Decades after 9/11, toxic dust and post-traumatic stress disorder may be accelerating the aging of first responders’ brains.

Hundreds of first responders have told me that they remember exactly how they felt during the attacks on the World Trade Center, even 25 years later.

They told me they remembered not being able to think, see or smell anything. They could only concentrate on digging and clearing debris from the road.

They could not rest because those trapped under the rubble could not wait. Death was all around them, and they could do everything they could to contain it.

Although what happened on September 11 was unprecedented, tragedies like this happen quite often.

As an occupational therapist working with 9/11 first responders, I can easily imagine the same thoughts among other firefighters, paramedics, and construction workers trying to save lives after the deadly summer 2026 earthquakes in Venezuela, Colombia, and Indonesia, or the catastrophic floods in Nepal.

These first responders may also need to recover human remains from the rubble. These moments of intimate grief are surrounded by dust, toxic fumes and cries for help. And this trauma makes itself felt.

Whether industrial or nuclear disasters, extreme weather, wildfires, volcanic eruptions, war or terrorist attacks, first responders and affected communities can experience significant physical and mental health impacts both during rescue and recovery operations and for years afterwards.

Everyone is vulnerable to mental and physical harm, no matter how well trained they are.

My team’s research shows that these risks include post-traumatic stress disorder, which can lead to faster aging of the brain.

People gather at a reflecting pool during a memorial marking the 25th anniversary of the September 11 attacks on September 11, 2026.

The terrorist attacks of September 11, 2001 killed approximately 3,000 people.

PTSD among first responders

Post-traumatic stress disorder, also known as PTSD, is a complex mental health condition that can develop after experiencing or witnessing a traumatic event.

Psychological trauma is the lasting emotional consequences of direct or indirect exposure to life-threatening circumstances or violence.

PTSD can include intrusive memories, avoidance, hypervigilance, trouble sleeping, and changes in mood and thinking. Anxiety and depression commonly occur along with post-traumatic stress disorder.

About 23 percent of World Trade Center respondents were diagnosed with post-traumatic stress disorder. By comparison, about six percent of the U.S. population will suffer from PTSD in their lifetime.

When I talk to 9/11 first responders, they describe their PTSD and cognitive difficulties as interrelated problems that continue to impact their lives today.

These traumatic memories remain vivid, and some first responders continue to experience anxiety, depression, intrusive thoughts, trouble sleeping, and difficulty regulating their emotions.

Trauma accelerates brain aging

As many 9/11 first responders aged, they also noticed their memory, concentration, and mental acuity decline.

They are increasingly afraid of losing their independence. Physical illness, cognitive changes, and emotional disorders do not occur as separate conditions, but often reinforce each other.

In another study, researchers on my team tracked the cognitive function of more than 5,000 World Trade Center first responders without dementia between 2014 and 2022.

Firefighters make their way through rubble after one of the towers collapsed on September 11, 2001.

Over about five years, 228 people developed dementia before age 65.

First responders who had the most exposure to potentially neurotoxic dust and debris at ground zero had significantly higher rates of dementia than those with minimal exposure or who routinely used personal protective equipment such as respirators.

This association remained after controlling for demographic, lifestyle, medical, and genetic factors.

Before I began studying the health effects of 9/11, I studied workers exposed to neurotoxic metals and industrial pollution in northern Italy.

Knowing about the harmful toxins contained in World Trade Center dust, I began to wonder whether 9/11 survivors might face similar long-term risks to their brains.

That concern grew when brain scans of both groups showed similar increases in deposits of a protein associated with Alzheimer’s disease and cognitive decline called beta-amyloid.

My team’s research also showed that MRI findings on the brains of men who participated in the 9/11 attacks with PTSD were consistent with older-looking brains than those of people without PTSD.

In this 2025 study, we measured brain structures using MRI and an artificial intelligence model to estimate the age of each participant’s brain.

The artificial intelligence model was trained to predict a person’s chronological age based on their overall brain structure, using data from more than 11,500 MRI brain scans of healthy people aged 5 to 95 years.

We used the difference between a person’s predicted brain age and their actual age as a measure of accelerated brain aging.

We also saw that the brains of first responders with PTSD looked about three years older than their chronological age.

In contrast, the estimated brain age of respondents without PTSD roughly matched their actual chronological age.

Each additional month a first responder spent working at ground zero was associated with approximately four to five additional months of apparent brain aging, suggesting that the duration of exposure to the disaster played a key role in this aging process.

A firefighter rests near the destroyed World Trade Center on September 12, 2001 in New York.

An ambulance, covered in debris, burns after the collapse of the first World Trade Center tower on September 11, 2001.

Caring for First Aiders

First responders’ experience shows that the aftermath of 9/11 poses an ongoing public health challenge. These health consequences develop as people age, and decades later they still require coordinated mental, cognitive, physical and social support.

Every anniversary of 9/11 brings back vivid memories of the tragedy, as well as the same anxiety, disappointment and pain of being there.

However, many on the front lines told me that they felt pride and a sense of belonging knowing that they helped people who were in desperate need. Their service remains an enduring example of human solidarity in times of crisis.

Respecting this heritage means protecting those who come to our aid in times of emergency.

This article is adapted from The Conversation, a nonprofit news organization dedicated to sharing expert knowledge. It was written by Roberto Lucchini, professor of occupational and environmental health sciences at Florida International University. It was edited by Alexa Lardieri, health editor of the Daily Mail in the US.