Patients with methamphetamine abuse/dependence often exhibit high levels of impulsivity, which may be associated with the structural abnormalities and functional hypoactivities observed in the frontal cortex of these subjects. Although near-infrared spectroscopy (NIRS) is a simple and non-invasive method for characterizing the clinical features of various psychiatric illnesses, few studies have used NIRS to directly investigate the association between prefrontal cortical activity and inhibitory control in patients with methamphetamine-induced psychosis (MAP). Using a 24-channel NIRS system, we compared hemodynamic responses during the Stroop color-word task in 14 patients with MAP and 21 healthy controls matched for age, sex and premorbid IQ. In addition, we used the Barrett Impulsivity Scale-11 (BIS-11) to assess impulsivity between subject groups. The MAP group exhibited significantly less activation in the anterior and frontopolar prefrontal cortex accompanied by lower Stroop color-word task performance, compared with controls. Moreover, BIS-11 scores were significantly higher in the MAP group, and were negatively correlated with the hemodynamic responses in prefrontal cortex. Our data suggest that reduced hemodynamic responses in the prefrontal cortex might reflect higher levels of impulsivity in patients with MAP, providing new insights into disrupted inhibitory control observed in MAP.

The stimulant methylphenidate (MPH) and the nonstimulant atomoxetine (ATX) are the most commonly-prescribed pharmacological treatments for attention deficit/hyperactivity disorder (ADHD). However, the drug-specific mechanism of action on brain function in ADHD patients is not well known. This study examined differences in prefrontal hemodynamic activity between MPH and ATX in children with ADHD as measured by near-infrared spectroscopy (NIRS) using the Stroop color-word task.

Recent developments in near-infrared spectroscopy (NIRS) have enabled the non-invasive elucidation of the neurobiological underpinnings of psychiatric disorders. Functional neuroimaging studies in human patients have suggested that the frontal cortex and subcortical structures may play a role in the pathophysiology of obsessive-compulsive disorder (OCD). Here we used NIRS to investigate neurobiological function in 12 patients with OCD and 12 age- and sex-matched, healthy control subjects. The relative concentrations of oxyhemoglobin (oxy-Hb) were measured with prefrontal probes every 0.1 s, during performance of a Stroop color-word task, using 24-channel NIRS. Oxy-Hb changes in the prefrontal cortex of the OCD group were significantly smaller than those in the control group, especially in the left lateral prefrontal cortex. These results suggest that patients with OCD have reduced prefrontal hemodynamic responses as measured by NIRS.

Tourette's disorder (TD) is a chronic childhood-onset disorder characterized by the presence of multiple motor and vocal tics. Despite strong evidence that the pathophysiology of TD involves structural and functional disturbances of the basal ganglia and cortical frontal areas, in vivo imaging studies have produced conflicting results. Recent developments in near-infrared spectroscopy (NIRS) technology have enabled noninvasive assessment of brain function in people with psychiatric disorders.

Functional neuroimaging studies suggest that prefrontal cortex dysfunction is present in people with autism spectrum disorder (ASD). Near-infrared spectroscopy is a noninvasive optical tool for examining oxygenation and hemodynamic changes in the cerebral cortex by measuring changes in oxygenated hemoglobin.