A dietary defense against cognitive decline

In a recent study published in the journal Dr nutrients, Researchers investigated the relationship between dietary mineral consumption and cognitive impairment (CI) risk in elderly Spanish individuals. CI was classified using the Montreal Cognitive Assessment (MoCA) test, a highly sensitive and specific but rarely used method. The results of the study showed that 54.2% of the 201 participants presented CI (MoCA <26). Increased iron and manganese intake in women and reduced CI risk in women. However, no association between mineral intake and CI could be established in men.

Study: Relationship between mineral intake and cognition assessed by the Montreal Cognitive Assessment (MOCA): a cross-sectional study.. Image credit: Created with assistance from DALL·E 3

Can we use diet to fight neurodegeneration?

Modern medicine has extended human life expectancy, increasing the incidence of age-related chronic conditions including cancer, cardiovascular disorders, and neurodegenerative diseases. Dementia, a group of neurological conditions characterized by memory loss and other severe thought disorders, is one of the most common diseases among older adults. It is estimated to affect 50 million individuals worldwide, with an additional 10 million patients annually.

The role of MCI in dementia

Dementia pathology often begins as mild cognitive impairment (MCI), which is characterized by subjective expert observation and objective comparison with the patient’s previous functioning. Although MCI can be delayed by behavioral and lifestyle changes (diet, hypertension therapy, cognitive stimulation), no pharmacologically approved ‘cure’ exists for the condition. MCI patients over the age of 65 have a 5-fold increased risk of developing dementia (especially Alzheimer’s disease). [AD]) compared to adults without MCI.

Lifestyle interventions: A glimmer of hope

Studies have shown that more than 50% of patients with MCI progress to dementia within five years of developing MCI, experts consider MCI a critical stage for modifiable lifestyle interventions, which can delay or reverse MCI before the onset of AD. Physical activity, smoking/alcohol consumption cessation, and dietary interventions are the best studied of these interventions.

Neurological benefits of food

Dietary patterns have been identified with beneficial neurological associations, including the Mediterranean diet, Dietary Approaches to Stop Hypertension (DASH), and the Mediterranean-DASH Diet Intervention for Neurodegenerative Delay (MIND). Research on the link between neurology and diet has focused on biomolecules and clinical outcomes with limited evidence for the mechanistic effects of individual dietary components such as vitamins, minerals and fatty acids.

Minerals including iron, copper, zinc, magnesium, manganese and selenium have been suggested to be linked to cognitive function due to their role in DNA repair and their antioxidant properties. However, this hypothesis has not been formally tested within a structured scientific framework.

Study design and methods

In the current study, researchers examined the relationship between dietary mineral intake and cognitive impairment. Participants for the study were recruited from the “Cognitive and Neurophysiological Characteristics of Individuals at High Risk for Developing Dementia: A Multidimensional Approach” (COGDEM) cohort. The cross-sectional study initially included 262 Spanish individuals, of whom 201 met the inclusion criteria. Inclusion criteria included a baseline Mini-Mental State Examination (MMSE) score ≥ 24 and a Geriatric Depression Scale (GDS) short-form score ≤ 5.

Data collection and evaluation

Data collected from the study cohort included health and socio-demographic data, three-day food intake records (diet), anthropometric data, physical activity measurements, genotyping and neuropsychological assessments.

Health and socio-demographic data were collected through a questionnaire that recorded employment status, education level, and chronic medical conditions (especially depression, hypertension, and diabetes). Food record data were collected using Dial Nutritional Analysis software. Nutrients of interest included energy (kcal/day), magnesium (mg/day), iron (mg/day), copper (µg/day), selenium (µg/day), manganese (mg/day), and zinc (mg /day). Minerals were standardized for caloric intake using the Willett residual model. Dietary Reference Intakes (DRIs) were used to calculate relative mineral contributions.

Anthropometric data collected consisted of weight, height and body mass index (BMI) according to The International Society for the Advancement of Kinanthropometry (ISAK) guidelines. Physical activity data were collected using a right-hip-attached accelerometer over seven days.

Genotyping was performed to identify and investigate apolipoprotein E (APOE) alleles in participants (eg, rs7412 and rs429358 polymorphisms). Based on genotyping results, individuals were classified as carriers (APOE ε4+) or non-carriers (APOE ε4−) of the ε4 allele. This allele is strongly associated with AD.

Neuropsychological testing included the GDS test for depression, the MMSE and the Montreal Cognitive Assessment (MoCA) to assess immediate memory, attention, calculation ability, and language.

“MoCA is a cognitive screening tool to aid in the detection of mild cognitive impairment (MCI). [37]. This test has been validated for the Spanish population. “This test studies various abilities such as attention, concentration, memory, language and executive functioning.”

The MoCA is a 30-point test with scores <26 indicating MCI. As this study did not include any clinical assessment of MCI, MoCA <26 was taken as the criterion for MCI classification.

Key research findings

Of the 201 participants included in the study, 63.2% were female, with a mean age of 59.8 years. MoCA assessment identified 54.3% of participants as having MCI (34.3% female and 19.9% ​​male). Education status was the only non-dietary variable observed to play a role in CI – the higher the education status, the lower the likelihood of MCI. Other anthropometric, exercise, and genotyping results did not depict statistically significant associations with CI risk.

The most significant dietary associations were contributions to the daily recommended intake (DRI) of iron and manganese in women – higher intakes of these minerals were associated with lower CI prevalence. Copper DRI contributions in women were also positively correlated with beneficial CI outcomes, although this interaction was not as significant as for iron and manganese.

Gender-specific results

Surprisingly, no association was established between any dietary mineral and positive CI outcomes in male participants.

Concluding remarks and future directions

The present study investigated the association between common dietary minerals and cognitive impairment as measured by the MoCA test. The results highlight the importance of high iron and manganese intake, particularly in women. These minerals, and to a lesser extent, copper, provide a protective effect against MCI progression and AD onset. No association was found between mineral intake and cognition in men.

“Intervention and follow-up studies monitoring dietary intake and nutritional status (including biochemical parameters) are needed to confirm the potential protective effect of iron and manganese intake on cognitive impairment and to look deeper into the differences found in these associations between mineral intake and sex-specific cognitive function. .”