Implication of right frontostriatal circuitry in response inhibition and attention-deficit/hyperactivity disorder.

OBJECTIVE: To examine the relation between specific frontostriatal structures (prefrontal cortex and basal ganglia) and response inhibition deficits observed in attention-deficit/hyperactivity disorder (ADHD). METHOD: Children with ADHD and age-matched normal controls were scanned using magnetic resonance imaging (MRI) and tested on three response inhibition tasks. Behavioral performance was correlated with MRI-based anatomical measures of frontostriatal circuitry (prefrontal cortex and basal ganglia) implicated in ADHD. RESULTS: First, significant differences in performance by children with ADHD and normal volunteers were observed on all three response inhibition tasks. Second, performance on these tasks correlated only with those anatomical measures of frontostriatal circuitry observed to be abnormal in children with ADHD (e.g., the region of the prefrontal cortex, caudate, and globus pallidus, but not the putamen) in the authors' previous study. Third, significant correlations between task performance and anatomical measures of the prefrontal cortex and caudate nuclei were predominantly in the right hemisphere, supporting a role of right frontostriatal circuitry in response inhibition and ADHD. CONCLUSION: The data suggest a role of the right prefrontal cortex in suppressing responses to salient, but otherwise irrelevant events while the basal ganglia appear to be involved in executing these behavioral responses.

A Developmental Functional MRI Study of Prefrontal Activation during Performance of a Go-No-Go Task.

This study examines important developmental differences in patterns of activation in the prefrontal cortex during performance of a Go-No-Go paradigm using functional magnetic resonance imaging (fMRI). Eighteen subjects (9 children and 9 adults) were scanned using gradient echo, echo planar imaging during performance of a response inhibition task. The results suggest four general findings. First, the location of activation in the prefrontal cortex was not different between children and adults, which is similar to our earlier pediatric fMRI results of prefrontal activation during a working memory task (Casey et al., 1995). Second, the volume of activation was significantly greater for children relative to adults. These differences in volume of activation were observed predominantly in the dorsal and lateral prefrontal cortices. Third, although inhibitory processes have typically been associated with more ventral or orbital frontal regions, the current study revealed activation that was distributed across both dorsolateral and orbitofrontal cortices. Finally, consistent with animal and human lesion studies, activity in orbital frontal and anterior cingulate cortices correlated with behavioral performance (i.e., number of false alarms). These results further demonstrate the utility of this methodology in studying pediatric populations.

Ulcer risk factors: interactions between Helicobacter pylori infection, nonsteroidal use, and age.

PURPOSE: To evaluate the influence of Helicobacter pylori, nonsteroidal anti-inflammatory drug (NSAID) use, tobacco and alcohol use, age, gender, ethnic group, and the indication for endoscopy on the frequency of gastric and duodenal ulcers in patients referred for upper endoscopy. PATIENTS AND METHODS: One thousand eighty-eight consecutive patients without prior antrectomy or active bleeding at endoscopy who were able to provide a history were interviewed prior to endoscopy, and antral biopsies were performed for H. pylori at endoscopy. Variables were tested for univariate association with duodenal or gastric ulcer and those variables with p < 0.25 were included in the logistic regression model building. RESULTS: One hundred seven patients had duodenal ulcer, 97 had gastric ulcers, and 5 had both. Significant risk factors in the final model for duodenal ulcer were H. pylori, history of previous ulcer, male gender, bleeding, and pain at presentation (p < 0.001), whereas alcohol was associated with a decreased risk (p = 0.026). H. pylori presence (p = 0.011), aspirin use (p = 0.009), and bleeding (p = 0.012) were associated with gastric ulcer in the final model; esophageal symptoms were associated with decreased risk of gastric ulcer (p = 0.003). NSAID use was associated with gastric ulcers only in those over 55 (p < 0.05), especially whites, and in nonwhites without prior ulcer. There was no interaction between H. pylori and NSAIDs. CONCLUSIONS: H. pylori was associated with an increased risk of duodenal and gastric ulcers. Aspirin increases the risk for gastric ulcer in patients of all ages, whereas nonaspirin, nonsteroidal use increases the risk for gastric ulcers to varying degrees in patients over age 55, depending on race and history of ulcer.

Symptoms, gastritis, and Helicobacter pylori in patients referred for endoscopy.

Acute Helicobacter pylori infection is associated with dyspeptic symptoms but chronic infection has not clearly been shown to cause symptoms. To define further the role of H. pylori infection and gastritis in dyspepsia, we interviewed all patients about to undergo upper endoscopy, recorded the primary indication for endoscopy, noted the endoscopic findings, and obtained antral biopsies. Among non-ulcer patients there was a strong correlation of acute gastritis with H. pylori. Gastritis and H. pylori increased with age, and non-steroidal anti-inflammatory drug use correlated with normal histology. Neither H. pylori concentration nor gastritis grade correlated with gender, use of alcohol and tobacco, indication for endoscopy, or symptoms (epigastric pain, nausea, vomiting, bloating, belching, heartburn, halitosis, and flatulence).