Neurotoxicity is defined as toxicity within the nervous system that stems from exposure to substances known as neurotoxins. These neurotoxins affect nervous system function, and can be associated with brain damage. People who have been harmed by neurotoxicity can exhibit a wide variety of symptoms including, but not limited to, problems with memory, concentration, anxiety, depression, personality changes, and confusion. Most of these symptoms are also symptoms of psychiatric disorders.
The connection between environmental and chemical toxins and these psychiatric symptoms is not new – it has been described in medical literature as early as 1850. In a 2016 Psychiatric Times Special Report on Neurotoxicity, there is discussion of various neurotoxins and their potential effects. The report is not an exhaustive coverage of neurotoxins, but rather focuses on a few specific ones and the illnesses they are connected to:
- Methamphetamine Neurotoxicity – Whether used legally (for ADHD for example) or illegally (ecstasy adulterated with methamphetamine), methamphetamines can have both short-term and long-term devastating effects. Some short-term effects include, but are not limited to, hyperactivity, loss of appetite, and restlessness, with higher doses leading to agitation, anxiety, auditory hallucinations and violent behavior. Some long-term effects include but are not limited to cognitive impairment, anxiety, depression, violent behavior, and psychosis. Methamphetamines are also categorized as an “emerging contaminant” of water, which means they have been found in the environment, specifically surface water.
- Chemical Neurotoxicity – We are routinely exposed to chemicals in our daily lives. From the report: “The sources of these exposures are as varied as the chemicals themselves: pesticides on produce, flame retardant compounds on furniture, metals in drinking water, and various chemicals used to manufacture consumer products that have simplified our lives. Research on the impact of these chemicals has highlighted several neurological targets that are disturbed. These findings are further supported through population based studies that have established some chemicals as significant risk factors for neurological deficits.”
- Food Neurotoxicity – Neurotoxins and additives in our food affect us. The report focuses on the influence of diet on ADHD, citing the fact that research has consistently shown that restriction/elimination diets may be effective in reducing symptoms of the disorder. In particular, diets free of processed foods containing additives, particularly colorings and preservatives, may improve symptoms.
- Environmental Neurotoxicity – Environmental toxin exposure, including exposures to heavy metals, polychlorinated biphenyls, biphenol A, and organophophates pesticides, has been associated with symptoms of autism spectrum disorder. There is even mention of a possible connection between the use of Ayurvedic herbs and autism. Lead, in particular, is reported to be a contributor to ADHD and other pediatric psychiatric problems.
Delving into the causes and subsequent development of neuropsychiatric disorders is a complex task, to say the least, and while we still have so much to learn, we cannot discount the very real effects of neurotoxicity on psychiatric disorders. Scientists are continuing their research into the causes, effective diagnoses, and proper treatment of these disorders, focusing not only on endogenous (internal) factors, but on the growing number of exogenous (external) determinants as well.