Low Serum Phosphorus Correlates with Cerebral Aß Deposition in Cognitively Impaired Subjects: Results from the KBASE Study.

ABSTRACT

Alzheimer's disease (AD), characterized by progressive cognitive decline, is the most prevalent neurodegenerative disease in the elderly. Cerebral ß-amyloid (Aß) deposition is the major pathological hallmark of AD. Recent studies also have shown that the serum level of phosphorus correlates to the risk of incident dementia. To date, the linkage between cerebral Aß deposition and the serum phosphorus level remains unknown. In this study, we analyzed the levels of serum phosphorus in 109 mild cognitive impairment (MCI) and 73 AD dementia (ADD) subjects. All subjects underwent Pittsburgh compound B positron emission tomography (PiB-PET) imaging to measure cerebral Aß deposition. The results with Aß deposition was compared with the serum levels of phosphorus. The subjects with cerebral Aß deposition showed lower levels of serum phosphorus than those without Aß deposition. Furthermore, multiple regression analyses showed that a low level of serum phosphorus correlated with cerebral Aß deposition, even when age, sex, apolipoprotein E ε4 genotype, and MMSE z-score were controlled for. Serum levels of other ions, including calcium, iron, zinc, and copper, showed no such correlation. In conclusion, our results suggest that the serum level of phosphorus may be used as an easily accessible blood biomarker for cerebral Aß deposition in a cognitively impaired population.