Carotenoid levels in ageing human brain with reduced cognitive function

Abstract

While increased plasma carotenoid levels have been associated with protection of cognitive function in humans, only limited information is available on carotenoid levels in human brain tissues through ageing. To better understand if brain carotenoid profiles change as a result of enhanced aging and declined cognitive function, human brain tissues (frontal cortex) were collected and analyzed post‐mortem from young‐old (YO; n=15) (<85 years) and old‐old (OO; n=15) (>85 years) individuals defined with normal cognitive function (NCF), mild (MCI) or severe cognitive impairment (SCI). Lutein, zeaxanthin and β‐cryptoxanthin were predominant carotenoid species in brain tissues from both normal and cognitively impaired accounting for >70% of total carotenoid levels in brain tissues. Higher total carotenoid levels were observed in tissues from OO (347.1 pmol/g) compared to YO (147.8 pmol/g) subjects with normal cognitive function. Additionally, a marked decrease was observed in total carotenoid content of OO tissues from individuals with mild cognitive impairment relative to normal function (224.6 versus 347.1 pmol/g respectively). Carotenoid levels in both OO and YO brain tissues with severe cognitive impairment did not different from normal individuals. These data suggest that carotenoid levels in brain tissue may correlate with ageing and may decline with mild cognitive impairment. The clinical significance of these results and the extent to which these differences are associated with specific markers of cognitive function merits future consideration.