The way in which low doses of LSD combat anxiety symptoms is similar to that of certain classes of frequently prescribed antidepressants and anti-anxiety drugs, according to the work of a Montreal researcher.

While it is already known that microdoses of lysergic acid diethylamide (LSD) combined with psychotherapy could alleviate anxiety and depressive symptoms in patients with severe psychiatric or neurological problems, the neurobiological mechanisms responsible for this beneficial effect were poorly understood.

"We have been trying to understand what the mechanism of action of LSD is and in what mental illnesses it might be used," said Dr. Gabriella Gobi, the senior scientist in the Brain Repair and Integrative Neuroscience Program at the Research Institute of the McGill University Health Centre.

Gobbi and her colleagues found that LSD triggers mechanisms similar to those of selective serotonin reuptake inhibitors such as Prozac, Zoloft, Celexa, Cipralex, etc.

Previous studies have shown that prolonged stress reduces the activity of neurons that transmit serotonin. Researchers have now found that LSD promotes the nerve transmission of serotonin, a neurotransmitter that plays a crucial role in feelings of well-being, much like the better known SSRIs.

Experiments with mice have also shown researchers that LSD can help rebuild the branches of neurons that transmit the electrical signal to the nerve cell body, which are often damaged by stress.

"We saw that animals taking LSD did not have symptoms of anxiety, so LSD could prevent stress-induced anxiety through a mechanism on the serotonin system," said Gobbi, who has studied psychedelics for many years.

Further studies will now be needed to see if LSD could have the same utility in humans.

And while psychedelics have been used recreationally for a very long time, they are not to be taken lightly, Gobbi warned.

"You have to be careful," she said. "We know that low doses, for short periods, can be used, for example, in resistant depression, in anxiety, in post-traumatic stress.

"It is absolutely necessary to have the help of a therapist, a psychotherapist or a doctor. These are dissociative substances that ... should always be administered under the direction of a physician or therapist."

Moreover, only a small group of patients with anxiety and stress problems could benefit from taking psychedelics, she added. Clinical studies are ongoing to get a clearer picture, and researchers are waiting for results before they can be considered for more patients, said Gobbi.

The next step for Gobbi's team will be to evaluate the mechanisms of action of other psychedelic substances, such as psilocybin (the active component of magic mushrooms) and ketamine.

The findings of this study were published in the journal Neuropsychopharmacology. The work was conducted in collaboration with researchers in psychiatry at McGill University, as well as researchers in neuroscience at Vita Salute San Raffaele University and in pharmaceutical and pharmacological sciences at the University of Padua, in Italy.

-- This report by The Canadian Press was first published in French on March 17, 2022.