About two years ago, my GP diagnosed me with ADHD. He wanted to put me on Concerta, but I opted for Strattera instead, out of fear of addiction. The Strattera did help somewhat.
Eventually I went to see a psychiatrist. He said that I did not have ADHD, and instead diagnosed me with depression. My mental problems, such as poor concentration, poor memory, and distractability, were due to depression. To be certain, he also referred me to an occupational therapist for an ADHD assessment, which took almost an entire day. They confirmed that I did not have ADHD.
The antidepressant medication that I am on, has worked wonders and has completely restored my cognition.