Divorce and ADD- connection?

Children that come from divorced families are twice as likely to be prescribed attention-deficit disorder medication, than children whose parents are still married. Of the children with married parents, only 3.3% were prescribed Ritalin.
From divorced families, 6% of 633 kids received this treatment, according to a Canadian study. This study began in 1994, with 4,700 families with children, and parents who were not yet divorced. Then, these families were frequently checked up on, to record the status of their marriages, and what their children were being prescribed.
Researchers aren't yet sure why children of single parents are more likely to receive medication like Ritalin, and other mood altering drugs. But, there is definately some connection here, don't you think?