Attention deficit disorder is widely recognized in children but underdiagnosed in adults. It is believed that adult hyperactivity is caused by underactivity in one part of the brain, possibly due either to genetic dysfunction or fetal exposure to environmental toxins such as lead, alcohol or cigarettes. ADD can be treated with amphetamine-like drugs to stimulate the brain, which damps down the physical overactivity.
Symptoms of the condition in adults include: an irritable, moody, unpredictable and impatient personality; an intrusive and impulsive behaviour style; difficulty with rules and authority, poor communication skills, intolerance to noise, and inability to handle interruptions. In the USA it is believed that up 60% of children retain hyperactivity traits when they grow older, and can affect as many as 1 in 1,000 people. They are perceived as having personality disorders rather than a medical problems that may be alleviated with drugs. They are often very intelligent but give the impression of being unmotivated and feckless ne'er do-wells.
2. American companies were beginning in 1997 to receive disability claims for ADD, and are concerned about the potential for fraud, as the symptoms are easy to fake.