Dopamine and anxiety

Anxiety disorders are probably the most common co-existing disorder for those with inattentive ADHD. What's more dopamine, a neurotransmitter that's extensively involved in ADHD, may also be implicated in anxiety disorders.

According to researchers, some people with anxiety disorders may be suffering from a shortage of dopamine in the amygdala, a part of the brain involved in regulating our "fight or flight" responses to stressful situations

Interestingly when I tried dexamphetamine for ADHD it didn't have much of an effect on my inattention, but it did have a positive effect on my mood and anxiety symptoms. However, I decided to discontinue using the drug as it caused unpleasant rebound symptoms when it wore off.

At present the most frequently prescribed medications for generalised anxiety are the SSRIs (selection serotonin reuptake inhibitors, which include Prozac) which are designed to raise the level of the neurotransmitter serotonin in the brain. However, not everyone responds to SSRIs (in my case they don't seem to have any mental effects at all). Perhaps this research will lead to the development of sustained release drugs will can mildly raise dopamine levels in the amygdala without causing over-arousal or withdrawal symptoms.

Gender and ADHD

This post will probably raise a few hackles but I came across this article about "ADHD myths" which propagates a few myths of its own.

One of these is the claim that ADHD is just as common among girls and boys.
Now ADHD may be under-diagnosed in girls but doesn't mean the percentage of boys and girls with ADHD are similar for each subtype of ADHD.

In the case of "classic" hyperactive/impulsive ADHD there are definitely more boys than girls with the disorder. You just don't see as many girls with extreme impulsivity or hyperactivity, and with good reason - the parts of the frontal lobes of the brain which control behaviour are usually more developed in girls and boys.

In the case ADHD combined type the gender gap is narrower. While there are probably still more boys than girls have this form of the disorder, it is under-diagnosed in girls and often more difficult to spot. For example, while a boy with ADHD combined type may be physically hyperactive (the most obvious indication of ADHD) a girl may be a "chatty cathy" who talks excessively and is overly dramatic.

In the case of inattentive ADHD, the number of girls and boys with this subtype are about the same. Again, this makes sense from a developmental point of view - inattentive ADHD is not a behavioural disorder like hyperactive/impuslive ADHD, so it doesn't make scientific sense for there to be a big gender difference.

Here's a good article describing how the different subtypes of ADHD tend to appear among girls.