A spoken language disorder may be a primary disability (SLI) or may exist in conjunction with other disorders and disabilities (e.g., ASD, ADHD, etc.). When a language disorders occurs in conjunction with other disorders and disabilities, the causes are typically defined in terms of these specific conditions. Links to disorder- and condition-specific Practice Portal pages will be included as those pages are developed.
In the case of SLI, the causes are difficult to determine; however, a number of factors have been proposed, including cognitive processing deficits (e.g., Miller, Kail, Leonard, & Tomblin, 2001; Ellis Weismer & Evans, 2002; Leonard et al., 2007), biological differences (e.g., Ellis Weismer, Plante, Jones, & Tomblin, 2005; Galaburda, 1989; Hugdahl et al., 2004), and genetic variations (e.g., Rice, 2012, 2013). These factors may not be independent of one another. For example, a genetic variation might lead to a difference in brain morphology or function that leads to a difference in cognitive processing (Reed, 2012).