Methylphenidate (MPH) and Dex-amphetamine (D-AMP) are the two molecules most commonly used as treatment for ADHD. They are both psychostimulants.

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Stimulants work by increasing dopamine neurotransmission. MPH is a dopamine re-uptake inhibitor and D-AMP is both a dopamine re-uptake inhibitor and a dopamine stimulant. They don't give you dopamine, they slow down the rate at which your dopamine is broken down. They inhibit the pac-man that chews up your dopamine, so more dopamine molecules hit the downstream receptor and whiz, your circuits speed up.

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At therapeutic doses, they have and up and a down phase. The stimulant kicks in, you get better cognitive function. Then it wears off and you go back to your usual self.

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Some people worry that stimulants are addictive. Not so. If you take them as prescribed you don't get high, you just get, from down, up to normal.

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So by extension, stimulants are not cheating. You are using a medicine, prescribed for you to go from under-function to normal function.

 

In Canada, Dex- amphetamine is available in four different formats, in order from fastest to slowest acting: Dexedrine IR®, Dexedrine SR®, Adderall XR® and Vyvanse®.

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Methylphenidate is available in four different formats as well, in order from fastest to slowest acting: Ritalin IR®, Ritalin SR®, Biphentin® and Concerta®.

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Psychostimulant medications have been reported to reduce the problematic hyperactive symptoms in approximately 60-70% of children with ADHD. Research and clinical findings indicate that the ability to sustain attention increases; that social behaviours improve, and that hyperactivity and impulsivity decrease with the use of psychostimulants [10]]. 

 

Swanson and fifteen co-authors conducted a comprehensive examination of 341 reviews of the effects of stimulant medication on children with attention deficit disorders. Their review found that stimulant medication was ineffective for 25 to 40 percent of children with ADHD. A large proportion of those responding to stimulants also showed im- provements on a placebo (a harmless sugar pill).

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Swanson found that amongst those that responded to stimulant medication, temporary management of over activity, inattention and impulsivity could be expected, as well as temporary improvement in compliance. Hyperactivity and aggression may be reduced, and consequently the amount of academic work completed may increase in the short term (months). However contrary to the hopes of parents and practitioners, there was no evidence of long term sig- nificant improvement in reading, athletic or game skills, proactive social skills, learning and achievement other then improved attending.

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Stimulant medication allows many children with ADHD to spend a near-normal day at school, and gives teachers and parents a welcome relief from their disruptive or inattentive behaviours. However medication does not treat the causes of ADHD, only some of its symptoms.

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Stimulant Medications only work when in the system, and since they clear the system in about 4 hours, up to three doses may be required each day. When medication is stopped, even if after extended periods, many of the undesir- able behaviours reappear. Clinical experience indicates that a common complaint of parents whose children take medication for ADHD is that while the child is less hyperactive and is more on task at school, the same child has difficulties getting started in doing homework at home, continues to experience difficulties following rules, and cannot understand why certain behaviours are inappropriate.

 

A review of the literature reported by Barkley revealed that between 79% to 90% of children on these medications experienced undesirable side effects. Side effects reported in clinical studies are: loss of appetite, headaches, sleep problems, gastrointestinal disturbances, increased tic disorders, mood instability and growth reduction. A small but significant number of children show negative physiological side effects that do not diminish or resolve over time despite cessation of the medication.

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Psychostimulants are not appropriate for all children with ADHD. According to the manufacturer of Ritalin, it is not recommended for children with anxiety or motor tics or Tourette's Syndrome due to the risk of exacerbating these conditions.

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Barkley, R.A., Diagnosis and assessment of attention deficit-hyperactivity disorder. Comprehensive Mental Health Care, 1991. 1(1): p. 27-43. 10. Barkley, R., Attention deficit hyperactivity disorder: A handbook for diagnosis and treatment. 1990, New York: Guilford Press. 11. Swanson, J.M., et al., Effect of stimulant medication on children with Attention Deficit Disorder: a "review of reviews". Exceptional Children, 1993. 60(2): p. 154-162. 12. Lubar, J.F., Discourse on the development of EEG diagnostics and biofeedback for attention-deficit/hyperactivity disorders. Biofeedback and Self Regulation, 1991. 16(3): p. 201-225.

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Non-stimulants

Strattera® is a noradrenaline re-uptake inhibitor (NRI). It turns on noradrenaline and some dopamine circuits in the part of the brain that regulates focus and attention. It can be as effective as a stimulant, but it does not work as quickly or consistently. 

It is most helpful in situations where stimulants cannot be used; such as in a patient who has tics or seizures or has recently been abusing stimulants. Common Strattera side effects include fatigue and upset stomach. These can be minimized by starting the medication at low doses, taking it in the evening rather than the morning, and taking it with food. 

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Modafinil  - There is not enough data supporting the use of this medication in adults with ADHD.

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Intuniv ® Guanfacine SR, is an A2 Agonist which has sedating properties. The short-acting version is used to lower blood pressure and as a treatment for heroin withdrawal.  Intuniv is used in ADHD, usually as an add-on to a stimulant, in people with anxiety.