Recent Research in ADHD
by Jay D. Tarnow, M.D.
In this month's Psychopharmacology Corner I am trying out a new format. I will report on the most up to date research articles that I feel adds to our understanding and treatment of ADHD. Please give me feedback at This email address is being protected from spambots. You need JavaScript enabled to view it..
The Neuroscience of ADHD
Previous research has identified abnormalities in volume, gray matter density, and thickness in areas such as the prefrontal cortex and striatum in persons with ADHD. A new novel study identified local surface changes in the thalamus of children with ADHD. Additionally, the study also identified a significant volume loss in the region of the pulvinar nuclei bilaterally. It was noted that these surface changes did not lead to a change in the overall thalamic volume in youths with ADHD compared to those with no ADHD. Additionally, youth with ADHD who were on medication had thalamic surface morphology more closely resembling those with no ADHD and thalamic volumes tended to be larger than those of unmedicated youth with ADHD.
Do Pesticides Cause ADHD?
A recent study conducted by the Departments of Environmental Health and Epidemiology and Harvard University School of Public Health examined the link between urinary concentrations of dialkyl phosphate (DAP) metabolites of organophosphates and pediatric ADHD.
According to the National Academy of Sciences, children between 6 and 11 years of age have the highest urinary concentrations of DAP metabolites compared with other age groups. The major source of exposure to organophosphates pesticides for infants and children is diet.
Cross-sectional data from the National Health and Nutrition Examination Survey was used to compare exposure to pesticides and the prevalence of ADHD. Six urinary DAP metabolites (resultant of the degradation of more than 28 different organophosphates) were measured in urine to provide an indicator of the body burden of common organophosphates.
A structured interview with a parent was used to ascertain an ADHD diagnosis. Around 12% of the children met the diagnostic criteria for any ADHD subtype. Most children had less than 1 detectable metabolite, of the 6 DAP measured. Children with higher urinary dialkyl phosphate concentrations were more likely to be diagnosed as ADHD. For the most-commonly detected DMAP metabolite (dimethyl thiophosphate), children with levels higher than the median of detectable concentrations had twice the odds of ADHD compared with children with undetectable levels. There was a 55% to 72% increase in the odds of ADHD for a 10-fold increase in DMAP concentration. It should be noted that these findings do not indicate a causal relationship between ADHD and DMAP concentration. Moreover, this study utilized the collection of only 1 urine test. Further tests will be able to better identify patterns of chronic exposure in children with ADHD.
The Quest for Nonpharmocologic Intervention Continues
There are several ADHD treatment options available today. Because initial improvements of ADHD symptoms are difficult to sustain, a lot of families look for non-medication treatments.
In a study conducted in Germany, children with ADHD not receiving medication were assigned to either a combined neurofeedback intervention or an attention skills training program. In neurofeedback, brain wave patterns (via electroencephalogram) are recorded during repetitive training and positive reinforcement. These are intended to produce and reinforce brain electrical activity.
It was found that the 51% of the children who received neurofeedback intervention responded to treatment vs. 29% of the children in the attention control condition. However, this outcome was not statistically significant due to small sample size and lack of sufficient controls.
It is advisable for families to know that there are effective treatment options available for patients. Neurofeedback may be successful for some individual cases but time and financial costs are primary risks.
How does foster care affect ADHD symptoms?
A recent study in New York examined the effects of biological parents as well as foster parents' warmth and hostility and the number of foster-home moves and discharges on ADHD symptoms.
It was found that children who received lower parental warmth (foster parent), higher parental hostility (biological parents, foster parents, and teacher) and discharge from care (biological parent) had higher inattentive symptoms. Children who received lower parental warmth (foster parent), higher parental hostility (biological parents and foster parents), higher number of foster-home moves, and discharge from care had higher hyperactivity.
This study was interesting because it examined ADHD symptoms in foster care settings. It was found that factors such as caregiving conditions can affect symptoms and that higher parental warmth and lower hostility from parents can influence symptoms in a positive manner.
The Long-Term Risks for Girls with ADHD
In a longitudinal case study of girls between the ages of 6 to 18 years, with and without ADHD, a reassessment was made after 11 years.
Subjects were blindly assessed with structured diagnostic interviews. It was found that girls with ADHD were at a high risk for psychiatric comorbidities, including substance use, mood and anxiety disorders, and eating disorders as they developed into young adults.
This study offers great insight into outcomes for girls with ADHD and the findings are in line with previous reports on boys with ADHD. This study is unique because it is one of the few longitudinal studies and the first to have followed young girls into
adulthood. This study emphasizes the need for clinicians to monitor both boys and girls with ADHD over time to assess for the emergence of psychopathology and associated at-risk behaviors.
ADHD and Risk for Hand Fractures
A recent review examined 208 pediatric patients treated at a trauma center. It was found the metacarpal fractures were the most common hand fractures seen in patients with a psychiatric history. Moreover, it was found that over 50% of the patients with a psychiatric diagnosis had a subsequent injury as compared to 15% of patients who did not have a psychiatric diagnosis but had a subsequent injury. The most common psychiatric disorders were ADHD, depression, and substance abuse. It was also found that psychiatric diagnosis was significantly more frequent when the injury was related to punching as opposed to some other action or reason. The researchers noted that the link between hand fractures and ADHD in these children is critical to consider the risks associated with this population. Such injuries may be prevented with appropriate identification, education, and treatment of psychopathology. Here is another example of the side effects of not using medication to treat ADHD.