Nutrition & Psychology-Issue 2: Is Memory Loss Inevitable? A Biological, Social and Cognitive Perspective

Biologically, research indicates that memory decline occurs as a natural part of the biological aging process, but at different rates depending on the individual.? However, from a social and cognitive perspective it would appear there may be modifiable factors to slow memory decline, such as nutrition, education, socialisation and other lifestyle factors.?

Some researchers have proposed that memory decline is inevitable in old age and part of a gradual, diffusive process. Research has indicated, through observational functional MRIs, that a decline of two hippocampal subregions, known as the subiculum and the dentate gyrus, occur as part of the normal aging process (Small et al., 2002). ? Receptors for NMDA in the hippocampus, a subtype of glutamate involved in long term memory, have been suggested to decline with age in mice, although further research is warranted to determine in human models (Magnusson, 2012). Furthermore BDNF, which consolidates short term memories into long term memories, also declines with age (Erickson et al., 2010; Neil & Carson, 2019). Episodic memory, which is formed in the hippocampus, has been shown to decline with age due to degeneration of related structural and functional brain circuitries (Moskovitch et al., 2016; Shing et al., 2010). These factors combined may impair the formation and consolidation of short term memories into long term memory storage, and some researchers have argued that memory decline could therefore be an inevitable part of aging (Maruszak &Thuret, 2014; Rubin et al., 2014).

Conversely, there is evidence which indicates that memory decline may not be an immutable part of aging.? Homocysteine, a metabolite naturally produced by the body during methylation, has been associated with increased risk of cognitive decline when raised. Raised homocysteine?increases levels of inflammation in the body (Li et al., 2015), has a?detrimental impact on the structural integrity of blood vessels (Ganguly & Alam, 2015), and also?affects gene expression (Barroso et al., 2017). These factors may in turn increase the risk of developing chronic diseases, and a?recent review?has suggested that raised homocysteine levels are associated with an increased risk of?around 100 diseases or undesirable outcomes,?including Alzheimer's disease (Smith & Refsum, 2021). Research has indicated that increasing intake of?folate and B12, as well as omega-3,?can help to reduce levels of homocysteine (Oulhaj et al., 2016). This can be done through increasing green leafy vegetables (folate), chicken and fish (B12), and increasing oily fish (omega-3), as well as through supplementation of these nutrients (particularly if vegetarian / vegan, for B12 and omega-3).?

Memory decline has been observed to be statistically significantly lower in a sample of elderly people (n = 16,638) who were well socialised, whereas elderly subjects who were not socially well integrated experienced memory decline at twice the rate (P<.01). Moreover, protective benefits of socialisation were observed to be greatest in those who had more than 12 years of education (Ertel, Glymour & Berkman, 2008). Research has also suggested that bilingualism may exert some neuroprotective effects against memory decline. Elderly individuals who are bilingual have been demonstrated to exhibit better cognitive function and reserve than counterparts who are monolingual (Grady et al., 2015; Klimova, Valis, & Kuca, 2017).

Further investigation is required into nutritional, environmental and lifestyle factors, which may slow or attenuate memory decline. From the present evidence base, further biological research into reducing hippocampus degeneration, increasing BDNF levels, and the role of homocysteine in neurodegeration appear of merit. Furthermore, from a social and cognitive perspective, further research into socialisation and education factors also seem to be areas worth investigating further.

References

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