Elevated parathyroid hormone levels and cognitive function: A systematic review.

• Hyperparathyroidism patients reported poorer cognition compared with controls. • Limited data presented the association between elevated PTH levels and cognition. • Identified studies show mixed results to support an association between PTH and cognition. • High-quality studies are needed to improve the evidence base. To systematically estimate the association between elevated parathyroid hormone (PTH) levels and cognitive function. This review was conducted on ten papers identified through database searches from inception to 31 October 2018. The quality of studies was assessed using the Downs and Black checklist. There is a low volume of data reporting on the impact of elevated PTH levels on cognitive impairment. The quality of the identified studies ranged from poor (37 %) to good (76 %). Although the results from studies were mixed, one cross-sectional study and one prospective study suggested a link between elevated PTH levels and a decrease in the Mini-Mental State Examination (MMSE) score. Three cross-sectional studies that assessed other cognitive domain in specific domains, such as language, memory and executive function provided mixed results for an association between elevated PTH levels and cognitive function. Two studies showed mixed evidence for a link between elevated PTH levels and poor executive function. One prospective study, one cross-sectional study and three case-control studies provide mixed evidence for an association between higher PTH levels and Alzheimer´s disease (AD). Two studies showed limited evidence for an association between elevated PTH levels and vascular dementia. This review presented that the level of evidence available to support an association between elevated PTH levels and cognitive function was generally weak and inconsistent. Future studies with more better methodological quality are needed. [ABSTRACT FROM AUTHOR]