The association between attention deficit hyperactivity disorder severity and risk of mild traumatic brain injury in children with attention deficit hyperactivity disorder in the United States of America: A cross-sectional study of data from the National Survey of Children with Special Health Care Needs.

BACKGROUND: As children with attention deficit hyperactivity disorder (ADHD) have shown to be at higher risk of accidents and injury, one may assume that they may also bear a higher likelihood of mild traumatic brain injuries (mTBI). However, the current scientific evidence whether ADHD severity is associated with traumatic brain injuries is controversial. The objective of this study was too assess the association between the severity of ADHD and prevalence of mTBI in 0- to 18-year-old children with ADHD in the United States. METHODS: Cross-sectional study using secondary data gathered in 2009/10 from the National Survey of Children with Special Healthcare Needs. After excluding comorbidity and those with nonspecific attention deficits, the final study population consisted of 10,739 children with ADHD from 40,052 households. The main exposure variable was self-reported ADHD severity (mild, moderate, or severe). The main outcome was mTBI, defined as head injury, traumatic brain injury, and/or concussion). Covariates included age, gender and race, medication status. Unadjusted and adjusted logistic regression analysis were used. RESULTS: Children with more severe ADHD had consistently increased incidences of mTBI. Adjusted logistic regression analysis revealed a statistically significant association between severity of ADHD and occurrence of mTBI. The corresponding odds ratios were 1.57 (95% confidence interval (CI) [1.13, 2.18] for moderate, and 1.79 (95% CI [1.18, 2.72]) for severe ADHD, respectively, compared with mild ADHD. In males, children with moderate and severe ADHD had increased odds of mTBI. The corresponding odds ratio for mTBI in those with moderate ADHD was 1.60 (95% CI [1.07, 2.39]) and 1.86 (95% CI [1.15, 3.00]) for severe ADHD, respectively. No associations between severity and mTBI were found in girls. CONCLUSIONS: As ADHD severity was associated with incidence of mTBI, it is important to identify those who need increased attention and counselling to prevent injury.

Contribution of N-methyl-D-aspartate receptors to attention and episodic spatial memory during senescence.

A decrease in N-methyl-D-aspartate receptor (NMDAR) function is associated with age-related cognitive impairments. However, NMDAR antagonists are prescribed for cognitive decline associated with age-related neurodegenerative disease, raising questions as to the role of NMDAR activity in cognitive function during aging. The current studies examined effects of NMDAR blockade on cognitive task that are sensitive to aging. Young and middle-age rats were trained on the five-choice serial reaction time task (5-CSRTT) and challenged with MK-801 (0.025, 0.05, and 0.1mg/kg or vehicle). Attention deficits were apparent in middle-age and performance of young and middle-age rats was enhanced for low doses of MK-801 (0.025 and 0.05). The beneficial effects on attention were reversed by the highest dose of MK-801. Older animals exhibited a delay-dependent impairment of episodic spatial memory examined on a delayed-matching to place water maze task. Similarly, a low dose of MK-801 (0.05mg/kg) impaired performance with increasing delay and aged animals were more susceptible to disruption by NMDAR blockade. Despite MK-801 impairment of episodic spatial memory, MK-801 had minimal effects on spatial reference memory. Our results confirm that NMDARs contribute to rapidly acquired and flexible spatial memory and support the idea that a decline in NMDAR function contributes to the age-related impairments in cognition.