A brain circuit involved in addiction has been recognized as one of the key pathways after investigators analyzed smokers who immediately lost their nicotine dependency following brain damage. The discovery could guide the use of brain motivation devices to help people quit cigarettes, alcohol and other drugs, says Juho Joutsa at the University of Turku in Finland.
To better recognize the brain areas involved in addiction, Joutsa’s crew looked at the brain scans of 34 individuals who suddenly lost the desire to smoke after a stroke, which involves damage to a small part of the brain, or who exhibited brain damage from a physical injury. It’s an outstanding change in behavior, says Joutsa. They entirely lost the urge to smoke.
The investigators compared these brain scans with those of 69 smokers who continued their smoking practice after a brain injury. Those who lost the desire to smoke had damage to one of three areas: the dorsal cingulate, the lateral prefrontal cortex or the insula or other regions of the brain with strong networks to these three areas. This should be seen as a habit circuit, says Joutsa.
Nevertheless, the quitters didn’t have impairment to the medial prefrontal cortex, which was already known to inhibit activity in the other three brain areas. Situated in the centre of the forehead, the medial prefrontal cortex is thought to be a fourth key area of this circuit. Targeting it via TMS could help people overcome addiction, says Joutsa. Transcranial magnetic stimulation (TMS) is one such device, which uses this method, and is approved to help individuals quit smoking in the US. It comprises going to a clinic where doctors hold a small device over the head that momentarily boosts activity in part of the brain. But it is unclear how it works and it isn’t used widely.
Observing a separate group of 186 people with brain injuries, researchers further found damage in this circuit was also linked to a lower likelihood of alcohol addiction. Other clinicians have previously informed how three individuals with brain damage in this circuit suddenly lost dependencies to either opioids and alcohol, multiple illegal drugs, or alcohol and nicotine. Although TMS is already used to help some people quit smoking, the new discoveries may suggest ways to improve the effect, says Nick Davis at Manchester Metropolitan University in the UK. This is very influential, as it means we can find areas where we might increase or decrease brain activity using techniques like magnetic or electrical motivation.