A new study from the University of Chicago has investigated whether neural complexity is increased after low doses of LSD, and moderate to high doses of oral THC or methamphetamine.
As highlighted by the researchers, neural complexity correlates with one’s level of consciousness. For example, neural complexity is reduced during a coma or under anaesthesia, and increased during altered states, such as when taking LSD.
This study, published in Neuropsychopharmacology, aimed to better understand whether low doses of LSD between 13 and 26 µg could increase neural complexity without inducing altered states of consciousness, comparing how LSD, THC, and methamphetamine affected consciousness and mood.
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In three separate studies, a group of healthy volunteers received either a placebo or one of the drugs in a controlled setting, where electroencephalography (EEG) was used to record neural activity at the peak of the drug’s effects.
The team found that low doses of LSD seemed to increase neural complexity in a dose-dependent manner. Notably, LSD was found to reduce delta and theta power which was associated with feelings of elation.
Conversely, THC and methamphetamine did not have this effect. In fact, THC was found to reduce alpha power, which was found to be assocaited with altered states, where as metamphetmine increased alpha power in the frontal regions of the brain.
These findings suggest that increased neural complexity is not necessarily connected to altered states of consciousness, and that the role of specific brainwaves in altered states varies between drugs.
The authors write: “These data inform relationships between neural complexity, spectral power, and subjective states, demonstrating that increased neural complexity is not necessary or sufficient for altered states of consciousness.”
The authors encourage further research on the subject in order to explore whether the increased complexity observed with microdoses of LSD has cognitive, behavioural, or therapeutic implications, and to further examine the role of alpha desynchronisation in mediating altered states of consciousness.
