Language and reading impairments are associated with increased prevalence of non-right-handedness.
Abbondanza F., Dale PS., Wang CA., Hayiou-Thomas ME., Toseeb U., Koomar TS., Wigg KG., Feng Y., Price KM., Kerr EN., Guger SL., Lovett MW., Strug LJ., van Bergen E., Dolan CV., Tomblin JB., Moll K., Schulte-Körne G., Neuhoff N., Warnke A., Fisher SE., Barr CL., Michaelson JJ., Boomsma DI., Snowling MJ., Hulme C., Whitehouse AJO., Pennell CE., Newbury DF., Stein J., Talcott JB., Bishop DVM., Paracchini S.
Handedness has been studied for association with language-related disorders because of its link with language hemispheric dominance. No clear pattern has emerged, possibly because of small samples, publication bias, and heterogeneous criteria across studies. Non-right-handedness (NRH) frequency was assessed in N = 2503 cases with reading and/or language impairment and N = 4316 sex-matched controls identified from 10 distinct cohorts (age range 6-19 years old; European ethnicity) using a priori set criteria. A meta-analysis (Ncases = 1994) showed elevated NRH % in individuals with language/reading impairment compared with controls (OR = 1.21, CI = 1.06-1.39, p = .01). The association between reading/language impairments and NRH could result from shared pathways underlying brain lateralization, handedness, and cognitive functions.