A single dose of the psychedelic drug LSD appears to alter the brain activity of dogs with autism-like traits during social interactions. Unlike other canines, these pooches were unable to synchronize their neural activity with humans when being petted, yet all that changed when they ingested the trippy substance.

Describing their findings in a new study, the researchers explain that social interactions between humans are driven by “interbrain activity coupling,” whereby the individuals involved develop matching patterns of neural activity in certain key brain regions. Wondering whether this mechanism might exist between species, the study authors used electroencephalography to record the brain activity of humans and dogs as they mingled.

Results showed that such synchronization does indeed occur between the two species during both mutual gazing and petting. Specifically, the researchers found that interbrain activity coupling was localized within the so-called frontoparietal network, which is involved in the attentional selection of sensory information.

Within this network, the frontal region typically processes visual cues while the parietal region takes care of somatosensory information. Accordingly, the data showed that synchronization was strongest in the frontal region when dogs and humans gazed at each other, while petting triggered stronger coupling in the parietal region.

The strength of this synchronization was also seen to increase across the five days of experiments, as dogs became increasingly familiar with their handlers. Further analysis of the information flow during brain activity coupling revealed that humans are very much the leaders and instigators of this synchronization, with dogs following the social cues of their two-legged companions. 

Summing up these observations, the study authors explain that “the strength, direction, and attention-associated brain regions of the interbrain activity coupling during human-dog interactions are similar to those during human-human interactions.”

However, when the experiments were repeated using dogs that had been bred as a model of autism spectrum disorder (ASD), no such synchronization was seen between the animals and their human co-participants. These dogs also displayed reduced attention during interactions with people.

Citing previous studies that have highlighted the ability of LSD to enhance social behavior in mice, the study authors decided to investigate whether the drug could alter the brain activity of these dogs. Sure enough, they found that “a single dose of LSD rescued impaired interbrain coupling and joint attention in… mutant dogs, suggesting that LSD may potentially ameliorate social deficits in [ASD].”

“There are two implications of the present study,” said study author Yong Q. Zhang in a statement. “One is that the disrupted inter-brain synchronization might be used as a biomarker for autism, and the other is LSD or its derivatives might ameliorate the social symptoms of autism.”

However, the researchers point out that the mechanism by which LSD brings about these effects “remains unclear”, and further work is required in order to determine whether or not the drug could be used clinically.

The study has been published in the journal Advanced Science.