OBJECTIVES

Bipolar disorder (BD) has been associated with an elevated risk of Alzheimer's Disease (AD). We assessed AD biomarkers in BD and tested whether epigenetic aging (EA) acceleration is a potential mechanism driving variability in these markers.

DESIGN SETTING PARTICIPANTS

Cross-sectional study of n=59 living individuals with BD and n=20 age- and sex-equated control participants, as well as analyses of postmortem brain samples (Brodmann area 9/46) from n=46 individuals with BD.

MEASUREMENTS

Amyloid beta (Aβ), Aβ, and total Tau levels were measured in plasma from individuals with BD and controls, and Aβ levels were measured in brains. EA and its acceleration (blood: GrimAge and DunedinPACE; brains: DNAmClock) were estimated for all samples. Individuals with BD were split into quartiles with accelerated or slower EA if they were in the first or fourth quartiles for GrimAge acceleration (AgeAccelGrim), DunedinPACE, or DNAmClock acceleration (DNAmClockAccel).

RESULTS

Individuals with BD showed an increase in Aβ (p=.049) and a decrease in the Aβ ratio (p=.035) compared to controls. A decrease in the Aβ ratio was also found in individuals with BD with high versus low AgeAccelGrim (p=.028). Brain Aβ levels significantly correlated with DNAmClockAccel (r=.270, p=.007), with those with high EA acceleration showing higher brain Aβ after controlling for confounders (p=.008).

CONCLUSIONS

Our results provide preliminary evidence that EA may explain the variability in AD risk in individuals with BD and could act as a target for preventing dementia and AD in BD.