Attention is the ability to focus on the matter in hand. Concentration is the ability to maintain that focus. The ability to focus on a selected part of the information reaching the brain is important in many everyday situations e.g. when conversing in a noisy place. It is also important to be able to attend to more than one source of information at the same time, e.g. when conversing while driving a car. 

Attention and concentration may be impaired in a wide variety of psychiatric disorderes including depressive disorders, mania, anxiety disorders, schizophrenia and organic disorders. Therefore the finding of abnormalities of attention and concentration does not assist in diagnosis. Nevertheless, these abnormalities are important in management; e.g. they affect patient’s ability to give or recieve information when interviewed and can interfere with a patient’s ability to work, drive a car or take part in leisure activities.