Can childhood bullying cause mental illness? I am the proud aunt of four nephews and one niece, all age five and under (family gatherings are very lively). The oldest, Desi, has started preschool; but, as a child with sensory processing disorder, is having a hard time. The other children are mean to him–one said he hated him in front of their mothers and the other boy’s mother did nothing. Desi goes into the playhouse and cries when the other children refuse to play with him. It reminds me of my childhood and breaks my heart to see it played out with my special needs nephew. I fear the answer to the question, “Can childhood bullying cause mental illness?” will play out with him.