title: High Blood caffeine levels in MCI linked to lack of progression to dementia.
abstract: Although both human epidemiologic and animal model studies have suggested that caffeine/coffee protects against Alzheimer's disease, direct human evidence for this premise has been lacking. In the present case-control study, two separate cohorts consisting of 124 total individuals (65-88 years old) were cognitively assessed and a blood sample taken for caffeine/biomarker analysis. Subjects were then monitored for cognitive status over the ensuing 2-4 year period to determine the extent to which initial plasma caffeine/biomarkers levels would be predictive of changes in cognitive status. Plasma caffeine levels at study onset were substantially lower (-51%) in mild cognitive impairment (MCI) subjects who later progressed to dementia (MCI→DEM) compared to levels in stable MCI subjects (MCI→MCI). Moreover, none of the MCI→DEM subjects had initial blood caffeine levels that were above a critical level of 1200 ng/ml, while half of stable MCI→MCI subjects had blood caffeine levels higher than that critical level. Thus, plasma caffeine levels greater than 1200 ng/ml (≈6 μM) in MCI subjects were associated with no conversion to dementia during the ensuing 2-4 year follow-up period. Among the 11 cytokines measured in plasma, three of them (GCSF, IL-10, and IL-6) were decreased in MCI→DEM subjects, but not in stable MCI→MCI subjects with high plasma caffeine levels. Coffee would appear to be the major or perhaps only source of caffeine for such stable MCI patients. This case-control study provides the first direct evidence that caffeine/coffee intake is associated with a reduced risk of dementia or delayed onset, particularly for those who already have MCI.
authors.affiliation: Department of Pharmaceutical Science, University of South Florida College of Pharmacy, Tampa, FL 33620, USA. ccao@health.usf.edu
authors.forename: Chuanhai
authors.initials: C
authors.lastname: Cao
authors.forename: David A
authors.initials: DA
authors.lastname: Loewenstein
authors.forename: Xiaoyang
authors.initials: X
authors.lastname: Lin
authors.forename: Chi
authors.initials: C
authors.lastname: Zhang
authors.forename: Li
authors.initials: L
authors.lastname: Wang
authors.forename: Ranjan
authors.initials: R
authors.lastname: Duara
authors.forename: Yougui
authors.initials: Y
authors.lastname: Wu
authors.forename: Alessandra
authors.initials: A
authors.lastname: Giannini
authors.forename: Ge
authors.initials: G
authors.lastname: Bai
authors.forename: Jianfeng
authors.initials: J
authors.lastname: Cai
authors.forename: Maria
authors.initials: M
authors.lastname: Greig
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Schofield
authors.forename: Raj
authors.initials: R
authors.lastname: Ashok
authors.forename: Brent
authors.initials: B
authors.lastname: Small
authors.forename: Huntington
authors.initials: H
authors.lastname: Potter
authors.forename: Gary W
authors.initials: GW
authors.lastname: Arendash
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000544:Alzheimer Disease / Q000097:blood / Q000523:psychology; D002110:Caffeine / Q000097:blood*; D016022:Case-Control Studies; D003071:Cognition / Q000502:physiology*; D060825:Cognitive Dysfunction / Q000097:blood* / Q000523:psychology; D003704:Dementia / Q000097:blood / Q000517:prevention & control* / Q000523:psychology; D018450:Disease Progression; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009483:Neuropsychological Tests; D012307:Risk Factors
chemical_list: D002110:Caffeine