parkinson's patients worse if they have frailty? I think we spoke a little bit about is frailty worse if a patient has Parkinson's? Now, are Parkinson's patients worse if they have frailty?

Alison Yarnall: Well certainly, and sort of conversely, it has been shown in the literature that actually frailty increases the risk of someone to go on and develop a diagnosis of Parkinson's disease, and in fact, I didn't talk about it in my talk, but other neurodegenerative diseases itself.

So we know again from longitudinal work and follow-up of large cohorts that if someone's diagnosed with [00:07:00] frailty, if you follow them up over time, they're more likely to be diagnosed with Parkinson's. And that's been replicated across a number of studies. And indeed, most recently, there was a study from Ren et al.

They followed up over 50,000 patients and found that Parkinson's was preceded by this multi-domain prodrome characterized by increasing levels of frailty, measured with something called a physical frailty index. This seemed to be accelerated just around the time of PD diagnosis and immediately afterwards as well.

Nicole Duff: That is absolutely incredible. What a fascinating find. I need to go and hunt down those studies immediately. So how can we measure frailty?

Alison Yarnall: I mentioned in my talk there are three main ways. So the first, the probably the most simple and straightforward is this Fried phenotype. So this is five symptoms or signs, and they're summed together to give a status of robust through to pre-frail or frail. The second way we would define it, using a different way, is a health deficit accumulation. There it's just [00:08:00] a simple count of the number of deficits someone has divided by the total number of variables measured, and that gives you a frailty index.

This is a continuous score from zero to 1, with higher levels indicating a greater degree of frailty. And the last way, probably the most pragmatic way, is something called the Clinical Frailty Scale. This was designed to be used by healthcare professionals and we use it in the hospital where I work, and this is just a 9-item scale that gives you a definition of someone from completely independent right the way through to terminally ill.

And on that scale, a score of 5 or more would generally indicate that someone's frail. So those are the ways we would look to measure it.

Nicole Duff: Brilliant. Thank you. As a physio, I'm often limited by the kind of scales that I'm allowed to use. So, are these scales allowed to be administered by all healthcare professionals?

Alison Yarnall: Yeah, they are. And certainly the Clinical Frailty Scale is widely used. As I said, we use that in our hospital. There's no cost associated with it, and it's quick to deliver. It's [00:09:00] pragmatic. It pertains to someone's health status at their baseline. For example, when someone comes into our hospital, you would ask about their health status in the span of 2 weeks prior to hospital admission to get their baseline state.

The disadvantage is that it can be confounded by preexisting neurological disability, but none of these tools are ideal, and that's a real gap in the literature is having a frailty tool that's specific for Parkinson's disease or, indeed, a definition of frailty in Parkinson's that stands alone.

Nicole Duff: Great. Thank you. So, if I have a patient with well-established Parkinson's and frailty, do I then have to treat them differently versus if they only had Parkinson's disease?

Alison Yarnall: Yeah, that's a really good question. And what we think of when someone has Parkinson's and frailty is that they've got these other adverse outcomes potentially associated with it.

So falls, disability, functional impairment, slowed mobility, maybe need assistance for activities of daily living. And so at [00:10:00] that stage, we would be thinking about a comprehensive geriatric assessment, which I'm sure you're familiar with as a physiotherapist. So a full multidisciplinary review and thinking about things like personalized physical activity program, specifically looking at resistance exercises, perhaps nutritional supplementation, caloric or protein supplementation, review of the medications, review of the falls risk, and really a full multidisciplinary team assessment.

It may well impact on how you treat someone with Parkinson's, because if someone has Parkinson's and frailty, I'm thinking do they need all these different Parkinson's drugs? Should we be getting down to levodopa monotherapy? What about the non-motor symptoms? And thinking about our final speaker in our session, looking at the whole person, as it were.

Nicole Duff: Yes, I sat and listened to his talk, and so I'm understanding exactly the direction you're going, but it just becomes so much more complex, so many more avenues that you have to sort of find your way going down.

You mentioned now, but also [00:11:00] in your talk, that there are so many gaps in research. So putting you on the spot, if you had to say there was a number one step that we had to start with, what would you say it would be?

Alison Yarnall: I would say that we need to be stratifying by frailty and frailty status as part of clinical trials because there's loads of treatment trials coming out.

We're moving towards disease modification, and we need to make sure that these results are generalizable to the full PD population. So I would argue that we should be measuring frailty in these people and accounting for this in the results as well.

Nicole Duff: Brilliant. Thank you. So to all the researchers out there. And then any final thoughts from you?

Alison Yarnall: I just think it's really great that frailty and aging in Parkinson's disease is being recognized and recognized in a plenary session. I think it's really important because it's something applicable to all of the multidisciplinary team, all [00:12:00] of us that see PD patients and associated parkinsonian syndromes, and we all need to know about it.

Nicole Duff: Yes. Thank you. I think that your talk was fantastic. As I said earlier, it was so thorough and well broken down and easy to follow, and certainly opened everyone's eyes to how, not easy because obviously it's a complex condition, but how the signs and symptoms can easily be followed, how the outcome measures can be easily followed, and it's something that we really need to start implementing.

So thank you for a fantastic talk. Thank you for all your research, and once again, thank you for being here.

Alison Yarnall: Thank you very much, and thank you for the invitation. [00:13:00]