Richard G. Petty, MD

More on Brain Laterality and Attention Deficit Disorder

I recently wrote about the connections between attention deficit disorder and disturbances of the normal lateralization of the brain.

I had a very interesting question from a correspondent:
"Is there any CHANGE in handedness related to the use of stimulant medication?

I have been taking dexadrine (RP: That’s methamphetamine) at 60 mg/day for several months now to address ADD after diagnosis as an adult. I have found that I now use my left hand for some tasks that I would have solely used my right hand previously. For example, I am painting trim with a brush at home currently and have found myself, without forethought, switching hands and cutting in against the walls and other paint colours with my left hand at a skill level that matches my right hand. Is it possible that this is the result of increased "cross-talk" between the hemispheres? My father was not classically ambidextrous but he did play hockey and golf as a "lefty" while writing using his right hand.”

This is a fascinating question. There is evidence of shifts of functional lateralization in a number of situations, including severe changes in mood.

There is also some experimental data to support what the writer’s observations, though most of it comes from research in children.

  1. A study from the Netherlands showed that in children treated with methylphenidate, their manual dexterity and handwriting improved and became more accurate.
  2. Research from Germany using high density magnetoencephalography (MEG), showed that treatment improved activity in the frontal lobes of the brain.
  3. Investigators in New Mexico found that unmedicated children with ADHD had slower reaction time in their legs, which got better, particularly in the right leg, when they were given treatment.
  4. Another study, this time from Israel, also showed that children with ADHD had a lateralized attentional deficit that got better when they were treated.
  5. Children off treatment seem to have lower activity in the right hemisphere of the brain, which normalizes with treatment.
  6. Stimulant medications do not themselves seem to have an impact on inter-hemispheric transfer. But what it may do is to improve the imbalance between the hemispheres.

So I would suspect that the writer’s brain is becoming generally more efficient.

And his letter has also suggested a small research project.

I sense a grant proposal in our near future.

About Richard G. Petty, MD
Dr. Richard G. Petty, MD is a world-renowned authority on the brain, and his revolutionary work on human energy systems has been acclaimed around the globe. He is also an accredited specialist in internal and metabolic medicine, endocrinology, psychiatry, acupuncture and homeopathy. He has been an innovator and leader of the human potential movement for over thirty years and is also an active researcher, teacher, writer, professional speaker and broadcaster. He is the author of five books, including the groundbreaking and best selling CD series Healing, Meaning and Purpose. He has taught in over 45 countries and 48 states in the last ten years, but spends as much time as possible on his horse farm in Georgia.

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