Left Temporal Lobe Functions & ADHD

Attention Deficit Hyperactivity Disorder (ADHD) is the presence of at least six Inattentiveness and/or six hyperactivity-impulsivity symptoms persistent over the course of at least six months, causing some impairment by the age of 7, presenting in two or more settings, and not occurring during an acute or chronic psychotic episode. According to the National Institute of Mental Health (NIMH), children with this disorder may "act quickly without thinking first; are unable to sit still; walk, run or climb when others are seated; talk when others are talking; daydream excessively; and are easily sidetracked by what is around him or her." While there is little research specifically linking specific functions of the temporal lobe to this disorder, functions of the left temporal lobe can be compared with known neurological components of ADHD.

The Temporal Lobes

• The temporal lobes are the portion of the cerebral cortex situated inside the ears and extending toward the back of the brain on both the left and right hemispheres of the brain. Their primary functions are auditory and speech processing, language and visual recognition and long-term memory.

Damage to the Temporal Lobe

• According to the Center for Neuroskills (CNS), Kolb and Wishaw (1990) showed that temporal lobe damage can cause disturbances of auditory sensation and perception; selective attention of auditory and visual sensory input; impaired language comprehension; impaired organization and categorization of verbal material and long-term memory; altered sexual personality and sexual behavior; and disorders of visual perception.

Left Temporal Lobe Damage

• CNS also states, citing studies by Milner (1968) and Read (1981), that left temporal lesions may result in "decreased recall of verbal and visual content, including speech perception ... disturbed recognition of words ... [and] impaired memory for verbal material."

Neuropathology of ADHD

• In 2004, Psychiatric News reported a study by Sowell and Peterson comparing 3-D MRI scans of children with diagnosed ADHD against a control group. The study showed children with ADHD exhibiting increased gray matter in the posterior temporal cortex, a part of the temporal lobe associated with attention and impulse control, as well as a significant reduction in brain size in both anterior temporal areas.
  In addition, a 2007 study by NIMH researchers showed that the wiring of the prefrontal and temporal cortices of the brain was delayed by as much as five years in some places. However, the study also noted that the motor cortex in children with ADHD evolved faster than normal, which, they pointed out, "might account for the restlessness and fidgety symptoms common among those with the disorder."

Left Temporal Lobe Functions and ADHD

• While the two sides of the brain always work in tandem with each other, we know that the left side of the brain is typically responsible for linguistic, rational and logical thinking, as well as organization. Since imaging studies show ADHD to have a bilateral physiopathology, one could only conclude that the effects of left temporal cortical overdevelopment or underdevelopment would be consistent with the findings of Kolb and Wishaw, Milner and Read, though since imaging research on ADHD is still in its infancy, no research exists confirming this to date.