The two main syndromes of Attention-Deficit / Hyperactivity Disorder (AD/HD) are (1) inattentiveness and (2) hyperactivity/impulsivity which may lead to children having significant functional problems in learning and interpersonal relationships, emotional problems or low self-esteem. Manifestations of the symptoms in children, adolescents and adults may appear different. The common attentional problems of these children may include difficult to sustain attention and remain engaged in an activity, easily distracted by the environment, inattentive and seemed not to listen, difficult in following through on instructions, completing tasks and organizing activities, forgetful and often losing or forgetting to bring their personal belongings. Their hyperactive/impulsive problems may include often moving about and becoming fidgety when expecting to stay still for extended time, difficult to stay seated when required, often leaving or squirming in their seats, excessive talking, difficult in engaging in activities quietly, tending to be impatient and impulsive, having difficulty queuing or waiting for their turn, tending to interrupt or blurt out answers before the questions are completed or cannot wait for their turn. In the period of late childhood and early adolescence, the severity of hyperactivity may decline though features of inattention and impulsivity often remain. Some potential problems may appear such as frequent engagement in interpersonal conflict, fighting or substance use. Adults with AD/HD may have difficulty in their concentration at work, as well as symptoms of distractibility, disorganization, inefficiency, impatience or impulsivity. Psychologists would use standardized assessment tools and face-to-face interviews to understand the specific situation of the clients.