Difficulty concentrating, being easily distracted, being unable to stay focused on one activity at a time or the inability to complete tasks may be a sign that you struggle with Attention Deficit Hyperactivity Disorder (ADHD). While these symptoms may be due to another condition such as depression or anxiety, ADHD can co-exist with depression and/or anxiety and worsen the symptoms of these conditions. The diagnosis of ADHD is based on family history, your experience in school as a child, current symptoms, and neuropsychological testing.