If you would like to provide a medical diagnosis for patients upon examination (and/or their lab/test results), whether they have seizure disorder, mental disorder, leukemia and/or other illnesses, then perhaps medical school (D.O. or M.D.) is a route to consider. However, the medical student may need to do a clinical rotation in surgery and/or emergency medicine, for instance, which should be especially intense.
I'm not sure if you're wanting to do cognitive therapy, such as for those with Traumatic Brain Injury (TBI), stroke ("brain attack") - which is a type of brain injury - dementia/Alzheimers, or other such conditions that may affect cognition. If that's the situation, then perhaps looking into training to become a clinical neuropsychologist (PhD or PsyD) may be an option.
If you're considering getting schooling to provide cognitive therapy, perhaps you may consider job shadowing, especially at a *physical rehabilitation hospital*, which may have a program for people with Traumatic Brain Injury (TBI), stroke ("brain attack") - which is a type of brain injury - .and/or other neurological disorders (and may include those with seizure disorder).