Dyslexic adults in a representative sample of 13,054 adults aged 18 and over in the 2005 Canadian Community Health Survey included 1,020 respondents who reported that they had been physically abused during their childhood and 77 who reported that they had been diagnosed by a health professional with dyslexia. 

That translates to 35 percent of Canadian adults with dyslexia reporting they were physically abused before they turned 18. In contrast, 7 percent of those without dyslexia reported that they had experienced childhood physical abuse. 

"Even after accounting for age, race, sex and other early adversities such as parental addictions, childhood physical abuse was still associated with a six-fold increase in the odds of dyslexia" says coauthor Esme Fuller-Thomson, professor in social work at the University of Toronto. "Our data do not allow us to know the direction of the association. It is possible that for some children, the presence of dyslexia and related learning problems may place them at relatively higher risk for physical abuse, perhaps due to adult frustrations with chronic learning failure" said study co-author, Stephen Hooper, professor of Psychiatry and Pediatrics, and Associate Dean and Chair of Allied Health Sciences at the University of North Carolina School of Medicine. "Alternatively, given the known association between brain dysfunction and maltreatment, it could be that the experience of physical abuse may also contribute to and/or exacerbate such learning problems, secondary to increased neurologic burden.

"Although we do not know if the abuse-dyslexia association is causative, with one-third of adults with dyslexia reporting childhood abuse, it is important that primary health care providers and school-based practitioners working with children with dyslexia screen them for physical abuse."