Glioblastoma multiforme (GBM) is the most common of the aggressive primary brain tumours arising in adults and has a dire prognosis. Neuropsychiatric symptoms can vary significantly among afflicted persons; psychiatric disturbances may be the predominant presenting symptoms. Distinguishing between functional psychiatric disorders, particularly depression, from other subtle neuropsychiatric disturbances that may accompany GBM can be challenging. The authors present a clinical case and review of the literature in an attempt to highlight the special considerations that should be taken into account when evaluating patients who present with late-onset or atypical symptoms, refractory psychiatric symptoms, or subtle neurological disturbances signalling the need for diagnostic assessment, particularly neuroimaging, for the presence of a tumour. Early diagnosis is critical for improvement in quality of life.