Early-onset Alzheimer disease: The contribution of neuroimaging for the diagnosis

The diagnosis of Alzheimer disease (AD) at an early age of onset may be a challenging task. The diagnosis of such a type of dementia may be even more difficult when concomitant depressive symptoms occur. We report the case of a 51-year-old woman who was admitted at a Psychiatric Day Hospital presenting with depressive symptoms, visuospatial deficits, apraxia, and minor memory loss. The patient underwent long-term antidepressant therapy, but despite the improvement of depressive symptoms, there was progressive cognitive deterioration. Otherwise, the prior clinical history was unremarkable, and there was no family history of dementia. The clinical examination revealed cognitive deficits in several domains. The patient scored 12 in the Mini-Mental State Examination. Routine laboratory tests were normal. Magnetic resonance (MR) imaging showed global brain volume loss more pronounced than would be expected for someone of the patient's age, especially in the precuneus a pattern of posterior cortical atrophy consistent with the diagnosis of early-onset AD. Images obtained with 99mTc-HMPAO single-photon emission computed tomography (SPECT) also revealed marked brain hypoperfusion involving the left parietal lobe, far beyond the regions of brain volume loss. This clinical case report illustrates the relative contribution of both MR imaging and SPECT for the diagnosis of dementia in a patient with concomitant depressive symptoms. Apart from contributing to the diagnosis of dementia beyond the traditional exclusionary approach, neuroimaging is increasingly being used to classify its particular subtypes. The role of neuroimaging role in AD is also supported by a recent proposal of revised diagnostic criteria, which take into account abnormal biomarkers of disease. Crown Copyright (C) 2010 Published by Elsevier Ireland Ltd. All rights reserved.