5.4 Section summary
Twin and family studies provide strong evidence for genetic influences in ASDs, and for a spectrum ranging from classic autism to subtle borderline symptoms.
One model linking genetic influences to organic dysfunction sees genetic influences as triggering a single causal chain; another suggests that organic dysfunction may occur independently and add to or interact with genetic vulnerability.
Evidence for brain and neuronal dysfunction ranges from non-specific EEG findings to neuropsychological and fMRI data highlighting specific brain areas, including the frontal and temporal lobes, cerebellum, limbic system and amygdala.
The amygdala model of autism suggests links between findings at biological and socio-cognitive levels, but is currently speculative.
Impaired social interactions between the infant and his/her caregiver may have a detrimental effect on organic functioning.