Attention deficit hyperactivity disorder (ADHD) is one of the most common childhood behavioral disorders. ADHD can also affect adults. Patients with ADHD may be impulsive, hyperactive and have trouble focusing. While many people sometimes experience ADHD symptoms, those who are diagnosed with the disorder have these symptoms frequently for six months or longer. While diet changes may help these patients, poor diet and eating habits do not cause ADHD. An ADHD-friendly diet may also not be enough to completely manage the symptoms of the disorder. Talk to your doctor before starting any new diet.