By Carter Trent
EDITOR’S SUMMARY: The escalating global burden of neurological disorders demands immediate attention. Mounting evidence shows that environmental toxins, ultra-processed diets, inactivity, poor sleep, and chronic stress are reshaping brain health worldwide. By making deliberate changes—choosing brain-supportive foods, improving air quality, limiting plastic use, and weaving more movement and play into daily life—you can actively protect your cognitive future.
The shadow of disease has followed humanity through the ages—from the Black Death and smallpox to the Spanish Flu. Now, another insidious threat grips the globe. Neurological disorders have quietly climbed to become the leading cause of disability and the second leading cause of death worldwide. According to the World Health Organization, one in three people are now affected—and the trend is accelerating. Since 1990, cases have risen by nearly 20 percent. Defined by their impact on the nervous system, neurological disorders include conditions such as stroke, Alzheimer’s disease and other dementias, Parkinson’s disease, autism, and multiple sclerosis. The brain, spinal cord, and nerves form the core of this system, coordinating every action, thought, and sensation in your body. When that network is disrupted, the consequences can be devastating to your quality of life.
Alzheimer’s disease—the most common form of dementia and the seventh leading cause of death in the U.S.—attacks the brain by destroying neurons, the cells that transmit signals between your brain and body. These signals enable everyday functions like speaking and moving. As the disease progresses, the brain shrinks, gradually erasing memories and impairing your ability to manage routine tasks, such as paying bills or finding your way home. You may lose the ability to recognize loved ones, communicate, or care for yourself—slowly becoming a fragment of your former self. Given how profoundly neurological diseases affect daily life, their rising incidence is deeply concerning. This rise stems from a range of factors tied to human activity and the industrialization of modern society.
Understanding the Surge
What you breathe reaches your brain
One major contributor is air pollution—specifically fine particulate matter known as PM2.5. These microscopic particles measure less than 2.5 micrometers in diameter, about 36 times smaller than a grain of sand. PM2.5 is released into the air from sources such as industrial manufacturing, power plants, and vehicle emissions. Because it’s so small, this particulate matter can enter your bloodstream and cross the blood-brain barrier—a protective membrane that normally blocks harmful substances from reaching the brain, but not particles this minuscule. Once inside the brain, this pollutant triggers inflammation and damages neurons through oxidative stress—a process that produces unstable molecules called free radicals. Over time, the cumulative damage can contribute to the development of neurological pathology.
Exhaust from cars and airplanes accelerates disease progression by pumping PM2.5 into the air you breathe. The number of vehicles on the road has climbed steadily over the past 30 years—rising nearly 50 percent since 1990. Airplane emissions dipped during the COVID-19 pandemic but are rising again—and are projected to surpass pre-pandemic levels in the coming years. A 2020 study published in The Lancet, “Long-term effects of PM2·5 on neurological disorders in the American Medicare population: a longitudinal cohort study,” found a clear correlation between increased PM2.5 exposure and higher rates of Alzheimer’s and Parkinson’s disease. The researchers wrote:
“Our study provides strong epidemiological evidence that long-term exposure to air pollution is significantly associated with a higher risk of neurological health deterioration, even at concentrations less than the current national standards.”
Research published in Science of the Total Environment—a systematic review and meta-analysis titled “The association between PM2.5 exposure and neurological disorders”—found that long-term exposure to PM2.5 significantly increases the risk of developing various neurological conditions, including stroke and autism. The authors emphasized that the higher your cumulative exposure, the greater your risk. In their words:
“The results from our study suggest that PM2.5 exposure is associated with a wide spectrum of neurological disorders, and that incidence and mortality are significantly influenced by mean PM2.5 concentration and the duration of exposure, in which PM2.5 exposure increases risks of stroke, dementia, Alzheimer’s disease, ASD (autism spectrum disorder), Parkinson’s disease.”
Tiny plastics, lasting consequences
Alongside air pollution, microplastics are a human-made pollutant contributing to the rise in neurological disorders. These tiny plastic fragments measure less than five millimeters—about one-fifth of an inch—in length. Because these particles are so small, they can infiltrate your body—and have been found in brain tissue, the heart, and the stomach. Society’s widespread use of plastic has led to an increase in microplastics, with items like disposable utensils, water bottles, and bags breaking down into tiny fragments. Plastic doesn’t decompose; it simply fractures into smaller pieces over time. Wind and rain then disperse these particles across land and into water supplies. Scientists estimate you now consume the equivalent of one credit card’s worth of microplastics each week—a number that continues to climb. Between 10 and 40 million metric tons are released into the environment annually, and that amount is projected to double by 2040 due to skyrocketing plastic production. As a result, your exposure will only intensify.
A 2024 research paper from Toxicology, “Microplastics/nanoplastics and neurological health: An overview of neurological defects and mechanisms,” examining the neurological effects of microplastics found that prolonged exposure is toxic to the nervous system. Mice that ingested microplastics for just one week showed progressive neuron loss—mirroring the neurodegeneration seen in Alzheimer’s and Parkinson’s diseases.
From Nature Medicine, a 2025 study titled “Bioaccumulation of microplastics in decedent human brains” analyzed brain tissue from individuals who died between 2016 and 2024. The findings revealed an alarming trend: brains from 2024 contained 50 percent more microplastics than those from 2016, signaling rising exposure. Levels in the brain were also 7 to 30 times higher than in other organs—with the greatest concentrations found in individuals who had dementia. The exact reason remains unclear, but scientists have a theory: microplastics tend to bind to fats called lipids, which are essential to neuron function. As a result, they may preferentially accumulate in the brain.
How you live shapes how your mind works
Environmental pollution isn’t the only factor driving the rise in neurological decline—lifestyle choices play a major role, too. These include your diet, physical activity, stress levels, and sleep patterns. For example, research shows that eating ultra-processed foods—common in the standard American diet (SAD)—raises the risk of cognitive impairment, which affects mental abilities such as memory, learning, reasoning, and decision-making. Foods such as refined-grain cereal, chips, packaged snacks, and frozen meals fall into this category. According to Frank Hu, chair of the Department of Nutrition at the Harvard T.H. Chan School of Public Health, “The vast majority of [ultra-processed foods] are unhealthy, and the more of them you eat, the higher your risk of various diseases.”
A 2021 study published in Ageing Research Reviews, titled “Western diet as a trigger of Alzheimer’s disease: From metabolic syndrome and systemic inflammation to neuroinflammation and neurodegeneration,” explored how SAD may contribute to Alzheimer’s disease. The researchers identified key mechanisms, including obesity and disruptions in the gut microbiome. Carrying extra weight disrupts your body’s metabolic function and contributes to structural deterioration in the brain, raising your risk of cognitive decline and Alzheimer’s disease by as much as sixfold.
Consuming a Western diet often leads to weight gain—reflected in the fact that an estimated 74 percent of American adults are overweight or obese, according to the U.S. Centers for Disease Control and Prevention. The standard American diet also alters the gut microbiota. Because the gut and brain are closely connected, disruptions in gut microbes can weaken the blood-brain barrier. This allows toxins to enter the brain, triggering chronic neuroinflammation that compounds other SAD-related effects like metabolic dysfunction. Together, these factors contribute to the cognitive deterioration that can ultimately lead to Alzheimer’s disease.
Adding to the risks posed by SAD-centered eating is a lack of physical activity. Americans today lead more sedentary lives than at any point in history—a trend reflected in the 83 percent increase in sedentary jobs since 1950. This rise in prolonged inactivity has contributed to the increasing prevalence of neurological conditions. Physical stagnation not only promotes weight gain—it also reduces blood flow to the brain, limiting the oxygen and nutrients needed for healthy function. In 2018, UCLA researchers found that low daily movement was linked to shrinkage in the medial temporal lobe, the part of the brain responsible for forming new memories. This finding was reinforced by a 2025 study, which went further—showing that even with regular exercise, prolonged sitting still increases the risk of dementia due to loss of brain volume.
Neurologist Angela Jefferson, a co-author of the 2025 study, emphasized the importance of breaking up sedentary time: “It is critical to our brain health to take breaks from sitting throughout the day and move around to increase our active time.” How much sitting is too much? A team from UC San Diego discovered in 2024 that sitting more than 11 hours a day is associated with a 57 percent higher risk of death compared to those who sit less than 9.5 hours. The takeaway: exercise alone isn’t enough—your brain needs regular movement woven throughout your day.
Compounding the dangers of a poor diet and lack of physical activity is another widespread issue: insufficient sleep. According to a Gallup survey, nearly 60 percent of Americans aren’t getting enough rest. Sleep deprivation disrupts circadian rhythms and increases the risk of neurological disease. Circadian rhythms are 24-hour biological cycles that regulate essential functions such as gene expression, hormone release, digestion, and temperature. When these rhythms fall out of sync, the effects go beyond fatigue—research suggests they may play a role in triggering neurological decline.
Once circadian rhythms are thrown off, sleep becomes more fragmented—and the resulting neurological changes can further disrupt sleep patterns, creating a self-reinforcing cycle. Breaking that loop starts with consistency: maintaining a regular bedtime is one of the most effective ways to stabilize circadian rhythms and support long-term brain health. That means going to bed and waking up at the same time each day—even on weekends—getting at least 15 minutes of sunlight first thing in the morning, limiting exposure to artificial light at night, and creating a calming wind-down routine to signal to your body that it’s time to rest.
Rising stress is a powerful driver of neurological disorders. High tension activates your body’s fight-flight-freeze response. When pressure becomes chronic, the brain stays in a constant state of alert, fueling inflammation and gradually impairing its ability to function. Studies show that ongoing stress kills neurons and shrinks the prefrontal cortex—the region responsible for memory and learning. As this damage accumulates, the risk of developing neurological disease increases. Today, nearly half of Americans report feeling chronic stress—the highest level in 30 years.
Beyond structural damage, chronic stress also disrupts the brain’s delicate chemical balance. Elevated cortisol levels interfere with neurotransmitters like serotonin and dopamine, which are essential for mood regulation, focus, and motivation. Over time, this biochemical strain can weaken the hippocampus—a structure critical for forming new memories—and impair communication between brain regions. Stress doesn’t just affect your mental state in the moment; it rewires neural circuits in ways that make it harder to recover from future challenges, creating a cycle that can accelerate neurological decline.
Medication use is another factor that can contribute to neurological decline. In 2025, National Geographic reported on research highlighting the dangers of diphenhydramine, the active ingredient in many popular over-the-counter drugs, including Benadryl and Tylenol PM. It’s commonly found in cold and allergy medications, as well as sleep aids. Long-term use has been linked to a higher risk of developing dementia and other neurodegenerative conditions. Diphenhydramine is especially dangerous for children and older adults—so much so that several European countries are now restricting its use. Emerging research underscores the importance of understanding the side effects of any medication you take, even those sold over the counter. In 2025, the World Allergy Organization Journal called for the drug’s discontinuation, stating:
“Based on a comprehensive evaluation of practice patterns and the prevalence and incidence of adverse clinical events, we believe that diphenhydramine has reached the end of its life cycle, and in its class of therapies it is a relatively greater public health hazard. We recommend it should no longer be widely prescribed or continue to be readily available over the counter.”
Diphenhydramine is not the only pharmaceutical associated with neurological risk. Anticholinergic drugs—a category that includes certain antihistamines, antidepressants, and bladder control medications—can cause memory loss, confusion, and increase the risk of dementia, particularly with long-term use. These medications block acetylcholine, a neurotransmitter critical for learning and memory. While they may offer temporary symptom relief, the neurological trade-off can be significant. This growing body of research highlights the importance of asking questions about all medications—prescription or otherwise—and weighing short-term benefits against long-term cognitive costs. Older adults are especially vulnerable to the neurological side effects of medications due to changes in how the body processes drugs with age. As Harvard Health explains:
“Many drugs have a stronger effect on older people than younger people. With age, the kidneys and liver clear drugs more slowly, so drug levels in the blood remain higher for a longer time. People also gain fat and lose muscle mass with age, both of which change the way that drugs are distributed to and broken down in body tissues. In addition, older people tend to take more prescription and over-the-counter medications, each of which has the potential to suppress or enhance the effectiveness of the others.”
You Have More Influence Than You Think
There are practical ways to reduce your risk of developing a neurological disorder—starting with your daily habits. Focus on getting consistent sleep, managing stress, and staying physically active. Choose organic food whenever possible to reduce your exposure to pesticides and herbicides—especially for produce on the Environmental Working Group’s “Dirty Dozen” list. Actively lowering your toxic load is only part of the equation; what you add to your diet matters just as much. Opt for brain-supportive foods, especially those rich in healthy fats—such as wild-caught salmon, sardines, walnuts, flaxseeds, chia seeds, avocados, olives, and extra virgin olive oil. These fats help reduce inflammation, support cell membranes, and fuel brain function.
Flavonoid-rich foods offer powerful protection. These plant-based compounds have antioxidant, antiviral, and anticancer properties. A 2021 study published by the American Academy of Neurology, “Adding color to your plate may lower risk of cognitive decline,” found that eating flavonoids daily reduced the risk of cognitive decline by 20 percent. An additional review from the American Journal of Clinical Nutrition found that people who consumed the highest levels of flavonoids had a 50 percent lower risk of developing Alzheimer’s disease. You’ll find them in foods like strawberries, oranges, apples, peppers, onions, and even dark chocolate.
Air pollution is one more area where you can take protective steps. Start by monitoring the U.S. Air Quality Index, a government tool that measures outdoor pollution levels in your area. When air quality is poor, limit time outside and stay indoors as much as possible. Indoors, air quality can also be compromised by cooking fumes, cleaning products, or off-gassing from synthetic materials. Use an air purifier equipped with a HEPA filter to remove harmful particles, including PM2.5. On low-pollution days, open windows to refresh the air inside your home. Tools like AirNow and IQAir make it easy to track your local air quality in real time.
When it comes to microplastics, exposure is inevitable—but you can reduce your long-term risk by limiting how much infiltrates your daily environment. One of the most effective ways is to cut back on plastic use. Choose clothing made from natural fibers like bamboo, organic cotton, wool, linen, and hemp instead of synthetics like polyester or nylon, which shed microplastics during washing. Look for toiletries and cosmetics that are free of plastic and other harmful chemicals. Adopt reusable water bottles and choose food products packaged in glass or other non-plastic materials—think peanut butter, condiments, and drinks in jars. Plastic containers constantly shed microplastics, much like your skin sheds cells, and when they come into contact with food, that exposure ends up in your body.
Caring for your brain isn’t only about reducing harm—it’s also about creating joy. Don’t underestimate the neurological power of play. Unstructured, joyful activities—whether splashing in the ocean, dancing in your living room, or tending a garden—activate brain regions tied to creativity, emotional regulation, and resilience. Research shows play “enhances brain structure and function and promotes executive function.” It also lowers stress hormones, improves cognitive flexibility, and helps form new neural connections. In a society that often prizes productivity over presence, giving yourself permission to be playful is a potent form of brain care.
The specter of neurological disease is deeply unsettling, given how completely it can erode your quality of life. Its growing prevalence reflects how the choices and conditions of modern society are reshaping human biology. The environment, your diet, daily habits, and medications are influencing your brain in profound and lasting ways. Sustaining neurological health depends on a willingness to make informed, intentional choices—from what you eat to how you move and respond to stress. While you can’t control every variable, recognizing the influence of your behavior and surroundings gives you the power to push back—before the damage becomes irreversible.
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Published on September 25, 2025.
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