Disentangling the Diagnoses of Psychotic Depression, Catatonia, Neurocognitive Disorders, and Delirium: A Multidisciplinary Approach

An ambiguous clinical presentation can create diagnostic uncertainty, leading to delays in effective interventions and increasing the likelihood of adverse clinical outcomes. Unfortunately, many psychiatric conditions share overlapping clinical symptoms. Psychotic depression, catatonia, neurocognitive disorders, and delirium are all examples of distinct clinical conditions with overlapping symptomatology, and all require decidedly different therapeutic interventions. While much literature is devoted to the diagnostic criteria and management of these clinical conditions, little is dedicated to the challenge of disentangling these diagnoses when faced with a complex clinical presentation.

We present here a complicated psychiatric inpatient hospitalization of a 77-year-old male who exemplified this diagnostic challenge. He primarily presented with severely depressed mood and decreased functionality, remaining in bed for much of the day with little attention to basic hygiene and oral intake. While records from a recent outside hospitalization carried a historical diagnosis of catatonia, his moderate level of engagement with providers and somatic delusion of disseminated prostate cancer suggested an alternate diagnosis of psychotic depression. However, before a diagnostic conclusion could be reached, other clinical characteristics surfaced. Following a singular administration of olanzapine shortly after his initial assessment, he developed Lilliputian hallucinations, prominent parkinsonism, and significantly altered mentation.

Neuroleptic sensitivity raised clinical suspicion for an underlying neurocognitive disorder such as dementia with Lewy bodies, and a consult was placed to the neuropsychology service. While dementia could not be fully ruled out, they did recommend additional workup to rule out herpes simplex encephalitis, autoimmune limbic encephalitis, and paraneoplastic syndromes. After his MRI imaging revealed moderate microvascular ischemic changes, a true multidisciplinary approach to care was taken, as neurology was consulted to also help narrow the differential. An EEG was unremarkable and a serum encephalitis panel was also unremarkable. Olanzapine was discontinued with significant improvement in parkinsonism and cognition; however, severe neurovegetative symptoms and somatic and nihilistic delusions persisted. While antipsychotics remained clinically indicated for a suspected depression with psychotic features, caution was taken due to established neuroleptic sensitivity, subtle catatonic features, and the related risks of neuroleptic malignant syndrome. Ultimately, low-dose quetiapine was initiated with some benefit; however, he continued to remain acutely depressed and withdrawn with prominent negativism. Trials with benzodiazepines for these catatonic features were also approached with caution to avoid potential risks of delirium.

Over time, a multidisciplinary approach to psychopharmacologic interventions and medication trials led the team to a principal diagnosis of major depressive disorder with psychotic features and subtle catatonia. The abrupt changes observed early in the hospital course were determined to be related to olanzapine-induced anticholinergic delirium. With greater diagnostic certainty, the team was able to counsel the patient and family about the importance of pursuing electroconvulsive therapy (ECT). The patient's cardiovascular risk factors and known microvascular changes were considered in the determination of the appropriateness for ECT. After starting ECT, he was immediately noted to have objective improvement, and following his fifth treatment, he was deemed appropriate for discharge after exhibiting significant improvement in depression and functionality and reporting near-resolution of somatic delusions. He was able to complete ECT on an outpatient basis and follow-up visits note durable improvements in mood, functionality, and quality of life, continuing to enjoy an active lifestyle of socializing with family and playing tennis. We use this case to further explore the clinical challenges that stem from the symptomatic similarity between psychotic depression, catatonia, neurocognitive disorders, and delirium and discuss optimal therapeutic approaches when the presentation appears complex and equivocal.