Neuropsychological profile of prodromal Alzheimer's disease (Prd-AD) and their radiological correlates

Abstract

This study describes the cognitive profile of Prd-AD, the neuropsychological tests that may predict progression to dementia, and to study their brain structural correlates. We enrolled 24 stable amnesics who did not develop dementia after two years follow-up; 27 patients were considered as Prd-AD, in the initial visit, since they fulfilled NINCDS-ADRDA criteria after two years; 31 Alzheimer's disease (AD) patients and 27 controls (CTR). Structural magnetic resonance imaging (MRI), as well as a neuropsychological battery was performed at the initial visit. The key findings were: Prd-AD patients were characterized by prominent episodic memory dysfunction and minimal semantic memory and executive dysfunction. Semantic fluency test (Sem-Flu), delayed text memory test (Del-text-mem) and memory alteration test (M@T) (including both episodic and semantic memory), together with trail making test A (TMT-A), resulted significant predictors for dementia development in this group of amnesic patients. This optimal predictive model obtained an estimated accuracy of 53% after two years follow-up. M@T and semantic Sem-Flu test performance presented high correlation with decreased gray matter density in the left lateral temporal lobe. We conclude that Prd-AD is characterized by prominent episodic memory dysfunction and minimal semantic memory and executive dysfunction which are related with left medial, inferior and lateral temporal density loss, predominantly in the left side.