The evidence is nicely surveyed in this book:
Handley, J.B.; Handley, J.B.. How to End the Autism Epidemic. Chelsea Green Publishing. Kindle Edition.
in particular a recent paper cited there
(Christopher Exley et al., “Aluminium in Brain Tissue and Autism,” Journal of Trace Elements in Medicine and Biology 46 (2018): 76–82.)
found that not only were the five brains of autism suffers who died that were autopsied all very high in aluminum, but the aluminum was found within cells supporting the theory that it was transferred there by macrophages which pick up the nanoparticles and microparticles of vaccine aluminum.
Also there are a number of papers confirming various steps of the theory that vaccine aluminum is transported to the brain and causes inflammation via raising Cytokine Interleukin – 6 levels there.
Another survey of the causal model. Note published before Exley's measurement of the high level of aluminum in autists.