Neurofeedback (NF) is based on brain imaging studies, quantitative electroencephalography (qEEG), positron emission tomography and single photon emission computed tomography (SPECT), which all show cortical brainwave slowing in the majority of attention deficit hyperactivity disorder (ADHD) patients, as well as too much or too little coherence across functional areas of the brain. Evoked potentials too, reveal subtypes of ADHD, which are known as endophenotypes and will influence the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM–V), due to be published in 2011.