The medical term used to describe neurological damage caused by exposure to natural or manufactured toxins is neurotoxicity. This condition may result in a wide spectrum of neurological problems from mild symptoms to life-threatening health issues.
In other words, neurotoxicity occurs when certain toxic substances cause damage to parts of the nervous system, including the brain, spinal cord, and nerves. While this condition may occur due to exposure to large amounts of medicines, it may also happen due to some neurotoxic substances at all doses (such as lead).
Moreover, neurotoxicity may also occur during fetal development, childhood development, or adulthood. Commonly, the severity of neurotoxicity depends on when it occurs. Additionally, people with hyperbilirubinemia (jaundice) and Charcot-Marie-Tooth disease (CMT) are more likely to develop neurotoxicity.
In general, it is difficult to estimate how many people experience this condition because there are a lot of neurotoxicants, and people experience different symptoms. However, according to some research, there are about 385 million cases of unintended and acute (sudden and severe) pesticide poisoning each year in the whole world. In addition, approximately 1 million people die from lead poisoning, and about 1 in 3 children have increased levels of lead in their blood.
Neurotoxicants
In general, there are hundreds of neurotoxicants that can come in gas, liquid, or solid form. Sometimes, even a single exposure to them may cause symptoms. Check some examples of neurotoxicants below:
- Heavy metals (such as mercury, lead, and others)
- Other natural substances (including carbon monoxide, arsenic, trichothecene mycotoxins, and others)
- Pesticides (including chlorpyrifos, organophosphates, and others)
- Industrial or cleaning solvents (such as tetrachloroethylene)
- Certain manufacturing materials – These include vinyl chloride, toluene, formaldehyde, and polybrominated diphenyl ethers (PBDEs)
- Other substances, including amphetamines, opioids, inhalants, cocaine, and alcohol.
Moreover, EDCs (endocrine-disrupting chemicals), such as bisphenol A (BPA), phthalates, and polychlorinated biphenyl compounds (PCBs), may also cause neurotoxicity but indirectly.
Medicines
There are many medications that may cause neurotoxicity, especially if they are used for long periods or in high doses. These include antipsychotics, antibiotics, and others. However, there are some cancer-related therapies that usually cause neurotoxic effects. Check some examples below:
- Taxanes (such as Paclitaxel, Docetaxel, and others)
- Platinum-based agents (Oxaliplatin, Cisplatin, Carboplatin, and others)
- Vinca alkaloids (such as Vincristine, Vinblastine, and others)
- Proteasome inhibitors
- Thalidomide analogs
In some cases, people may develop neurotoxicity due to radiation therapy (a cancer treatment) that causes damage to the nervous system.
Symptoms
Usually, people with neurotoxicity experience different symptoms. It often depends on some factors, including age, overall health, and the type of neurotoxicant. Check some physical symptoms of neurotoxicity below:
- Appetite changes
- Diarrhea
- Extreme tiredness (fatigue)
- Coordination and balance problems
- Headaches
- Muscle problems, including weakness, twitching, or spasms
- Nausea
- Vomiting
- Numbness
- Sleep changes (such as insomnia)
- Pain disorders (including neuropathic pain)
- Dysarthria (speaking problems)
- Vision changes (such as vision loss)
However, people with neurotoxicity may also experience some cognitive symptoms. Examples include:
- Behavioral changes
- Executive dysfunction (such as difficulty regulating emotions and problems with attention and focus)
- Dizziness
- Disorientation
- Increased aggression
- Memory problems
- Mood swings
- Cognitive decline (including mild cognitive impairment)
Immediately contact your healthcare professional if you or your child experiences any of the previous symptoms. Otherwise, it may lead to permanent damage to a part of the nervous system.
Emergency Symptoms
Call 911 or go to the nearest emergency room (ER) immediately if any of the following symptoms occur. For example:
- Irregular heart rhythm (arrhythmia)
- Confusion
- Loss of consciousness
- Psychosis (including hallucinations)
- Seizures
- Hyperthermia or hypothermia
- Sudden and severe muscle weakness
- Vision problems that occur suddenly
- Breathing problems
Causes
This condition occurs when you are exposed to neurotoxicants that cause damage, changes, or destroy cells in the peripheral and central nervous system. In most cases, they negatively affect the neurons (nerve cells) that are vital for transmitting and processing signals between the brain and the rest of the body. Furthermore, neurotoxicants may also cause damage to the myelin, which is the protective layer of the nerves. Usually, neurotoxicity damage can be seen in the following ways. Check some of them below:
- Changes in neurotransmitter (such as Dopamine) levels and signaling
- Inflamed brain or spinal cord (neuroinflammation)
- Structural changes of the brain (such as differences in gray and white matter volume)
- Damage to the protective layer of the nerves (myelin)
How Neurotoxicants Enter the Body?
Neurotoxicants often enter the body by breathing or consuming (eating or drinking) them, or through skin absorption. However, these neurotoxicants may negatively affect the developing baby if you are pregnant. When they enter the bloodstream the travel to the fetus through the umbilical cord.
Furthermore, when these neurotoxicants enter the bloodstream, they may cross the blood-brain barrier (BBB) and cause damage to parts of the nervous system. Sometimes, they can indirectly affect the brain and other body systems (such as EDCs). Check below some places where toxins are often found:
- Environmental sources (including traffic, farming, and industrial activities)
- Parks, schools, or during local chemical spills
- Certain household products or foods
What Are The Potential Complications of Neurotoxicity?
Those who develop this condition may also experience some complications, such as chronic neurological problems or even death in more severe cases. Check for other complications of neurotoxicity below:
- ADHD (attention-deficit/hyperactivity disorder)
- Learning disabilities
- Major depressive disorder
- Anxiety
- Schizophrenia
- Autism spectrum disorder (ASD)
- Permanent cognitive decline
- Memory loss
- Coma
This article does not contain a full list of complications, but you can consult with your healthcare professional about measures to reduce the risk or even prevent them. In addition, there is a connection between neurotoxicants and previous mental health conditions, but more research is needed to confirm if neurotoxicity directly causes them or not.
How to Prevent Neurotoxicity?
In general, it is not possible to prevent this condition because you cannot prevent all exposure to neurotoxicants. However, you can take some steps to reduce the risk. For example:
- Get a carbon monoxide detector in your home and change batteries every year
- Do not mix cleaning products or household chemicals
- Test your home for harmful toxins (such as lead)
- When the air quality is bad, you should keep the windows closed
- Avoid recreational medicines
You should know that preventing exposure to neurotoxicants is not just your responsibility, but it is a collective responsibility of federal and local governments, corporations, and citizens. For instance, NIEHS (National Institute of Environmental Health Services) is continuously studying how environmental neurotoxicants affect human health.
Diagnosis
Doctors often begin the diagnosis with a physical examination and questions about your symptoms and medical history. However, to confirm this condition, they may also perform a neurological examination and the following tests and procedures. Examples include:
- Behavioral assessment
- Eye examination
- Electroencephalogram (EEG)
- Cognitive tests
- Imaging tests, such as a brain MRI (magnetic resonance imaging) scan
- Nerve conduction study
- Electromyography (EMG)
- Blood tests
- Spinal tap (also known as a lumbar puncture)
- Neuropsychological testing and assessment
Treatment
The treatment for people with neurotoxicity is often different because it depends on several factors. These include the type of neurotoxins, the severity of neurotoxicity, existing health problems, age, and preferences. In general, the treatment goal is to relieve the symptoms, prevent life-threatening complications, and improve your quality of life.
Frequently Asked Questions
What is the prognosis for someone with neurotoxicity?
Usually, the prognosis varies among people because it depends on the following factors. For example, the amount and length of exposure, the type of neurotoxin, the extent of the nervous system damage, age, overall health, and others. For more details, discuss it with your doctor.
What are the symptoms of neurotoxicity?
Commonly, people who develop neurotoxicity experience the following symptoms. For example, headaches, extreme tiredness, memory problems, mood swings, tingling, seizures, paralysis, vision loss, confusion, and coma (in more severe cases). If any of the previous symptoms occur, immediately go to the nearest emergency room (ER) or call 911.
What drugs cause neurotoxicity?
Prolonged or high doses of the following medicines may cause this condition. These include chemotherapy agents (including platinum compounds, taxanes, and others), illicit substances, some antibiotics (such as aminoglycosides), immunosuppressants, and certain heavy metals (including mercury and lead). If you have any other questions, ask your healthcare provider.
