C-reactive protein and familial risk for dementia: a phenotype for successful cognitive aging.
OBJECTIVE
Identifying phenotypes for successful cognitive aging, intact cognition into late-old age (>age 75), can help identify genes and neurobiological systems that may lead to interventions against and prevention of late-life cognitive impairment. The association of C-reactive protein (CRP) with cognitive impairment and dementia, observed primarily in young-elderly samples, appears diminished or reversed in late-old age (75+ years). A family history study determined if high CRP levels in late-old aged cognitively intact probands are associated with a reduced risk of dementia in their first-degree family members, suggesting a familial successful cognitive aging phenotype.


METHODS
The primary sample was 1,329 parents and siblings of 277 cognitively intact male veteran probands at least 75 years old. The replication sample was 202 relatives of 51 cognitively intact community-ascertained probands at least 85 years old. Relatives were assessed for dementia by proband informant interview. Their hazard ratio (HR) for dementia as a function of the proband's log-transformed CRP was calculated using the proportional hazards model.


RESULTS
Covarying for key demographics, higher CRP in probands was strongly associated with lower risk of dementia in relatives (HR = 0.55 [95% confidence interval (CI) 0.41, 0.74], p < 0.02). The replication sample relationship was in the same direction, stronger in magnitude, and also significant (HR = 0.15 [95% CI 0.06, 0.37], p < 0.0001).


CONCLUSIONS
Relatives of successful cognitive aging individuals with high levels of CRP are relatively likely to remain free of dementia. High CRP in successful cognitive aging individuals may constitute a phenotype for familial-and thus possibly genetic-successful cognitive aging.
Department of Psychiatry, Mount Sinai School of Medicine, New York, USA. jeremy.silverman@mssm.edu
Jeremy M
JM
Silverman
James
J
Schmeidler
Michal S
MS
Beeri
Clive
C
Rosendorff
Mary
M
Sano
Hillel T
HT
Grossman
José R
JR
Carrión-Baralt
Irina N
IN
Bespalova
Rebecca
R
West
Vahram
V
Haroutunian
D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000097:blood / Q000235:genetics* / Q000523:psychology; D002097:C-Reactive Protein / Q000378:metabolism*; D003071:Cognition; D003704:Dementia / Q000097:blood / Q000235:genetics* / Q000523:psychology; D005190:Family; D020022:Genetic Predisposition to Disease; D006304:Health Status; D006801:Humans; D008297:Male; D010641:Phenotype; D012306:Risk; D011795:Surveys and Questionnaires
D002097:C-Reactive Protein