People with attention-deficit/hyperactivity disorder (ADHD) are significantly more inattentive, hyperactive, and/or impulsive, that those without the illness. It can lead to not only more poor performance at school or work, but also can greatly decrease the quality of social relationships. Children with untreated ADHD tend to be social outcasts.

Importantly, the incidence of ADHD has skyrocketed in recent years. Without a doubt, there’s a complex interplay of factors that has lead to this. I would venture to say that this graph below means that there are a large number of environmental factors that cause symptoms of ADHD these days. As such, many can be treated without resorting to medication.

As with 0ther mental illnesses, the likelihood of having ADHD grows a lot if a family member has it.

ADHD involves a lack of dopaminergic (D1) and adrenergic (α2A) activity in the prefrontal cortex, the most executive, cognitive region of the brain. Dopaminergic activity reduces background noise (distraction), and adrenergic activity increases communications between neurons (focus). Not surprisingly, it was found that children and adolescents with ADHD, and who had a defect in the gene controlling the expression of α2A, responded particularly well to Ritalin (methylphenidate). One’s genetic code for dopamine is also important, likely more so. The brain itself was found to be about 3% to 4% smaller in people diagnosed with ADHD.

The current Diagnostic Statistical Manual lists ADHD as made up of two general parts, one of which must be present for a diagnosis…

  • Inattention
    • Selective attention
      • Trouble sustaining effort to follow through and complete tasks
      • Issues in the dorsal anterior cingulate cortex (dorsal ACC)
    • Sustained attention
      • Being easily distracted and not paying attention to detail
      • Issues in the dorsolateral prefrontal cortex (DLPFC)
  • Hyperactivity and impulsivity
    • Hyperactivity
      • Moving a lot, difficulty being still
      • Issues in the prefrontal motor cortex
    • Impulsivity
      • A significant lack of reasonable patience
      • Issues in the orbitofrontal cortex (OFC)

For further reading, please see the more complete criteria and explanation of ADHD.

It’s estimated that 3%-9% of children across the world have ADHD that greatly decreases their quality of life. Thus, the worldwide diagnosis rate of  ADHD, just over 5%, fits in well. By contrast, the percentage of children aged four to 17 diagnosed with ADHD in the United States, is about 11%.

Three boys for every girl, have the symptoms of ADHD. Perhaps this is partly due to the more outgoing nature of boys, which society has a hand in creating. Also, the great majority of research into ADHD has included boys.

Usually by age four, parents are able to detect something wrong, if their child has ADHD. Things become much more obvious by age six. These issues grow as their child makes their way through school. Impulsivity usually starts declining by school-age. From an outsider’s perspective, impulsivity may not seem to persist at all but it can, such as with unprotected sex, or reckless driving. Hyperactivity decreases more than impulsivity by adulthood, but inattention stays constant, and the presence of another mental illness becomes much more likely.

By one estimate, from 30%-70% of people with ADHD as kids experience the same difficulties as an adult. Another, more exact guess, is around 50%. Those who don’t have significant symptoms as adults literally grow out of it: they’re able to catch up by rapidly creating more synaptic connections in the prefrontal cortex.

About half as many adults as children are diagnosed with ADHD. That said, it’s much more difficult to spot in adults. So much so that about 20% of adults with ADHD are diagnosed; this rate for children and adolescents is 50%. It can be very difficult to recall one’s behavior when they were under seven years old, which is when symptoms had to begin by in order to diagnose it. Another reason is that by adulthood, most people without properly treated ADHD, have a comorbid (two diseases present) illness. One rule of thumb is to treat these illnesses in descending order: drug abuse, mood instability, anxiety disorders, ADHD, and finally, tobacco use.

In comparison to people without ADHD, left untreated, ADHD can greatly decrease quality of life. This includes not being paid as much for employment, fewer years of attending college, a higher divorce rate, and more drug abuse.

Growing up with parents who smoked, eating a lot foods with preservatives, and premature birth, are a few environmental risk factors.

Sources: Abnormal Psychology: An Integrative Approach, Condensed Psychopharmacology 2013: A Pocket Reference for Psychiatry and Psychotropic Medications, Stahl’s Essential Psychopharmacology