Are neurological diseases increasing around the world? Yes and no, according to a report published by The Lancet in 2024 on the global burden of nervous system diseases between 1990 and 2021.
About 3 billion — a third of the world’s people — suffer from some nervous system condition. These diseases cause 11 million deaths and 443 million disability-adjusted life years (DALYs), which are a measure of the years lost to illness, disability or early death. Neurological disorders are now the world’s largest source of disability.
The Lancet report does not include an analysis of the role of pesticides in the burden of neurological disease worldwide, although environmental health research continues to expand the evidence that pesticide exposure is a major contributor to that burden.
The Lancet report indicates that DALYs from Parkinson’s disease have increased by 10%, and autism spectrum disorder and dementia by 2% each.
Multiple sclerosis has declined by 1%, according to the report. Importantly, most of the improvement has come from medical interventions, not prevention — in other words, people are living longer with the diseases rather than avoiding them altogether.
But this is not true globally: The burden of disease, and particularly premature death, rests most heavily on the developing world, where medical interventions are much more scarce.
A focus on prevention would be a more equitable approach to the problem. See Beyond Pesticides’ deep archive of the evidence on pesticides and neurological diseases in “Pesticide-Induced Diseases: Brain and Nervous System Disorders” section. Our Gateway on Pesticide Hazards is also invaluable for information about specific pesticides and their adverse health effects.
The Lancet’s big picture does not demonstrate that the burden of pesticide-induced neurological disease is declining.
Such a decline seems a logical impossibility, given that more and more people are chronically exposed to more and more pesticides, and more and more research is establishing both population-level and mechanistic evidence of pesticides’ influence on disease induction and outcome, including neurological disorders.
A recent review by Chinese researchers demonstrates that there is no category of pesticide — not herbicides, not fungicides and not insecticides — that does not contribute to neurological dysfunction. The authors recite numerous examples: the herbicide glyphosate affects both cognitive and motor functions.
The fungicides tebuconazole and azoxystrobin are associated with neurodevelopmental and neurodegenerative disorders. Organophosphate insecticides lead to sensory disruption, emotional disturbances and neurodevelopmental problems.
Several “natural” chemicals, including rotenone and the plant growth regulators gibberellic acid and indole-3-butyric acid, affect the expression of some neurologically relevant enzymes. One research group found that the insect repellent DEET applied to rats’ skin killed their neurons.
The review examines studies showing pesticides’ neurological damage relevant to long-term exposures, rather than the usual acute exposures that form the outdated regulatory toxicological approach to pesticide hazards and risks.
Hellbound and Down 