Snapshot A 25-year-old woman is referred to a psychiatrist by her primary care provider due to concerns that she is having "persistent beliefs" that may need further clinical assessment. The patient believes that she is the editor-in-chief of Time magazine and states that anyone who believes otherwise is "missing the truth." She becomes irritated when pressed on specific details of her job or whether she can prove her role. Collateral information reveals that the patient works as a waitress at a local cafe. The patient is alert and oriented on mental status exam. A urine toxicology screen comes back negative. Introduction Overview delusional disorder characterized by > 1 month of delusions without other psychotic symptoms Epidemiology Prevalence 0.02% in the US Demographics mean age of onset is 40 years females > males ETIOLOGY Pathophysiology unknown may involve biochemical and psychological factors Associated conditions shared psychotic disorder (folie à deux) development of delusions in a person in a close relationship with someone with delusional disorder often resolves upon separation delusional parasitosis fixed, false belief that the individual is infested with insects, bugs, parasites, or some other organism may experience formication absence of physical exam findings Presentation Symptoms delusions false beliefs based on incorrect inference about reality typically non-bizarre (i.e., unlikely but possible) patient typically lack insight to the fact that their beliefs are delusions types of delusions include persecutory belief one is going to be harmed referential belief that certain gestures, comments, or environmental cues are directed at oneself grandiose belief that the individual has exceptional abilities, wealth, or fame nihilistic conviction that a major catastrophe will occur somatic beliefs focused on bodily function or sensation erotomanic false belief that another individual is in love with them Physical exam criteria for diagnosing delusional disorder presence of 1 or more delusions for > 1 month the criteria for schizophrenia has never been met before functioning is not markedly impaired if manic or major depressive episodes have occurred, these have been brief relative to the duration of the delusional periods the disturbance is not better explained by another mental disorder (i.e., OCD) or substance use disorder normal cognitive function Differential Delirium key distinguishing factors fluctuating level of consciousness, altered sleep/wake cycle, hallucinations, and impaired cognition Dementia key distinguishing factor impaired cognition Schizophrenia key distinguishing factor disorganized thought process, speech, or behaviors Body dysmorphic disorder key distinguishing factor obsessive focus on perceived flaw in appearance and excessive attempts to fix the flaw Treatment Lifestyle cognitive-behavioral therapy supportive therapy to educate patients about the illness and social skills training (i.e., not discussing delusional beliefs in public) Medical antipsychotics (i.e. aripiprazole and ziprasidone) first-line treatment of delusional disorder requires significant effort to provide information about the medication, the side effects, and length of treatment patient denial and lack of insight may present as obstacles to treatment