Disclosure: Indu Subramanian, MD, has disclosed the following relevant financial relationships:

Serve(d) as a speaker or a member of a speakers bureau for: Acorda Pharma

Recorded January 14, 2025. This transcript has been edited for clarity.

Kathrin LaFaver: Hi. I'm Kathrin LaFaver, on behalf of Medscape. I have the pleasure today of talking with Dr Indu Subramanian, director of the Parkinson's Disease Research, Education and Clinical Center (PADRECC) at the Veterans Affairs Medical Center in West Los Angeles, as well as a clinical professor at UCLA.

We will be talking today about the impact of heat waves and natural disasters on neurologic disease, specifically neurodegenerative illness. This is a very timely discussion. At the time of recording, it's about 1 week after the news of the fires in LA hit us.

Indu, you are in the middle of LA, can you fill us in on how the situation looks for you?.

Indu Subramanian: I hate using the word "unprecedented," because this is what we constantly said with the pandemic. But these are times like I've never lived in. Colleagues of mine have lost their homes literally overnight. They are now, trying to figure out how to balance trying to find new schools for their children and rebuilding a life with nothing but the small bag they grabbed.

It's obviously very stressful. Some of the people who've lost everything in other parts of town are already marginalized folks in neighborhoods that are historically Black, historically without a lot of resources. In the beauty of it all, the city has come together to try to work together. I am currently safe. I'm prepared to evacuate with my family. We continue to try to work as physicians and support our communities and do our best to figure out how to move forward. But it's traumatic, and it's constantly changing and stressful. And I say this from the vantage point of someone who's still in my home with my family and not in imminent danger.

We just wrote this viewpoint on heat waves, and I've become so much more attuned to the effects of climate change on our society and as physicians, I don't think that we thought about this going through med school -- the impact of the ever-increasing toxins in the air, the ever-increasing risks to our patients who are on the fringe, often of healthcare and of society. These are sometimes very lonely, isolated individuals that we take care of. I've been thinking about how we can provide care and prevent bad things from happening to patients at risk for neurodegeneracy, or who already have a neurodegenerative condition such as Parkinson's or Alzheimer's disease. And in the global picture -- thinking about brain health and some of the work that we've done on lifestyle and how we can help our brains to be better in the long run and preserve brain function -- the effects of climate change, air pollution, heat waves, and these wildfire particulate matter exposures are very scary. There are some data from animal models, and also the data that we're getting on the effects of some of this on populations at risk for diseases such as Alzheimer's and Parkinson's.

LaFaver: I'm really happy to hear that you and your family are safe. As you mentioned, there's been a number of papers in the past couple of years studying the effects of natural disasters, particularly wildfires, on the incidence of neurologic disorders and especially dementia. Do you want to tell a little bit more about some of these findings?

Subramanian: As we speak, there are urban fires happening. The Pacific Palisades has homes with a lot of different mixes of chemicals and toxins that are burning from electronics, computers, batteries, and TVs. Historically, we've had data on wildfires with different kinds of trees -- eucalyptus, pine needles -- burning in forests, and the risk of that. But what becomes increasingly concerning is what happens when houses burn and people are exposed to those chemicals? In many parts of the world, people are burning their trash regularly. I just got back from India, and part of the way they remove garbage is burning whatever happens to be there, and this includes a lot of plastics. These are not just LA concerns.

I also work at the VA with the concerns about burn pit exposures. We have mixed materials in military bases and people exposed to these sorts of things. We're starting to understand toxins, such as trichlorethylene, paraquat, and things that are foundational for what is thought to be a man-made disease of sorts, with Parkinson's disease but also Alzheimer's disease. There was a study that just came out this past year of the Kaiser Permanente cohort of over a million patients records that looked at exposure to different sizes of particulate matter. In wildfires, these particulates tend to be produced very quickly at very high temperatures, with a mix of toxins, as we've talked about. And the densities of these particles are very small -- so small in fact, that they're not usually filtered by the nasal epithelium, and they have a potential way to go right into the brain through the olfactory bulb.

In this cohort of patients that was followed, there was almost a 20% increase in dementia risk per 1 µg/m, which is the way that you measure this particulate matter (PM), below the size of PM. That risk was higher from wildfires than what was seen in the similar particulate matter exposure from other sorts of air pollution, which is already concerning (about a 3% increased risk). We're starting to get data on this and to think about how this affects all of us, with growing numbers of patients who get Alzheimer's disease, and certainly there is the potential link there also with increased risk for Parkinson's disease.

LaFaver: We've become increasingly aware, as you mentioned, of the impact of not only pesticides but also all-around dangerous chemicals; the list is increasing. With that in mind, do you have any tips for people acutely affected by these fires for how they can protect themselves?

Subramanian: Have a way to track air quality with apps and stay indoors if the warnings are higher; if you already have cardiopulmonary disease, definitely be much more vigilant, because it can set off things like asthma attacks. Stay indoors, and keep the windows and doors closed. If you go out, wearing a mask. If you can, wear an N95 or K95 mask; those have been recommended. Additionally, try not to generate more air pollution, so don't burn extra things or use leaf blowers, or burn candles. While the air quality might not be good, perhaps get a HEPA filter, if you can. I've seen some people use a box fan and put in a filter, in a DIY version. Possibly run the air conditioning, which has a HEPA filter.

If you're near the fire, if you can, get away certainly from direct exposure, and don't try to go back and go through things until it's perfectly safe. Use a facial covering, but these particulates can get onto your clothes and into your skin. You can breathe them. You can eat them, if you're eating food in these sort of environments. Just be very mindful, especially in these next few days, where the winds are picking up. These are some practical tips.

Obviously, some of these tips may not be practical for some of our patients whom I already worry may not be connected digitally. Many of them are isolated. Some of the folks who have died are people who could not evacuate, who were not able to quickly mobilize. For so much of this, we rely on digital systems -- smartphones and internet access, which many folks don't have.

LaFaver: I want to switch over to the recent article that you published with Dr Saad in JAMA Neurology on the impact of heat waves. We've mostly talked about the fires so far, but as you mentioned earlier, with climate change and extreme weather conditions becoming more common, heat waves are especially having negative effects. Can you talk on how to prepare and protect ourselves and vulnerable patients from these issues?

Subramanian: There aren't many data. If you're looking for a research niche to fill and hopefully feel fulfilled, I think this is a good one. We are in integrative medicine, and we want to understand the modifiable risk factors that can help people live better with these diseases? Air pollution, and even your zip code, really define outcome. Ray Dorsey has said that if you want to really change the burden of disease in general in the world, focus on air pollution. It's going to be more impactful than, for example, hypertension or hyperglycemia, which is what a lot of us in medicine tend to focus on.

There's been some studies. For example, there was a study looking at rates of admissions and mortality in a part of the world where the temperature had gone 1 °C over the threshold of 34 °C, or 93 °F, and it increased the admissions and mortality in Parkinson's disease by 10% just with that small change. There are parts of the world that live all year round in heat. If somebody is living at a certain temperature, not expecting a sudden boost in heat, they're not prepared to deal with the acute consequences. What ends up happening sometimes is that our patients are on medications where they may not sense that they are dehydrated. Sometimes they have dysautonomia. They may be on anticholinergic medicines that affect their ability to regulate heat. And with Parkinson's disease, the need to be mobile to get your medications, or to get water or supplies, or to get out of your home puts you at increased risk for heat-related morbidity and mortality.

As many of you know I spend time talking about loneliness, and I was fascinated by a book called Project Unlonely, where they talked about who dies in a heat wave. The people who die in a heat wave are 1) people who are old; 2) people who are sick; 3) people who might have had trauma; 4) people who are already marginalized, be it racially or economically; and 5) folks that are on the wrong side of the digital divide -- those who may not have access to all the information and alerts.

That's nearly all of my patients. Many of us have patients like these in our offices and clinics. These are the folks at the highest risk for becoming isolated and lonely and not having touch points to help save them. We as neurologists may know a handful of those patients in each of our practices. Perhaps you should keep a list of those phone numbers and try to check in: Hey, Mr. Smith, there's a heat wave coming our way or a fire coming your way. Are you okay? Do you have somewhere to go, or can you get emergency supplies so you can stay indoors? That's one way we can protect our populations at risk with neurodegenerative disease.

In the paper, we put some practical suggestions for preparing in advance, such as setting alerts when the temperature goes above a certain amount or the air quality changes a certain amount. Maybe prepare the week ahead by storing food, storing water, and maintaining a clean water supply. Make sure that your air conditioning is working. Is there a cooling center you can go to, be it at a mall, or somewhere in your city that you could evacuate to? Then, on the day, make sure that you're not going out in the sun; you're staying indoors. You're staying in contact with close friends and family. Someone's checking on you. If you start to feel lightheaded or dizzy, have a way to alert folks and have access to your medicine, which is huge. I was standing in the pharmacy the other day, and people affected by the wildfires were coming in to get basic medicines and supplies. As doctors, we don't have an easy way to know who needs those backup supplies, and the pharmacists are really overwhelmed.

LaFaver: I really like the suggestion of checking in on vulnerable patients. That reminds me of the early days of the COVID pandemic, because at the time, the social worker at our clinic in Chicago did that.

I really appreciate the time you've taken out of this very stressful week, given what you're going through acutely. A lot of the solutions we talked really need to be done on a political and societal level. You mentioned that Dr Ray Dorsey and Dr Michael Okun are leading the way and will hopefully make some positive changes.

Subramanian: Two final points. We as clinicians are part of the frontline workforce, but don't forget to take time for yourself. Take time for your family. We're all living through this trauma and trying to process this in real time. Even if you haven't been directly affected, try to support each other emotionally and physically on the ground.

Number two, I want to shout out those frontline workers. such as the firefighters who are flying in from all over to be here on the ground in LA, sleeping in tents next to these fires, trying to help us. The occupational risk for some of these frontline workers, like the folks who helped in 9/11, is quite scary if you think about the long-term exposures. I want to thank them for their heroism and bravery. And thank you to Medscape for allowing us to highlight this important topic.

LaFaver: Absolutely. There's acute and longer impacts, and people need to be monitored for sequelae.

Thank you, everyone. I hope this was timely and helpful information, and with that I wish everyone all the best in the days and weeks to come.