A few weeks ago, Mo over at Millgrams Blog asked me to do a post on ADHD. In his comment to the post, he raised several interesting issues. So many issues, in fact, that responding to them requires a series of posts. In this post I'm going to cover the general facts about ADD meds and how they work. In following posts I'll talk about the legal issues surrounding ADHD meds. The final post will deal with the social issues that come with medicating ADD.
Since this post is pretty long, I've put the topic sentences in bold.
ADHD meds generally fall into one of two categories: amphetamines and methylphenidates. Both of these meds are psychostimulants, but they actually stimulate activity throughout the central and peripheral nervous system. This means that they increase production of several neurochemicals, including dopamine. Dopamine plays a critical role in allowing the brain to focus and follow through on tasks. One theory regarding ADD is that it's basically a "dopamine shortage" -- medication increases dopamine, which increases focus.
Dopamine is also the brain's reward chemical. When you're enjoying a pleasurable activity like sex or a good meal, your brain releases dopamine to "reward" you. Dopamine feels good. If sex and food bring about good feelings, you're more likely to survive and pass on your genes. Humans being what they are, we also get a dopamine hit from things like finishing a task, achieving a goal, and even learning.
Since dopamine feels so good, humans have developed plenty of recreational drugs that stimulate its production. Every drug, from caffeine to cannabis to cocaine, releases dopamine. The same is true of psychostimulants. Taking stimulants in high enough amounts produces a "high" in most people -- and this is why people abuse them. They're also highly addictive, and tolerance can be built up quickly. Addicts meed more and more of the drug in order to get that initial high. Needless to say, this leads to addiction and all kinds of negative consequences.
So why doesn't ADHD medication quickly lead to addiction?
The first reason is dosage. Though it's less dramatic than lamictal titration, ADD meds are also prescribed at small dosages at first, and then adjusted up until the ADDer feels that her symptoms are being controlled. Generally, pdocs like to prescribe the smallest dosage that will alleviate the ADHD symptoms. This helps to prevent the drug tolerance that can lead to addiction. Many folks with ADHD take their meds for years without ever experiencing any tolerance whatsoever. If tolerance does become a problem, the doctor may suggest a medication break, or switch to another med for awhile.
In most people, stimulants often produce feelings of anxiety and nervousness. For most people with ADD, they produce a feeling of calm. There may be a chemical reason for this, or it may simply be that our brains are suddenly not being bombarded by several things screaming for our attention. We can focus on one thing (OK, maybe a few things) without being pulled away by another urgent matter, and then another, only to find by the end of the day that nothing has been accomplished.
But do people with ADHD *really* have different brains? Neuroimaging of the brains of ADD patients has shown that certain parts of our brains are actually smaller than in "normal" people. This is notable in the frontal cortex area of the brain. What does the frontal cortex do? Glad you asked. The frontal cortex is responsible for executive functions -- planning, working memory, attention, problem solving, verbal reasoning, inhibition, mental flexibility, multi-tasking, initiation and monitoring of actions (list copied from wikipedia.)