Hooshmand B, et al. - Via performing a cohort study of longitudinal data from 2,570 elderly adults (dementia-free at baseline; aged 60-102 years), researchers examined the correlation of serum markers of methylation status and sulfur amino acids with risk of incident dementia, Alzheimer disease (AD), and the rate of total brain tissue volume loss. During the 6-year study duration, the methionine to homocysteine status was concluded to be related to dementia development and structural brain changes, which implied that a higher methionine to homocysteine ratio may be significant in decreasing the rate of brain atrophy and decreasing the risk of dementia among the elderly.

Methods

• This population-based study was performed from March 21, 2001, to October 10, 2010, in a sample from the Swedish Study on Aging and Care in Kungsholmen, in which participants had undergone comprehensive examinations and structural brain MRI on 2-3 occasions over 6 years.
• From March 1, 2018, to October 1, 2018, data evaluation was completed.

Results

• In individuals who took vitamin supplements, the methionine to homocysteine ratio was higher (median: 1.9; IQR: 1.5–2.6) in comparison with those who did not (median: 1.8; IQR: 1.3–2.3; P < 0.001), and rose per each quartile increase of vitamin B12 or folate.
• In the multi-adjusted model, an increased baseline serum total homocysteine level was correlated with an elevated risk of dementia and AD (ie, for the highest homocysteine quartile vs the lowest, the HRs were 1.60 and 2.33 for dementia and for AD, respectively), during the 6-year study period.
• On the other hand, higher levels of methionine were associated with a reduced dementia risk.
• Greater values of the methionine to homocysteine ratio were significantly correlated with lower risk of dementia and AD (ie, for the fourth methionine-homocysteine quartile compared with the first quartile, the HR was 0.44 and 0.43, respectively, for incident dementia and for AD).
• A higher methionine to homocysteine ratio was related to a reduced rate of total brain tissue volume loss during the study period, in the multi-adjusted linear mixed models (β [SE] per 1-SD increase: 0.038 [0.014]; P = 0.007).