Serum Folate and B12 Levels in Association With Cognitive Impairment Among Seniors

Abstract

Low folate levels are associated with cognitive impairment of seniors; underlying pathophysiological mechanisms should be further explored.

Folate and B12 serum levels in association with depression in the aged: a systematic review and meta-analysis

“…Additionally, the score in one of these studies (Penninx et al, 2000) was further reduced to 5/8, given that the sample comprised of physically disabled women, thus threatening representativeness and potentially causing a risk of selection bias. By contrast, five studies (Kim et al, 2008;Michelakos et al, 2013;Ng et al, 2009;Ramos et al, 2004;Tiemeier et al, 2002;) scored a perfect 8/8. Lastly, one-included cohort study (Kim et al, 2008) was evaluated as a cross-sectional study, given that only the baseline data were included in the meta-analysis.…”

“…Lastly, it has recently been suggested that the L-methylfolate formation of folate may be more bioavailable as it enters the one carbon cycle after the step where MTHFR is needed; therefore, it should be administered instead of folic acid, especially in patients with this genetic variation as well as in those taking specific other medication or consuming alcohol. Interestingly, a previous meta-analysis from our group on the role of potential supplementation of the older age people also highlighted the sizeable role of low folate levels in affecting late-life cognitive function (Michelakos et al, 2013).…”

“…The current meta-analysis, includes two more studies (Kivela et al, 1989;Ortega et al, 1996) which were not identified in the 2007 meta-analysis, as well as the results of four more recent sizeable investigations (Hin et al, 2006;Kim et al, 2008;Ng et al, 2009;Pan et al, 2012) and examines, to the extent possible, the role of these B-complex vitamins exclusively in the group of the older age people and by gender. As countertrends by gender appeared in each one of the constituent studies availing gender-specific estimates (Lindeman et al, 2000;Penninx et al, 2000;Ramos et al, 2004), as well as the reanalyzed Greek data (Michelakos et al, 2013), we intensively contacted the authors of studies presenting combined-gender results and requested the recalculation of gender-specific estimates in order to come up with more robust data, but without success.…”

“…Corresponding authors were subsequently contacted for missing data, such as adjusted odds ratios (ORs) and sub-analyses by gender in studies providing only overall results with a minimal response rate as only one corresponding author provided raw data regarding his publication (Lindeman et al, 2000). Several of the authors of this study had previously contributed to a meta-analysis including unpublished Greek data on the role of folate and B12 in cognitive impairment (Michelakos et al, 2013). We rerun the analysis of these Greek data with focus on late-life depression and we included the results in this meta-analysis.…”

“…One study on overlapping populations was excluded (Tiemeier et al, 2006), whereas results from five studies could not be included due to the missing data and no response from the corresponding authors following repeated email contacts (Bjelland, Tell, Vollset, Refsum, & Ueland, 2003;Muangpaisan, Petcharat, & Srinonprasert, 2012;Robinson et al, 2011;Skarupski et al, 2010;Vogiatzoglou et al, 2013). By the end of the data collection period, 11 studies were included in this meta-analysis availing serum folate levels among 7949 individuals, 9 of which also serum B12 levels among 6308 individuals (Hin et al, 2006;Kim et al, 2008;Kivela, Pahkala, & Eronen, 1989;Lindeman et al, 2000;Michelakos et al, 2013;Ng, Feng, Niti, Kua, & Yap, 2009;Ortega et al, 1996;Pan et al, 2012;Penninx et al, 2000;Ramos,et al, 2004;Tiemeier et al, 2002). To further explore gender-specific relationships, data were eventually availed for four studies pertaining to the metaanalysis on folate levels (2189 females and 1220 males) and three to the B12 one (1330 females and 604 males) ( Figure 1).…”