In the 1950s, the refrigerator mother theory emerged as an explanation for autism. The hypothesis was based on the idea that autistic behaviors stem from the emotional frigidity, lack of warmth, and cold, distant, rejecting demeanor of a childs mother. Parents of children with an ASD experienced blame, guilt, and self-doubt, especially as the theory was embraced by the medical establishment and went largely unchallenged into the mid-1960s. The "refrigerator mother" theory has since continued to be refuted in scientific literature, including a 2015 systematic review which showed no association between caregiver interaction and language outcomes in ASD. Another controversial claim suggested that watching extensive amounts of television may cause autism. This hypothesis was largely based on research suggesting that the increasing rates of autism in the 1970s and 1980s were linked to the growth of cable television at this time. Terminology and distinction from schizophrenia
As late as the mid-1970s there was little evidence of a genetic role in autism, however by 2007 it was recognised as one of the most heritable psychiatric conditions. Although the rise of parent organizations and the destigmatization of childhood ASD have affected how ASD is viewed, parents continue to feel social stigma in situations where their childs autistic behavior is perceived negatively, and many primary care physicians and medical specialists express beliefs consistent with outdated autism research.It took until 1980 for the DSM-III to differentiate autism from childhood schizophrenia. In 1987, the DSM-III-R provided a checklist for diagnosing autism.
Neuropathology
Listed below are some characteristic findings in ASD brains on molecular and cellular levels regardless of the specific genetic variation or mutation contributing to autism in a particular individual:

Limbic system with smaller neurons that are more densely packed together. Given that the limbic system is the main center of emotions and memory in the human brain, this observation may explain social impairment in ASD. Fewer and smaller Purkinje neurons in the cerebellum. New research suggest a role of the cerebellum in emotional processing and language. Increased number of astrocytes and microglia in the cerebral cortex. These cells provide metabolic and functional support to neurons and act as immune cells in the nervous system, respectively. Increased brain size in early childhood causing macrocephaly in 15–20% of ASD individuals. The brain size however normalizes by mid-childhood. This variation in brain size in not uniform in the ASD brain with some parts like the frontal and temporal lobes being larger, some like the parietal and occipital lobes being normal sized, and some like cerebellar vermis, corpus callosum, and basal ganglia being smaller than neurotypical individuals. Cell adhesion molecules that are essential to formation and maintenance of connections between neurons, neuroligins found on postsynaptic neurons that bind presynaptic cell adhesion molecules, and proteins that anchor cell adhesion molecules to neurons are all found to be mutated in ASD. Gut-immune-brain axis
46% to 84% of autistic individuals have GI-related problems like reflux, diarrhea, constipation, inflammatory bowel disease, and food allergies.