Overview
There are many psychiatric diseases which, thankfully, are relatively uncommon but when present do cause physical illness as well as psychiatric symptoms.
Examples of such diseases include lupus, antiphospholipid syndrome, motor neurone disease, certain types of epilepsy, such as TLE (temporal lobe epilepsy) and acute infections of the brain such as meningitis and encephalitis. There are many many more.
Most of these conditions will first present to medical doctors but often the developing psychiatric problems will need referral to a neuropsychiatrist for assessment and management.