Prevalence and Features of Misdiagnosis of Primary Psychiatric Disorders Among bvFTD Patients

Objective: Previous studies have reported misdiagnosis rates of nondegenerative primary psychiatric disorders of up to 50% among patients with behavioral variant frontotemporal dementia (bvFTD). The authors hypothesized that misdiagnosis rates have decreased over time because of an increased awareness and a better understanding of psychiatric prodromes of FTD. Methods: Retrospective data on past psychiatric trajectories of individuals with probable or definite bvFTD (N=609) were acquired from 12 sites of the Neuropsychiatric International Consortium on FTD. Symptom profiles, primary psychiatric disorder diagnoses, and treatment information were collected from medical records. The authors used descriptive statistics to characterize past diagnostic trajectories, chi-square and t tests to compare groups, and logistic regressions to determine risk factors for diagnostic errors. Results: Of 609 bvFTD patients, 33% received a primary psychiatric disorder diagnosis after the onset of bvFTD symptoms but before a formal bvFTD diagnosis. In 13% (N=80) of all bvFTD cases, the diagnosis was retrospectively considered erroneous. The most common misdiagnosis was major depressive disorder, followed by anxiety disorders and psychosis. The remaining cases were classified as psychiatric prodromes (N=68) and comorbid conditions (N=42). Patients with misdiagnoses were significantly younger, by about 5.5 years, than those without such diagnoses and had higher rates of depressed mood, dietary changes, stereotypy, somatization, and anxiety symptoms. Only younger age predicted erroneous diagnoses. Conclusions: The rate of patients who were misdiagnosed as having primary psychiatric disorders was much lower than in previous reports, suggesting improvements in the quality of diagnostic assessments. Misdiagnoses were more common among younger patients, with some psychiatric symptoms being overrepresented in such cases.