An increasing number of children suffer from the consequences of maternal drug exposure during pregnancy. Cannabis is one of the most frequently used substances. This motivated the study, published in “the EMBO Journal", to decipher the molecular basis of how the major psychoactive component from cannabis, 9-tetrahydrocannabinol (or THC) affects brain development of the unborn foetus.
The study highlights that consuming cannabis during pregnancy clearly results in defective development of nerve cells of the cerebral cortex, the part of the brain that orchestrates higher cognitive functions and subserves memory formation. In particular, THC negatively impacts if and how the structural platform and conduit for communication between nerve cells, the synapses and axons, will develop and function. Stathmin-2 is identified as a key protein target for THC action, and its loss is characterized as a reason for erroneous nerve growth. It is stressed that cannabis exposure in experimental models precisely coincided with the foetal period when nerve cells form connections amongst each other.
According to study director Tibor Harkany, who shares his time as Professor of Molecular Neurosciences at the Centre for Brain Research at the MedUni Vienna and the Karolinska Institutet in Stockholm, these developmental deficits may evoke life-long modifications, altering brain functions in those affected. Even though not all children who had been exposed to cannabis will suffer immediate and obvious deficits, the brain changes shown by the Viennese researchers warn that relatively subtle damage can significantly increase the risk of delayed neuropsychiatric diseases. Says Harkany: "Even if THC only would cause small changes, its effect may well be sufficient to sensitize the brain to later stressors to provoke neuropsychiatric illnesses in those affected later in life."
Exactly for these negative effects, a clear distinction should be made between recreational and medical use of cannabis the researchers emphasize: "The medical use of cannabis makes sense since the aim is to treatment illnesses. But upon the recreational use of cannabis during a pregnancy the opposite applies. Consumption of cannabis whilst the foetal brain develops interferes with a physiologically intact and very sensitive system with potentially far-reaching adverse effects for the babies and children concerned".
Service: The Embo Journal
„Miswiring the brain: Δ9-tetrahydrocannabinol disrupts cortical development by inducing an SCG10/stathmin-2 degradation pathway.“ Giuseppe Tortoriello, Claudia V. Morris, Alan Alpar, Janos Fuzik, Sally L. Shirran, Daniela Calvigioni, Erik Keimpema, Catherine H. Botting, Kirstin Reinecke, Thomas Herdegen, Michael Courtney, Yasmin L. Hurd and Tibor Harkany. EMBJ-2013-86035, Jan. 27.