We know that lead damages the brain, and that it does so by somehow affecting the release of neurotransmitters at synapses (the process by which neurons pass messages on). Now a new study explains exactly what lead does. Apparently, during the formation of synapses, lead lowers the levels of key proteins involved in neurotransmitter release (synaptophysin and synaptobrevin), and reduces the number of fast-releasing sites. These effects may occur through the inhibition of the NMDA receptor (which produced similar effects), disrupting the release of BDNF. While new synapses are created throughout our lives, there is an explosion of synapse formation during a child's early brain development, explaining why young children’s lead exposure is particularly damaging.
(2010). Lead Exposure during Synaptogenesis Alters Vesicular Proteins and Impairs Vesicular Release: Potential Role of NMDA Receptor-Dependent BDNF Signaling.
Toxicol. Sci.. 116(1), 249 - 263.