Language and reading impairments are associated with increased prevalence of non‐right‐handedness

Abstract

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 (N cases = 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.

Differential Cognitive Effects of Unilateral Subthalamic Nucleus Deep Brain Stimulation for Parkinson's Disease

“…Regarding hemispheric specialization of language, our sample was overwhelmingly right‐handed. While we did not formally evaluate language dominance with functional MRI or an invasive Wada procedure, 95% of right‐handed individuals display left hemisphere language dominance, whereas 70% of left‐handed individuals display left hemisphere dominance, as well 56 . One possibility is that patients with variable degrees of right hemisphere language dominance might be adversely affected by right STN DBS, but inclusion of the small number of left‐handed and ambidextrous participants in our sample did not impact our group‐level findings.…”