"In this review, we summarize the information from multiple studies showing that an abnormal gut microbiota is related to ASD. First, we reviewed the relationship between the gut microbiota and the CNS. Second, we defined the role of the gut microbiota in ASD. Finally, we described some potential therapies for modulating the gut microbiota in patients with ASD. Many recent clinical studies have shown that treatments that regulate the gut microbiota result in improvements in ASD symptoms (Critchfield et al., 2011; Tomova et al., 2015)."
NOTE: This is a very good paper, inasmuch it details WHICH probiotics are beneficial - and further discusses how diet affects the microbiome.
Source: Frontiers in Neuroscience