MEDICAL MIMICS: DIFFERENTIAL DIAGNOSTIC CONSIDERATIONS FOR PSYCHIATRIC SYMPTOMS

Although diagnosing mental illness can be challenging, mental health clinicians too often make reckless misdiagnoses. The consequences of misdiagnosis are wide-ranging, all of which include poor outcomes for patients. Clinicians need to return to simple, ethical best practices to solve this prolific problem.

Years of misunderstanding and over-diagnosing mental illness has led to many taking psychiatric medications they don’t need. The result has been children, adolescents and adults failing to learn appropriate coping and problem solving skills to manage life after medicating away normal emotions.

Patients with underlying medical disease can present to the health care system with psychiatric symptoms predominating. Identification of an underlying medical condition masquerading as a psychiatric disorder can be challenging for clinicians, especially in patients with an existing psychiatric condition. There is no single test, examination, or procedure to easily and effectively differentiate primary versus secondary psychosis on the basis of presenting psychopathology alone. The general terms medical mimic or secondary psychosis have been used to describe this clinical situation. Although certain presenting signs and symptoms may be suggestive of a medical mimic, there is no clear-cut constellation of pathognomonic signs and symptoms to guide the clinician to the correct diagnosis. In older literature, the term organic cause referenced a physical or physiologic change to some tissue or organ of the body; however, this term has fallen out of favor. The term secondary psychosis generally applies to a psychotic disorder arising from substance abuse or a preexisting physical health diagnosis. The Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5), addresses this phenomenon via two diagnostic categories: substance-induced disorders, which includes medications, and unspecified mental disorder due to another medical condition in situations where the clinician may lack needed information for a complete diagnosis. In both of the DSM-5 diagnostic categories, the individual may present with symptoms of delusions and/or hallucinations, while the broader interpretation of medical mimics may include other psychiatric symptoms, such as depression, confusion, or mood lability. Overall crucial assessment procedures are less likely to be performed if the patient is admitted to a psychiatric service than if he or she is admitted to a medical service.5 Symptoms in patients with a history of mental illness are more likely to be attributed to psychiatric illness than those of patients without such a history. Of note, there is a relative dearth of published literature on this topic, and most published reports predate the publication of the DSM-5 in 2013.

Hallmark signs and symptoms of a medical mimic include one or more features that are atypical for the psychiatric symptoms. These comprise, but are not limited to, normal functioning prior to onset, unusual age at onset, and/or paroxysmal onset. Other elements to consider in the evaluative process include the presence or absence of a prior personal or family history of mental illness, recent substance abuse, prescription medication use (new medication, recent dosage change, unreported overuse or abuse), waxing and waning mental status change, treatment resistance, or any unusual response to treatment.1 Groups considered to be at higher risk for medical illness presenting with psychiatric symptoms include the elderly, patients with a history of substance abuse disorder(s), patients without a prior history of psychiatric illness, patients with preexisting medical illness, and patients from lower socioeconomic strata.

It is clear that initial misdiagnosis can lead to a variety of issues, including unnecessary or harmful treatment, unintended delay in treatment, increased length of hospitalization, and increased costs to the health care system and payers. Diagnoses traditionally are based on the clinical features observed at the time of presentation to the health care system. In general, these observed clinical features are consistent with the known body of literature for symptoms classification of disorders or disease states (ie, rule in or rule out based on the clinical presentation and initial evaluation results).7 In persons with a history of mental illness, there may be the potential to attribute observed symptoms to that mental illness before doing a thorough medical evaluation. Therefore, a careful and consistent evaluation framework may improve the larger body of information that informs the interpretation of the clinical presentation and minimizes initial misdiagnosis.

The purpose of the present work is to provide a clear, comprehensive, and structured process for consideration in evaluating and assessing a patient with an acute psychiatric presentation. Differentiating primary from secondary psychosis is critical in order to minimize the risk of overlooking and addressing an underlying medical issue that may be causal.

Medical mimics: Differential diagnostic considerations for psychiatric symptoms: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6007536/?fbclid=IwAR0crEwfApENQqm5ucUn0jcEGT4zIHwZcAmbamIfAfuujYgiKKUdKAVTOBM