The prevalence of fragile X syndrome, velocardiofacial syndrome (VCFS), and other cytogenetic abnormalities among 100 children (64 boys) with combined type ADHD and normal intelligence was assessed at the NIMH and Georgetown University Medical Center. One girl with ADHD had a sex chromosome aneuploidy (47,XXX); 1 boy had a premutation-sized allele for fragile X and none showed the full mutation. Testing for 22q11.2 microdeletion characteristic of VCFS was negative for all subjects screened. The results were not different from those expected by chance. Prevalences exceeding 5.5% for chromosomal abnormalities, 3.7% for VCFS, and 3.6% for fragile X full mutations were excluded. In children with ADHD and normal intelligence with no clinical signs and absent family history of chromosome anomalies, testing for cytogenetic abnormalities is not warranted. 
COMMENT. In the absence of clinical indications, including developmental delay, physical signs, or positive family history, testing for chromosomal abnormalities, VCFS, or fragile X is not indicated in children with ADHD of normal intelligence.
Cigarette smoking in adolescents with ADHD. Cigarette smoking was associated with family and peer smoking and with clinically significant ADHD inattention symptoms in a confidential self-report survey of 1066 tenth-grade students in five public high schools conducted at the Lombardi Cancer Center, Washington, DC. ADHD inattentive type is a significant risk factor for cigarette smoking in adolescents. 
Altered cortical activity in ADHD during attentional load task is demonstrated by quantitative electroencephalography performed with eyes open and during Continuous Performance Task. Increased slow activity over frontal areas and decreased fast cortical activity were observed, indicating a different arousal pattern and possible delay in cortical maturation.