We have known for a long time that dopamine is vital to the “reward” function in our brains. But, dopamine seems to have a much wider-ranging impact, than just this. After all, my grandfather, Sol Kuchlik, of blessed memory, was among the first treated with L-dopa (a form of dopamine) to counteract his Parkinson’s Disease symptoms. So, let’s see where we stand today (this is by no means an exhaustive review….).
Dr Tali Sharot, of University College of London, found that addicts overestimated the pleasure they would gain from taking heroin or gambling, because their dopamine system was dysfunctional. Dr. Sharot’s research group found, using imaging techniques, a signal in the brain linked to how much someone enjoyed a given experience. This signal let the group predict the choices that person made. It turns out that signal is dopamine.
It has also been found that ADHD patients had lower levels of dopamine receptors and transporters (both of these are proteins) in the (brain’s) nucleus accumbens and midbrain. Both of these are part of the limbic system, which is responsible for the emotions, as well as for motivation and reward. The more pronounced the ADHD symptomology, the lower the two protein levels. This is probably why stimulant medications (Ritalin, which is related to caffeine, is one such drug) treat ADHD symptoms- by raising the dopamine levels in the brain. I already discussed that raising dopamine levels affords Parkinson’s patients the ability to reach functional levels- no slurring of speech, better fine motor control, etc.
The findings also provide more reasoning as to why people with ADHD seem to be more prone to drug abuse and obesity. It turns out that they may be compensating for the deficient reward system that exists in their brain.
It also means that ADHD children may not be deliberately disrupting their classroom; it may just be a deficiency of the dopamine levels or receptors. (It also means that educators MUST augment the interesting/exciting levels in their classrooms to engage these kids and help them learn. I probably was one among them…)
[There was a study years ago showing that Parkinson’s Disease skips a generation. Maybe, this is why I was/am hyperactive- when I was growing up, attention deficit disorder and hyperactivity were separate syndromes. If Parkinson’s skips generations, AND if- since it can be treated with dopamine- this is related to lowered dopamine or dopamine receptor proteins, then it would make sense that hyperactivity or ADD could manifest itself in one such an individual.
It seems that dopamine also explains why some people are more creative than others. Dopamine receptor genes are linked to the ability to achieve divergent thought. We know (knew) that families with members demonstrating schizophrenia or bipolar disorders often have other members who were highly creative. The ability to make unusual or perhaps bizarre associations is found in both creative individuals and schizophrenics. Dr. Fredrik Ullen of the Karolinska Institutet used this knowledge in a study to demonstrate that the dopamine system in otherwise healthy, but highly creative people matched those of people with schizophrenia. Dr. Ullen found that creative people had lower densities of D2 receptors (there are five dopamine receptors of which were are aware; two are similar to D1, three are similar to D2). Schizophrenia, drug abusers, and now creative people all are affected by D2 receptors. The D2 receptors for creative types and schizophrenics are primarily found in the thalamus, the relay center that filters information prior to its arrival in the cortex (responsible for cognition and reasoning). The lower density of receptors means there is lower signal filters- and a higher flow of information- to the cortex. So, this means that thinking out of the box may really be the fact that the box is much bigger for creative types (little or less filtering of information to the cortex).
So, that’s the science, as we know it. But, here’s more food for thought. While my (ex)wife and I were “working on improving our relationship” (not, as the facts demonstrated), I was offered neurontin, a drug used to treat epilepsy, and in off-label uses for ADHD and schizophrenics. I also was offered the SAME drug by my physician during this same time period, as a means of correcting sleep apnea. While I was taking the drug, I noticed that my brain seemed to work slower- not really (since I did not get tested for this fact)- but I could discern a miniscule time lapse, during which I knew what I was going to say and do- before I did or said it. I now believe this drug may have been affecting my D2 receptors or changing my dopamine levels; maybe not enough to make a large difference, but enough for me to recognize the filtering mechanisms of the thalamus were altered.
I mention this because neurontin is NOT approved for these uses- but maybe it should be, because it does work for drug withdrawal, bipolar disorders (with much fewer side effects), and opiate withdrawal. With these new testing processes and results, it is time to reexamine many of our “hard and fast rules”…
