ADHD has been associated with mixed dominance. Most people are unilaterally dominant. Unilaterally dominant people have an eye, ear, hand, and leg, which are dominant on the same side of the body.
Mixed dominance or mixed brain lateralization refers to a condition where the individual is ambidextrous or where the individual is right handed but left leg, left eye, or left ear dominant or any combination of incongruous hand, leg, eye, or ear dominance. To tell what ear or eye is dominant. Take a small earpiece and put it up to your ear, the ear you choose is your dominant ear. To tell what eye is dominant, take a kaleidoscope and look through it. The eye you chose to look through the scope is your dominant eye. You can kick a wall or ball (put shoes on) to determine which foot is dominant.
Mixed handedness and mixed dominance has been studied and was found to be correlated with atypical cerebral symmetry and with mental health problems such as ADHD. A study published in February of 2010 concluded that mixed handed individuals were more likely to have language, scholastic, and ADHD symptoms.
When my Primarily Inattentive ADHD son had his vision therapy evaluation the optometrist found that he was left eyed and left eared but right footed and right handed. The optometrist reported that this explained the following symptoms:
* A tendency to misplace objects in his personal space
* A tendency to rotate his papers strangely when writing
* A tendency to tip his head 40 degrees when writing
* Difficulty with left and right side of letters (“Mommy is this the way the letter ‘P’ goes??”)
* Difficulty making decisions
* Poor handwriting
* Difficulty with Organization
* Difficulty with gross and fine motor movements
* Learning difficulties
* Difficulties performing task that cross the body midline
Crossing the mid-line work is any left side of the body movement that is performed with your right side or vice versa. As you can guess, tasks such as reading and writing require cross body movements, as your eyes must scan the page from left to right.
Optometrist and Occupational Therapist believe that for the brain to work efficiently the brain must establish dominance. A brain with a cross dominance will have difficulty organizing information and will find that learning information visually and auditorily more difficult.
The brain of a mixed dominant person is not organized in an efficient manner so retrieving information is also more difficult. According to specialist in this area, retrieving information when the cross dominant individual is anxious or upset is more difficult still.
In the late 1990s parents were reporting to physicians that left-handed kids were more likely to have symptoms of ADHD. Studies looking into these reported phenomena did not support this claim. These same studies, however, did find an association between anomalous lateral brain functioning and the symptoms of ADHD.
It does not take much imagination to see that issues with cross dominance will at best worsen the symptoms of ADHD and at worse may somehow be related to the cause of ADHD. As far as I know no studies have been performed that specifically looked at how treating cross dominance problems such as the inability to cross the mid-line affect the symptoms of ADHD.