↑ BDNF in ASD, CDD compared to HC and NNI ↑ anti-BDNF IgM and IgG in autism, CDD and epilepsy compared to HC ↑ IgM to endothelial cells in autism, CDD, PDD-NOS, and epilepsy compared to HC and NNI ↑ IgG to endothelial cells in autism and PDD-NOS compared to HC ↑ IgM and IgG to MBP in autism, CDD, PDD-NOS, and epilepsy compared to both HC and NNI, LKS not elevated. Here, BDNF is linked to pervasive developmental disorder - not otherwise specified.