functional resting connectivity. Today features a selection of slides from part of a much larger presentation dealing with co-occurring mood and substance use disorders. The slides pretty much do all the talking, so I'll keep my commentary brief.
Basically, combine stress with genetic vulnerability and bad things happen. Drug abuse involves much the same process. And, of course, the two interrelate. Lifetime drug abuse amongst bipolars is in the 60 percent range.
An under-active prefrontal cortex combined with an over-active amygdala is a recipe for disaster. There is no end to variations on this theme. This one involves a certain genetic variation (allele). Another variation involves kids, whose brains have yet to mature. As opposed to the heart, Dr Volkow pointed out, the brain takes 20 years to develop. Plenty of time for risk-taking activities, such as drug use. Meanwhile, early childhood social neglect impairs brain development. Too much amygdala action, not enough from the PFC and other areas.
Significantly, a good many of the shared candidate genes for bipolar, schizophrenia, and substance abuse have to do with neuroplasticity. Neuroplasticity has a lot to do with how we react to our environment. If our neurons don't hold up well (such as to stress) and maintain cellular function, well, bad things only get worse. Neuroplasticity also plays a role in programmed brain development, all those gear changes that are supposed to represent smooth transitions into adulthood and beyond. Needless to say, for a good many of us, life is not a smooth transit.
This is your brain on drugs.
The brain may be highly differentiated, but with everything literally connected to everything in one way or another, mental illness tends to involve a system failure throughout the brain.