Delusional Misidentification Syndromes (DMS) are a group of rare psychiatric conditions where individuals mistakenly believe that a person, place, or object has been replaced or is someone else. Common forms include the Capgras delusion, where a person thinks a loved one has been replaced by an imposter, and the Fregoli delusion, where one believes that different people are actually a single person in disguise. These syndromes often occur in the context of other mental health disorders, such as schizophrenia or dementia. Treatment typically involves a combination of medication and psychotherapy to address the underlying conditions and help the individual regain a clearer perception of reality.