In what ways does lead damage the brain?

Exposure to lead wreaks havoc in the brain, with consequences that include lower IQ and reduced potential for learning. But the precise mechanism by which lead alters nerve cells in the brain has largely remained unknown. Lead affects a growth factor , BDNF, modifying its transport. The researchers also explored how lead curbs production of BDNF in the cell nucleus. One factor, they say, may be a protein called methyl CpG binding protein 2, or MeCP2, which has been linked with RETT syndrome and autism spectrum disorders and acts to "silence" BDNF gene transcription.