Investigating The Association Between Serum DHA Levels And Cognitive Decline in Alzheimer's Disease Patients

Against the backdrop of accelerating global aging, the incidence of Alzheimer's disease (AD) is on the rise year by year, imposing a heavy burden on patients' families and society. Currently, most drugs for treating AD can only alleviate symptoms without effectively halting the progression of the disease, making it crucial to explore new intervention methods. Omega-3 polyunsaturated fatty acids (PUFAs), especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), have become a hot topic in AD research due to their potential neuroprotective effects (Dyall, 2015).

Previous studies have shown that Omega-3 PUFAs possess anti-inflammatory (Simonetto et al., 2019) and anti-amyloidogenic properties (Thomas et al., 2015), drawing attention for their role in preventing cognitive decline. Epidemiological studies have found an inverse relationship between fish intake (rich in EPA and DHA) and AD risk (Albanese et al., 2009; Huang et al., 2005). However, clinical intervention trials on the impact of Omega-3 on the rate of cognitive decline in diagnosed dementia patients have yielded mixed results (Lin et al., 2022; Shinto et al., 2014; Quinn et al., 2010; Freund-Levi et al., 2006).

To further investigate the relationship between Omega-3 PUFAs and cognitive function in AD patients, Che-Sheng Chu and colleagues conducted a prospective cohort study (Chu et al., 2022). The team selected 129 AD patients undergoing treatment with acetylcholinesterase inhibitors (AChEIs) from Chang Gung Memorial Hospital, spanning from May 1, 2016, to April 30, 2019, with a two-year follow-up period.

Throughout the study, detailed analyses were performed on patients' dietary records and blood concentrations of Omega-3 PUFAs. Various assessment methods were employed, including cognitive function tests such as the Mini-Mental State Examination (MMSE) and Clinical Dementia Rating Scale (CDR), along with biochemical blood tests. Statistical methods like chi-square tests, non-parametric tests, binary logistic regression, and multivariate linear regression were used during data processing to identify factors related to cognitive decline.

The findings revealed that AD patients with lower baseline Omega-3 levels had a higher risk of cognitive decline over the two-year follow-up period. Further analysis showed a significant association between lower baseline DHA levels and increased risk of cognitive decline in AD patients, whereas EPA levels did not show a notable connection. Additionally, higher Mini-Nutritional Assessment (MNA) scores and total fat intake were linked to slower rates of cognitive decline in AD patients.

This study is the first to establish a clear link between serum DHA levels and cognitive decline among AD patients receiving AChEI treatment, offering new perspectives for AD interventions. However, limitations exist, such as the reliance on patient-reported dietary records for estimating Omega-3 intake, which may introduce recall bias; the relatively small sample size and short follow-up period limiting the generalizability of the findings; and the lack of consideration for factors like apolipoprotein E (apoE) status and vitamin B impacts on the relationship between PUFA intake and cognitive function.

Future research should involve larger scales and longer follow-up periods while optimizing study designs to further clarify the causal relationship between Omega-3 PUFAs and cognitive function in AD patients, providing stronger evidence for the prevention and treatment of AD.

References:

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