Brain Alterations in non-medicated adult ADHD patients with comorbid cocaine dependence

     In lecture we learned that attention deficit/hyperactivity disorder is a developmental disorder characterized by a lack of dopamine with symptoms of inattentiveness and hyperactivity, as well as an impulsive nature.  Children and young adults with this disorder are at an increased risk of psychiatric disorders later on in life, including substance use disorders.  Within patients suffering from ADHD, those with substance use disorders have a greater degree of impulsivity and respond less to pharmacological treatments such as methylphenidate for cocaine dependence. 

     The article that I read concerns the first study that analyzes structural brain differences between unmedicated ADHD patients with and without comorbid cocaine dependence.  It was discovered that the main physiological differences among ADHD patients with and without this dependence was seen as reductions in grey matter in the cerebellum, occipital, and striatal brain regions.  The reduced striatal grey matter may reflect the changes in availability of dopamine transporters in this region of the brain present for interaction with such drugs as methylphenidate for treatment.  Two possible methods of improving the pharmacological outcomes in drug therapy have been presented with these findings that include treatments to restore striatal or dopaminergic brain structures, and medications that do not target dopamine structures but different ones in treating disorders.  The study goes to show that more research needs to be done with regards to this dependence with a larger sample of patients, including females that have ADHD and comorbid cocaine dependence.  It would also be interesting to compare their data with similar data from a group of cocaine dependent patients without a comorbid diagnosis of ADHD.  This data would address the specificity of the current study's results concerning the effects of cocaine use on brain structure.  Finally, depression scores and comorbid dependence of nicotine was not accounted for by the study, but studies on nicotine dependence report reduced grey matter volumes in the prefrontal cortex and cerebellar areas compared to non-smokers, areas that are not concerning ADHD patients with and without cocaine dependence.

Link to article:

http://www.ncbi.nlm.nih.gov.ezaccess.libraries.psu.edu/pubmed/23726981

http://ac.els-cdn.com.ezaccess.libraries.psu.edu/S0376871613001828/1-s2.0-S0376871613001828-main.pdf?_tid=c471a28e-d142-11e2-bece-00000aab0f01&acdnat=1370809727_cf5f81a254a59fafcd1f951bf240c32e