Academic and workplace difficulties can have many, many causes, which can overlap and may even change in importance or severity over time.   ADHD and learning disabilities, such as Dyslexia, are well-known causes of learning challenges in school, at all levels of education, and can cause difficulties in the workplace as well.  However, emotional distress (due to trauma, life events, family difficulties, or stressful circumstances beyond anyone's control), medical conditions (such as sleep difficulties, metabolic disorders, seizure disorders, and many others), concussions/head injuries, and developmental delays of various types can all cause academic and workplace difficulties as well.  To complicate things further, different people with the same underlying issue can have very different difficulties in school or work settings.  Just testing for one thing (ADHD, Dyslexia, etc.) is far too likely to miss important information, and undermine the effectiveness of intervention.  A full evaluation is critical.