Using positron emission tomography and [18F]-2-fluoro-2-deoxy-D-glucose, the authors determined cerebral metabolic rates for glucose (CMRglc) in 39 adults (18-51 years old) with attention-deficit/hyperactivity disorder (ADHD) and 56 healthy control adults (19-56 years old) during the performance of a continuous attention task. Increased age was associated with reduced global CMRglc in ADHD women, but not in ADHD men, control men, or control women. Better performance on the attention task was significantly associated with increased age only in the ADHD female group. Determining the role of behavioral, hormonal, and genetic factors is a challenge for future research.