The main link between autism and MMR/mercury was the timing- that autism symptoms show up around the same time as the vaccine is given. But current research has shown differences in the brain and behavior of autistic babies, such as verbalization and visual contact, way before the age of MMR vaccine, from 6 months and even as young as 3-4 months. Hard to blame something for causing autism when autism is present before that something.
For those who want scientific data supporting the above statement, a quick look at Medline will provide such studies. I can “regurgitate” this since I have an advanced science degree.
For example, (quoted from a review by Sperdin and Schaer, Front Neurosci. 2016 10:393) “Recent functional neuroimaging and electroencephalography studies demonstrate that aberrant voice processing could be a promising marker to identify ASD very early on. With the advent of refined brain imaging methods, coupled with the possibility of screening infants and toddlers, predictive brain function biomarkers are actively being examined and are starting to emerge.”
“In sum, a large body of clinical studies to date point to expressive and receptive language deficits already in the first year of life for young children who will subsequently develop ASD during toddlerhood, suggesting that the neural systems responsible for orienting to and processing human vocalizations are altered very early on.”
“Wolff and collegues observed abnormalities in white matter fiber tracts in infants at risk (at 6 months) and who were diagnosed at 24 months (Wolff et al., 2012). In a recent study of infants at high-risk for ASD and diagnosed at 24 months, white matter connectivity abnormalities were present specifically over Broca’s area in the frontal lobes, and more generally in the temporal, parietal, occipital lobes as compared to both low-and high-risk infants not classified as ASD (Lewis et al., 2014).”
There’s more for anyone interested in the actual review and its citations.