A study conducted in children and young adults in Mexico City has shown the presence of combustion-derived nanoparticles in samples of brain tissue obtained at autopsy and cerebrospinal fluid sampled during medical procedures, with those from Mexico City having higher concentrations than those in other, smaller less polluted, cities in Mexico.
Although ‘natural’ magnetite particles can be present in normal brain tissue, spherical particles, in this case ~ 30 nm in diameter and making up 85% of the magnetite particles detected, indicate an external origin, in this case most likely from vehicle exhaust. TEM images of brain tissue with high concentrations of nanoparticles showed extensive cell damage. Markers of cognitive function such as memory, attention span and IQ were all lower in exposed cases, and problems with taste and smell, one of the early symptoms of dementia, were also recorded in young people. However, the presence of these particles in the brain in young people does not yet mechanistically prove a causal role in Alzheimer’s disease causation or progression in later life.