Addiction may involve the use of alcohol, drugs, nicotine or gambling. People who struggle with addiction pursue the behaviour despite the consequences, in order to experience the high or euphoria it brings them.

Attention deficit hyperactivity disorder (ADHD) causes people to have difficulty focusing or sitting still. Commonly diagnosed in children and teens, it also involves impulsive behaviour and hyperactivity.

Anxiety disorder causes people to intermittently feel nervous, have a sense of impending doom or danger, sweat, hyperventilate or experience an elevated heart rate. Many people with anxiety disorder have panic attacks.

Bipolar disorder, also known as manic-depressive illness, causes a periodic cycling of manic (heightened emotions and extreme activity) and depressive phases (sadness and lethargy).

Depression refers to a number of conditions that negatively affect how you think, feel and act. Many people with depression lose interest in activities and withdraw from others.