The newly published data, from researchers at Shanghai Sixth People's Hospital and Shanghai Jiao Tong University School of Medicine, in China, suggest daily B vitamins, folic acid and CoQ10 supplementation could prevent the occurrence of cognitive impairment. They add that occasional vitamin D (VD) supplementation may reduce the risk of Alzheimer's Disease (AD) and occasional B vitamin supplements may also reduce the risk of cognitive impairment.
The effects of multivitamins on cognitive decline and dementia have been widely studied. A previous publication identified three-level prevention of AD based on the theory of ‘intestinal flora-brain-intestine axis’ and emphasised the importance of 'early, coordinated, holistic and long-term’ nutrition intervention.
Supplementing various vitamins in the diet is considered a means to maintain cognitive function.
On the importance of progressing research, the new study authors said: “During the prodromal period of AD, we look forward to early identification of various protective and risk factors of AD and appropriate implementation of non-drug intervention strategies such as behavioural prevention strategies to provide a basis for delaying the progression of dementia.”
They conclude: “We provide evidence-based recommendations that daily supplementation of VD, folic acid, B vitamins and CoQ10 may be a potential preventive measure to slow cognitive decline and neurodegeneration in the elderly.”
The most frequent type of dementia is AD. The initial stage is characterised by short-term memory loss, followed by gradual impairment in numerous cognitive areas. As life expectancy rises, so does the prevalence of neurological illnesses associated with ageing.
Recent epidemiological surveys in China and the United States, however, suggest that the adjusted prevalence rate of moderate cognitive impairment (MCI) is more than double that of AD.
In China, the total prevalence of dementia in adults aged 60 and over is 6%, and it is estimated that there are around 15.07 million people with dementia, with AD accounting for approximately 9.83 million (65.23%).
Despite the in-depth investigation of pathological indicators of cognitive decline in recent years, the clinical diagnosis of AD remains reliant on clinical phenotypic presentations.
Subjective cognitive decline (SCD), one of the earliest noticeable symptoms of Alzheimer's disease and related dementias, can proceed to MCI, which can be detected via neuropsychological tests. MCI is the earliest stage at which AD can be diagnosed, followed by steady deterioration of cognitive and functional impairments, resulting in loss of independence and death.
People over the age of 50 were recruited from the Shanghai Sixth People’s Hospital for this population-based cross-sectional study, and were divided into a normal control (NC) group, a SCD group, an MCI group and an AD group.
The study used dietary habit questionnaires to collect information from patients, including: basic clinical information, demographic data, basic physical condition, disease history, pharmacological history, and personal history, including smoking and drinking habits, and vitamin supplement usage (folic acid, B vitamins, VD, CoQ10).
The dietary habit questionnaire was completed by family members or others familiar with the subjects' eating habits, therefore the questionnaire's reliability was unaffected by the patients' cognitive impairment. Medical history inquiry, physical examination, neuropsychological test, and laboratory examinations also featured in the assessment.
Analysis of the data found that adequate intake of folic acid, vitamin B6 and vitamin B12 was significantly associated with better cognitive reserve and reduced oxidative damage.
The results also indicated a lower risk of AD in the daily VD-supplemented subjects with MCI, compared to those who were not supplemented; a lower risk of cognitive impairment in those with normal cognitive who consumed VD, folic acid or CoQ10 on a daily basis compared those who did not; and a lower risk of cognitive impairment in subjects with normal cognitive performance who consumed B vitamin supplements, either daily or occasionally, compared to those who did not.
Findings confirmed a lower prevalence of cognitive impairment in those who took the vitamins folic acid, B vitamins, VD, and CoQ10 daily. The authors conclude: “We would recommend daily supplementation of vitamins (folic acid, B vitamins, VD, CoQ10) as a potential preventive measure to slow cognitive decline and neurodegeneration in the elderly.”
Mechanism of action
Discussing possible mechanisms of action behind these findings, the authors note a previous study reporting that appropriate consumption of folic acid, vitamin B6, and vitamin B12 was strongly correlated with superior cognitive reserve, which may be attributable to reduced hypermethylation of redox-related genes and reduced oxidative damage.
A recent dose–response meta-analysis showed that the relative risk of AD increased by 15% for every 5 μmol/L increase in blood homocysteine, with speculation that its mechanism related to the abnormal aggregation of tau protein in hippocampal neurons and the inhibition of methylation reaction.
A randomised controlled trial (RCT) reported that folic acid and vitamin B12 could cooperate to inhibit the expression of inflammatory factors, thus improving cognitive ability.
Recent studies have found that CoQ10 protects endothelial cells by promoting mitochondrial function, thus delaying age-related peripheral vascular senescence. CoQ10 was found to to reduce the expression of Apolipoprotein E (APOE) in the hippocampus by improving the energy deficiency and mitochondrial dysfunction.
The main limitation of the cross-sectional study is that it does not control all confounding factors affecting cognition.
The authors state: “We cannot rule out the potential impact of confounding factors on the results of observation. The estimates provided in this study should not be extended to other populations without additional research and validation. However, these findings still deserve further study to explore the relationship between vitamins and cognition.”
“Study of Diet Habits and Cognitive Function in the Chinese Middle-Aged and Elderly Population: The Association between Folic Acid, B Vitamins, Vitamin D, Coenzyme Q10 Supplementation and Cognitive Ability”
Authors: Xinting Jiang, Yihan Guo, Liang Cui, Lin Huang, Qihao Guo and Gaozhong Huang