Even experienced professionals might minimise the prevalence of Attention Deficit Hyperactivity Disorder (ADHD) among certain groups of patients. Decreased attention, hyperactivity, and impulsivity are sensitive but non-specific behavioural patterns, frequently reported in a wide range of children and adults with different disorders. Therefore, the existence of ADHD might become transparent for both the patients and the professionals. Such transparency might lead to a non-accurate diagnosis, harm the treatment aspects and have potential non beneficial prognostic aspects. Among children and adults with mental retardation, autistic spectrum disorders, and drug abuse, as well as among gifted children, children with sensory modulation disorders, and children who were born IUGR, the diagnosis of ADHD might be very challenging. It seems that among these double-diagnosis populations there is a higher prevalence of patients with ADHD than in the general population, yet the exact prevalence, diagnostic difficulties and treatment methods have not been clearly estimated or established. It also seems that the percentage of ADHD among adolescents and children with chronic illness is still underestimated, since its clinical characteristics tend to be different. During the last years there have been growing numbers of publications in this field, but due to the wide range of interested professionals, these studies are published in a wide range of journals, usually missing some of their target populations. There is a lack of volumes gathering relevant data for a broad range of interested professionals from different specialties. The objective of this book is to serve as a useful tool for a wide range of professionals with a special interest in the unusual aspects of ADHD in order to increase their knowledge, sensitivity and treatment methods among our transparent patients.
