The best medicine for ADHD Inattentive (ADHD-PI) or Inattentive ADD is probably not Ritalin. There are some psychiatrists that believe that Inattentive ADD or ADHD-PI may not be ADHD at all and that patients with this subtype of ADHD may respond totally differently than the other subtypes to stimulant medication.
Dr. Russell Barkley, a foremost authority on ADHD, has written this about treating the inattentive subtype of ADHD: “These children do not respond to stimulants anywhere near as well as AD/HD hyperactive, impulsive children do. Only about one in five of these children will show a sufficiently therapeutic response to maintain them on medication after an initial period of titration. Oh, you’ll find that about two-thirds of them show mild improvement, but those improvements are not enough to justify calling them clinical responders, therapeutic responders. Ninety-two percent of AD/HD children respond to stimulants. Twenty percent of these children respond to stimulants. And the dosing is different. AD/HD children tend to be better on moderate to high doses. Inattentive children, if they’re going to respond at all, it’s at very light doses, small doses. “
Many people with ADHD-PI however, successfully use stimulant treatment. For some people even a mild improvement is reason enough to stay on the medication. The best medicine is always tailored to each individual but there is data that Ritalin works less well for ADHD-PI than the Adderall family of drugs. It would be nice, I think, to have an easy and quick reference for the medicines used to treat for Primarily Inattentive ADHD. To better understand the treatments available, a very basic lesson in the biology of ADHD is handy.
All types of ADHD are thought to be the result of a problem with neurotransmitters in our brain. The two neurotransmitters that cause the major symptoms of ADHD are Dopamine and Epinephrine (norepinephrine). Very simply stated, a low amount of dopamine in our brain will cause hyperactivity and impulsivity. A low amount of epinephrine will cause lack of focus, lethargy, and mental fatigue. Serotonin, another neurotransmitter, is secreted and depleted in tandem with dopamine and epinephrine. Low levels of serotonin make us irritable, tired, and depressed. The level of circulating serotonin is related to the levels of these other two neurotransmitters and vice versa.
All the treatments for ADHD work to optimize neurotransmitter function in the brain. The Ritalin (Methylphenidate) family works by increasing both brain dopamine and epinephrine. The Adderall (Amphetamine) family works by increasing brain epinephrine and dopamine but this family of drugs increases dopamine by only about half as much as Methylphenidate. Strattera (atomoxetine) works by increasing brain norepinephrine. Guanfacine (Intuniv) regulates the flow and effectiveness of neurotransmitter receptors in the brain in a way that reduces hyperactivity, improves working memory, and diminishes impulsivity, and distractibility.
So what is the best medicine for ADHD-PI? Some doctors believe that the Adderall family works better than the Ritalin family for the inattentives as the medication’s effects on norepinephrine are greater than the effects on dopamine. All stimulants can make some inattentives anxious but ADHD-PI patients seem to tolerate the amphetamines better than they tolerate the Ritalin family.
It would seem that using this very simple understanding of the biology of ADHD, that Strattera should work the best for ADHD-PI. The reality is that Strattera only works for some patients with ADHD-PI. We are not sure why this is the case. It would also seem that Intuniv would work poorly for folks with ADHD-PI as its main effect is on hyperactivity. The reality is that some doctors have found that Intuniv works well for ADHD-PI patients.
Because some folks with ADHD also have problems with depression and anxiety, antidepressants such as the tricyclics (Elavil, Norpramin, Tofranil) which work on Norepinephrine and Serotonin are sometimes prescribed. There are many patients who report relief of their inattentive symptoms when they are treated with the tricyclics. The SSRIs, the selective serotonin reuptake inhibitors, (Prozac, Paxil, Celexa) work only on serotonin and are sometimes used in conjunction with the stimulants to treat ADHD-PI with depression but may also help inattention.
All of these medications can have side effects. The stimulants can cause weight loss, anxiety, and sleep issues. Intuniv can cause drops in blood pressure and sleepiness, Strattera can cause sexual dysfunction and has as do the SSRIs a warning for pediatric patients regarding an increased risk of agitation, irritability and suicidal thinking. Usually the medication side effects are mild or rare but when they are not, they will unfortunately dictate what treatment can be used.
Some researchers believe that once we have mapped the genetic issues involved in ADHD, we will be able to tailor individual treatments for everyone with ADHD. This is a tall order as the neurotransmitter actions in the brain are complex and none of the neurotransmitters work independently. The variety of symptoms in ADHD are also interrelated and complex.
Given the individual and unique symptom manifestation of ADHD, and the differences in the occurrence and tolerance of medication side effects, the treatment of ADHD-PI will always be, to some extent, a process of individual trial and error.