Neuropsychological differentiation of late onset schizophrenia and frontotemporal dementia

Frontaltemporal dementia (FTD) and schizophrenia are characterised by disturbances in cognition, personality, behaviour, and social functioning often leading to a decline in activities in daily living. Deterioration of comportment and disturbances in attention are typical in both disorders and manifest behaviourally in terms of withdrawal, isolation, lack of volition, emotional unresponsiveness, and poverty of speech. Accordingly, the considerable overlap in behavioural expression between patients with schizophrenia and FTD makes a differential diagnosis difficult. This different diagnosis is especially difficult when the age of onset of schizophrenia is late (i.e., 45 +). The purpose of this study was to identify which neuropsychological tests best differentiate patients with late onset schizophrenia from patients with FTD. Hence, neurocognitive test results from a total of 12 patients with FTD and 32 patients with schizophrenia were analysed using test sensitivity statistics (i.e., Cohen's U2% overlap). The results support a test battery composed of the WAIS-R Vocabulary, Information, Digit Span, and Comprehension subtests, and the Hooper Visual Organisation test as being the most sensitive measures to diagnostic differentiation between patients with FTD and those with late onset schizophrenia.