Markers of inflammation and cognitive decline in an African-Caribbean population.
BACKGROUND
Inflammatory processes may play an important role in cognitive decline and dementia. We investigated the prospective association between levels of three markers of inflammation, plasma interleukin-6 (IL-6), serum C-reactive protein (CRP), serum amyloid A (SAA), and cognitive decline in an African-Caribbean community population.


METHODS
Of 290 participants aged 55-75 years at baseline sampled from Primary Care registration lists in south London, 216 (75%) were re-interviewed after 3 years. Baseline plasma concentrations of IL-6, CRP and SAA were ascertained through immunoassays. A battery of psychometric tests was administered on both occasions and decline in both individual tests and a composite outcome was analysed.


RESULTS
After adjustment for potential confounding factors, raised levels of IL-6 (>3.1 pg/ml) were associated with cognitive decline in the total sample (odds ratio 2.9, 95% CI 1.1-7.5), but no associations were found for CRP or SAA. Raised IL-6 was most strongly associated with decline in orientation and immediate verbal recall tasks, with weaker associations for delayed recall and psychomotor speed.


CONCLUSIONS
Raised IL-6 but not CRP predicted cognitive decline in this population Inflammatory changes associated with cognitive decline may be specific to particular causal pathways.
Jordanova
Vesna
V
King's College London, Institute of Psychiatry, London, UK.
Stewart
Robert
R
Davies
Emma
E
Sherwood
Roy
R
Prince
Martin
M
D000368:Aged; D015415:Biomarkers / Q000378:metabolism; D044383:Black People; D002097:C-Reactive Protein / Q000378:metabolism*; D017691:Caribbean Region / Q000208:ethnology; D003072:Cognition Disorders / Q000175:diagnosis* / Q000208:ethnology; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D015850:Interleukin-6 / Q000097:blood*; D008131:London / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D000685:Serum Amyloid A Protein / Q000378:metabolism*
D015415:Biomarkers; D015850:Interleukin-6; D000685:Serum Amyloid A Protein; D002097:C-Reactive Protein