DNA methylation-based measures of accelerated biological ageing and the risk of dementia in the oldest-old: a study of the Lothian Birth Cohort 1921

Table 1 Study sample demographics and univariate analyses

	Eligible Participants (n = 488)		Group Comparison p value (chi-square or t-test)	Excluded Participants (n = 62)
	Dementia (n = 109)	No Dementia (n = 379)	Group Comparison p value (chi-square or t-test)	Excluded Participants (n = 62)
Age	n = 109	n = 379		n = 62
-mean age in years (SD)	79.04 (0.55)	79.08 (0.59)	0.540	79.09 (0.53)
Sex	n = 109	n = 379		n = 62
% female	62.4%	55.9%	0.230	58.1%
Living or deceased	n = 109	n = 379		n = 62
% deceased	80.7%	87.3%	0.081	29.0%
MMSE score at baseline	n = 109	n = 379		n = 60
mean score (SD)	28.10 (1.64)	28.33 (1.46)	0.156	27.27 (2.67)
APOE ɛ4 carrier status	n = 109	n = 373		n = 61
% carrier APOE ɛ4	41.3%	22.5%	< 0.001	27.9%
Age 11 IQ (standardised)	n = 101	n = 339		n = 53
mean score (SD)	100.19 (16.18)	100.22 (14.53)	0.982	98.21 (15.63)
Smoking status	n = 108	n = 379		n = 62
% ever smoker	42.6%	61.7%	< 0.001	50.0%
Lifetime smoking packs^*	n = 108	n = 376		n = 58
mean total packs (SD)	4359.83 (8016.04)	6616.27 (8740.85)	0.016	3880.78 (6609.45)
History of hypertension	n = 108	n = 375		n = 61
% positive history	35.2%	41.9%	0.212	41.0%
History of diabetes	n = 109	n = 379		n = 62
% positive history	4.6%	5.8%	0.624	1.6%
History of cardiovascular or cerebrovascular disease	n = 104	n = 373		n = 59
% positive history	28.9%	28.2%	0.889	22%
EEAA	n = 88	n = 295		n = 53
mean (SD)	0.37 (7.27)	2.35 (8.41)	0.047	−0.27 (6.68)
IEAA	n = 88	n = 295		n = 53
mean (SD)	−0.64 (5.60)	0.80 (6.84)	0.074	0.59 (5.13)
AgeAccelGrim	n = 88	n = 295		n = 53
mean (SD)	−1.30 (4.14)	0.66 (4.64)	< 0.001	−0.39 (4.91)
AgeAccelPheno	n = 88	n = 295		n = 53
mean (SD)	0.21 (6.56)	1.75 (7.63)	0.087	0.53 (6.55)

Note.^*Lifetime smoking packs calculated by number of packs (20 cigarettes) smoked per year multiplied by the number of years smoking

ISSN: 1471-244X