Rats Give Clues on How Stimulants Control ADHD?

Modern treatment methods today for ADHD have always been a focal point of controversy, especially regarding the use stimulants to control the condition. Every time the word ‘stimulant’ comes into play, there will always be a pro-use group and an anti-use group. This will heat up once brand names are mentioned; Ritalin, Concerta and Adderall. But the main thing why stimulants for ADHD are highly controversial is that its precise mechanism is poorly understood even by experts.

A study done by investigators from SUNY Downstate Medical Center on rats reveal some hints that there is an abnormality regarding dopamine receptor D4, a subtype of receptor that is activated by the neurotransmitter dopamine, among individuals with ADHD.

 

What is Dopamine receptor D4

Dopamine receptor, including the subtype D4, is an important component in neurological process like motivation, pleasure, cognition, and memory, learning and motor control. It is also a target by several medications, including stimulants and sedatives.

Abnormalities in dopamine receptor D4 is also linked to conditions mental disorders like schizophrenia, Parkinson’s disease, bipolar disorder, addictive behavior and eating disorders.

 

The study

The experiments in rats reveal that people with ADHD may have some degree of abnormality in dopamine receptor D4. In normal people, the use of stimulants increases activity of dopamine receptor to exert feelings of excitement, jitteriness and alertness. While among individuals with ADHD, using stimulants on a malfunctioning dopamine receptor D4 works otherwise; there is a paradoxical reduction of motor activity and they are able to exert more concentration in tasks.

 

Controversy from the start

The use of stimulants for ADHD started in 1937 when Dr. Charles Bradley administered Benzedrine (racemic mixture of amphetamine) to group of children with hyperactivity and learning disorders. Amphetamines are then used as a stimulant for soldiers fighting during World War II. It showed spectacular results to the children (who regarded Benzedrine as ‘arithmetic pills’), and it ushered a new era in pharmacology and eventual recognition of ADHD, amidst controversy, as a distinct medical condition.

Starting from the 1950’s, millions of children and adults were given stimulants to control hyperactivity, even though the exact mechanism of action is not yet fully understood. Many just can’t accept how stimulants, which normally amplify stimulatory responses, can improve concentration and restrain excess motor activity.

The study is now available in the recent edition of the journal Neuropharmacology.

 

 

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