DNA methylation in the APOE genomic region is associated with cognitive function in African Americans

BMC Medical Genomics

Table 1 Characteristics of African Americans from the GENOA study with cognitive and DNA methylation data^a

		Full analysis sample^b	Subset sample^c
		(N = 289)	(N = 247)
Age (years)		67.2 (7.1)	67.4 (6.8)
Sex (female)		207 (72%)	183 (74%)
Education	Less than high school degree	95 (33%)	83 (34%)
	High school degree / GED	81 (28%)	68 (27%)
	Beyond high school degree	113 (39%)	96 (39%)
Body mass index (BMI, kg/m²)		30.9 (6.0)	30.9 (6.1)
Current smoker		34 (12%)	29 (12%)
Diabetes		85 (29%)	70 (28%)
Hypertension		241 (83%)	205 (83%)
White matter hyperintensity (WMH, cm³)		12.0 (14.2)	11.9 (13.6)
APOE ε4 carrier		N/A	102 (41%)
APOE ε2 carrier		N/A	60 (24%)
Processing speed (DSST, symbols)^d		30.6 (13.2)	30.4 (13.2)
Category fluency (Animal Naming, words)^d		14.2 (4.4)	14.0 (4.2)
Letter fluency (FAS, words)^d		28.2 (11.5)	28.1 (11.5)
Learning (RAVLT, words)^d		38. 5 (9.7)	38.5 (9.5)
Delayed recall (RAVLT, words)^d		6.1 (3.6)	6.2 (3.6)
Concentration effectiveness (SCWT, items)^d		20.5 (9.1)	20.4 (8.9)
Global cognitive function		− 0.12 (0.95)	− 0.17 (0.94)

^aMean (standard deviation) or n (%) are presented
^bIn the full sample, sample sizes for the cognitive measures range from 243 to 289. A total of 232 participants had data for WMH
^cSubset sample consists of subjects with available genotype data
^dValues of cognitive scores are the numbers of symbols, words, or items completed within certain time limits as required by each test. For additional details, see Smith et al. [19]