Attention-induced bifrontal cerebral hemodynamic changes in boys with attention deficit disorder measured by near-infrared-spectroscopy (NIRS)

Introduction: The aim of the study was to measure hemodynamic changes by means of NIRS in both prefrontal regions induced by a cognitive task in children with a developmental attention deficit disorder (ADD/ADHD) in comparison to normal controls.

Methods: A total of 11 boys with a mean age range from 9 to 11 years and a diagnosis of ADD/ADHD participated in the study and were compared with 9 healthy age- and sex-matched controls. A trail making test designed to connect numbers from 1 to 90 in four sets, was used to induce attention. Changes in oxygenated (O₂Hb), deoxygenated (HHb) hemoglobin, tissue oxygenation index (TOI) and cerebral blood volume (CBV) were measured by NIRS. The optodes were located bifrontal in position of Fp2/F4 and Fp1/F3.

Results: During the first test set, designed as a short attention task, children with ADD showed a significant increase in O₂Hb and CBV, whereas the controls showed no significant change. During the four test cycles, which demanded extended attention, both groups showed an increase in O₂Hb and CBV. Only the controls showed an increase in HHB in the left prefrontal region. In the ADD/ADHD group an increase in TOI was documented in the left side.

Conclusions: Normal controls showed a lateralized oxygen consumption in the left prefrontal cortex during an extended attention task, whereas the boys with ADD showed an imbalance between oxygenated and deoxygenated hemoglobin during the short and extended attention task.

Keywords: near-infrared spectroscopy, attention deficit disorder, attention-induced cerebral hemodynamic changes