Table 2.

Risk of incident dementia in relation to 5 units higher body mass index measured at different age categories in the Swedish Twin Registry

Age category	20–34	35–49	50–64	65–79	80+
N	8098	10,424	11,941	13,224	2565
Main modela	1.10 (0.98–1.23)	1.15 (1.07–1.24)	1.11 (1.01–1.22)	0.96 (0.90–1.01)	0.90 (0.81–1.00)
Main model, genotypeda	1.18 (0.96–1.44)	1.12 (0.98–1.26)	0.99 (0.87–1.12)	0.94 (0.85–1.03)	0.87 (0.75–1.01)
Adjusted for
PGSBMIb	1.20 (0.98–1.47)	1.12 (0.99–1.28)	0.98 (0.86–1.12)	0.93 (0.84–1.02)	0.88 (0.75–1.03)
PGSBMI and PGSADc	1.14 (0.94–1.40)	1.13 (0.99–1.29)	0.98 (0.86–1.13)	0.94 (0.85–1.04)	0.88 (0.75–1.03)
By tertiles of PGSBMId
Lowest tertile	1.28 (0.91–1.80)	1.38 (1.08–1.78)	1.11 (0.87–1.42)	0.91 (0.76–1.09)	1.13 (0.86–1.47)
Middle tertile	1.20 (0.85–1.70)	1.12 (0.89–1.40)	0.91 (0.72–1.16)	0.87 (0.73–1.03)	0.79 (0.60–1.04)
Highest tertile	1.11 (0.79–1.56)	0.98 (0.79–1.20)	0.96 (0.78–1.19)	0.97 (0.84–1.13)	0.70 (0.52–0.94)
p value interaction	0.55	0.04	0.44	0.50	0.01
Co-twin control modela
All twins	1.06 (0.75–1.48)	1.21 (0.97–1.50)	1.18 (0.94–1.49)	0.90 (0.77–1.05)	1.16 (0.82–1.64)
Dizygotic twins	1.06 (0.73–1.54)	1.25 (0.98–1.60)	1.24 (0.96–1.61)	0.93 (0.79–1.10)	1.15 (0.78–1.69)
Monozygotic twins	1.03 (0.47–2.27)	1.07 (0.68–1.68)	0.98 (0.59–1.63)	0.76 (0.50–1.15)	1.19 (0.53–2.65)

Hazard rate ratios (95% confidence intervals) of dementia in relation to 5 units higher body mass index measured at different age categories in the Swedish Twin Registry sample. All models are adjusted for age, sex, smoking, and education

PGS polygenic score, BMI body mass index, AD Alzheimer’s disease

^aDementia = BMI + age + sex + smoking + education

^bDementia = BMI + age + sex + smoking + education + PGS_BMI

^cDementia = BMI + age + sex + smoking + education + PGS_BMI + PGS_AD

^dDementia = BMI + age + sex + smoking + education + PGS_BMI + BMI*PGS_BMI