Hemispheric asymmetries and early infantile autism.
Left-brain damage is too simple an answer for autism language woes.
01Research in Context
What this study did
The author read every paper he could find on brain sides and autism. He asked: does damage to the left side explain the language problems we see?
He looked at handedness reports, brain scans, and autopsy work. The review covered kids with early infantile autism.
What they found
No. A simple left-brain injury story does not fit the data. Language trouble in autism needs a more careful explanation.
The old idea that all autistic kids are left-side broken was too neat.
How this fits with other research
Blanchard et al. (1979) came first. They saw more right-wider-than-left back-brain asymmetry in autistic kids and blamed left-side faults. McCann (1981) used their case series as a foil and said the picture is messier.
Faso et al. (2016) later pooled imaging data and moved the field forward. They showed right-side language patches pop up only when the task is hard. Their meta-analysis replaces the old guess-work with numbers.
Rysstad et al. (2016) also extended the story. They counted hands and proved non-right-handedness really is more common in autism, something the 1981 review doubted as crude evidence.
Why it matters
Do not assume one broken side causes language delay in autism. Use current imaging or at least check both hands. When you see mixed dominance, plan teaching that taps both sides: visual cues, gestures, and spoken words together. Keep watching new brain-coupling studies; they are already shaping early biomarkers and targeted language plans.
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02At a glance
03Original abstract
The observation that language disorders constitute a major symptom of early infantile autism has led some researchers to speculate that the autistic syndrome may be a result of brain damage to the left hemisphere. Such speculation has fostered a number of studies in which attempts have been made to link autism with ostensibly positive signs of left hemisphere damage, such as left-handedness and preferences for "right hemisphere" functional and cognitive activities. In the present review, contributions to this area are systematically reviewed. Studies attempting to demonstrate that an unusually high incidence of left-handedness occurs in autistic samples are examined. Functional and morphological studies examining patterns of asymmetry in autistic samples are reviewed. It is shown that most studies on handedness fail to account adequately for the role that age of subjects may play in the manifestation of left-handedness. A simple cause-and-effect model of abnormal cerebral asymmetry and autism is rejected in favor of a more integrative yet parsimonious model that specifically attempts to explain the language disorder common to autism.
Journal of autism and developmental disorders, 1981 · doi:10.1007/BF01531615