The relationship between cerebrospinal fluid tau markers, hippocampal volume, and delayed primacy performance in cognitively intact elderly individuals

BACKGROUND: Primacy performance in recall has been shown to predict cognitive decline in cognitively intact elderly and conversion from mild cognitive impairment to Alzheimer's disease (AD). Delayed primacy performance, but not delayed nonprimacy performance, has been shown to be associated with hippocampal volume in cognitively intact older individuals. Because presence of neurofibrillary tangles is an early sign of AD-related pathology, we set out to test whether cerebrospinal fluid (CSF) levels of tau had an effect on delayed primacy performance, while controlling for hippocampal volume and CSF amyloid-β 1-42 levels. METHODS: Forty-seven individuals, aged 60 years or older and cognitively intact, underwent a multisession study including lumbar puncture, a magnetic resonance imaging (MRI) scan of the head, and memory testing. RESULTS: Our regression analyses show that CSF levels of hyperphosphorylated (P) tau are only associated with reduced delayed primacy performance when hippocampal volumes are smaller. CONCLUSION: Our findings suggest that hippocampal size may play a protective role against the negative effects of P tau on memory.