The clinical differentiation of fronto-temporal dementia from psychiatric disease

OBJECTIVE Frontal and/or temporal lobar atrophy (F/TA) is sometimes detected on neuroimaging in patients with psychiatric disease. This observation leads to difficulty in distinguishing whether patients have fronto-temporal dementia (FTD) or psychiatric illness. This paper sets out to develop clinical profiles that might be useful at first presentation to distinguish these two populations. METHODS 29 patients were selected from a database of 250 current patients attending young onset dementia clinic. Control and experimental patient groups were established using DSM-5 criteria: (i) those without selective atrophy who had a psychiatric disorder (N = 5); (ii) patients who had FTD using consensus criteria (N = 13); and (iii) an experimental group of patients who had F/TA on neuroimaging, a psychiatric diagnosis and referral with possibility of a neurodegenerative disorder (N = 11). Profiles suggestive of FTD and psychiatric disease were established in the control groups utilising information from medical records, the neurological examination, the natural history and neuropsychometry to develop criteria to distinguish reliably FTD from psychiatric disease. These criteria were then applied to the experimental group. Patients were followed for five years. RESULTS The developed criteria resulted in 3 patients being classified as FTD and 8 having psychiatric diagnoses in the experimental group. At follow-up, all the psychiatric patients remained functionally stable, whereas the FTD patients had deteriorated. CONCLUSION Characteristic profiles may prove useful in the diagnosis of patients with F/TA on imaging with a psychiatric illness and help to distinguish them from patients with FTD. At first presentation F/TA has been found in some patients with psychiatric disease who do not develop evidence of neurodegeneration. This suggests that F/TA on neuroimaging might be a feature of a subgroup of patients with psychiatric diseases.