Memory complaints as a precursor of memory impairment in older people

The main finding of this study is that, irrespective of all measured
potential confounders, increased dietary vitamin K intake
was associated with fewer and less severe SMC among older adults
taking no VKA. Specifically, patients with serious SMC consumed
96 g (24.3%) less vitamin K each day.
These findings are consistent with the emerging epidemiological
literature on vitamin K and cognition. Using standard objective
neuropsychological testing, previous studies have reported associations
of decreased serumphylloquinone concentration with worse
episodic memory performance in older adults [5] and with AD [6].
Associations between lower dietary vitamin K intake and AD have
also been reported [10,11]. Conversely,the link between the dietary
vitamin K intake and the subjective perception of cognitive decline
has never been studied. Thus, the present paper provides additional
information, notably the first evidence, to the best of our
knowledge, of an association between vitamin K and SMC. SMC
is one of the most frequently encountered complaints in seniors,
with prevalence around 50% [21]. Importantly, although SMC has
limited association with objective cognitive performance, it is predictive
of unfavourable cognitive outcomes such as an increased
risk of converting to Mild Cognitive Impairment(MCI) or to dementia
[21]. Moreover, SMC is well-known to cause anxiety and to
affect patients’ quality of life [22]. Thus, finding that dietary vitamin
K intake is associated with more frequent and more severe
SMC has potential clinical implications for the understanding and
management of SMC and related adverse effects.
How dietary vitamin K intake is associated with SMC is not completely
understood. Vitamin K exerts action in the brain, mostly as
menaquinone-4 (i.e., vitamin K2) [2–4]. Vitamin K modulates the
synthesis and metabolism of sphingolipids, which are major constituents
of the myelin sheath and neuronal membranes, and also
key players in neuronal proliferation, differentiation, senesce