There are various medical conditions, other psychiatric conditions and drug abuse related reactions that may mimic the symptoms of schizophrenia (meaning they have some or all of the same symptoms). For example, delirium can cause visual hallucinations, or an unpredictable changing levels of consciousness. Schizophrenia occurs along with obsessive-compulsive disorder (OCD), a disorder in which a person becomes obsessed with certain ideas or actions. However, separating the obsessions of OCD from the delusions of schizophrenia can be difficult.