Processed Meats Increase Risk of Dementia

A recent study published in Neurology on 11 February 2025, led by researchers from Brigham and Women’s Hospital, has investigated the relationship between long-term red meat consumption and the risk of dementia and cognitive decline in U.S. adults. The study utilised data from the Nurses’ Health Study and the Health Professionals Follow-Up Study, encompassing approximately 170,000 participants over a 43-year period. 

Key Findings:

• Processed Red Meat and Dementia Risk: Individuals with the highest intake of processed red meats—such as bacon, sausages, and hot dogs—exhibited a 13% higher risk of developing dementia compared to those with lower consumption levels.
• Cognitive Decline: High consumption of processed red meats was associated with a 14% increase in subjective cognitive decline, indicating a perceived worsening of cognitive abilities over time.
• Unprocessed Red Meat: The study found that unprocessed red meats, such as beef, lamb, and pork, also contributed to cognitive risks, potentially due to harmful substances like nitrates, sodium, and saturated fats present in these meats.

Mechanisms Behind the Findings:

The detrimental effects of processed red meats on cognitive health are believed to be linked to several factors:

• Nitrates and Nitrites: Commonly used as preservatives in processed meats, these compounds can form nitrosamines, which have been implicated in neurodegenerative processes.
• High Sodium Content: Elevated sodium levels can lead to hypertension, a known risk factor for vascular dementia.
• Saturated Fats: High levels of saturated fats in processed meats are associated with cardiovascular diseases, which can indirectly affect brain health.

Dietary Recommendations:

Based on the findings, the researchers suggest several dietary modifications to mitigate dementia risk:

• Reduce Processed Red Meat Intake: Limiting the consumption of processed meats can lower the risk of cognitive decline.
• Substitute with Healthier Protein Sources: Replacing processed red meats with alternatives such as fish, poultry, nuts, and legumes has been associated with a reduced risk of dementia. For instance, substituting processed red meat with fish was linked to a 28% reduction in dementia risk.
• Adopt Brain-Healthy Diets: Diets like the Mediterranean, DASH, and MIND diets, which are low in red meat and rich in fruits, vegetables, whole grains, and healthy fats, have been associated with decreased dementia risks.

Conclusion:

This extensive study underscores the importance of dietary choices in maintaining cognitive health. Limiting the intake of processed red meats and opting for healthier protein sources may significantly reduce the risk of dementia and support long-term cognitive function.

Vitamin D and Alzheimer’s Disease

Unfortunately there is currently an absence of curative and preventative interventions for Alzheimer’s Disease (AD). Last year, Panza et al. reviewed the research on the links between vitamin D and AD. Low vitamin D levels have been associated with an accelerated decline in cognitive functions. They have also been associated with the development of chronic brain conditions such as AD and other dementias. As such, vitamin D is often thought of as a neurosteroid due to its effect on brain conditions. The authors believe more research is required to determine the effect of vitamin D supplementation on the prevention and/or treatment of AD.

Chronic Pain Linked to Memory Decline and Dementia

A study by Whitlock et al from the University of California, published in this month’s Jama Internal Medicine, looked into the relationship between persistent pain, memory decline and dementia. Over 10,000 senior citizens (median age of 73 years) from the Health and Retirement Study were followed for 12 years.

At baseline, persistent pain affected 11% of participants and was linked with more restrictions in daily activities and more symptoms of depression. Those with persistent pain had a greater risk (9%) of having a more rapid memory decline than those without pain. They also had a smaller increase in risk (2%) of developing dementia. These changes significantly increased the chances of being unable to manage medications (16%) or finances (12%).

What’s the causal connection between chronic pain, memory decline and dementia? The authors believe the severity of pain can decrease attention capacity and impair memory consolidation. Additionally, pain leads to stress, and stress has been shown to promote cognitive decline, mainly through hypotrophy of the hippocampus. In my opinion, the disruption of sleep can also contribute to poor memory and a decline in cognitive ability because, as we know, sleep is involved in memory processing and consolidation.

Fortunately, physiotherapy, rehabilitation, relaxation and mindfulness meditation are effective at addressing chronic pain.

Resistance Training Improves Mental Function

Mild cognitive impairment (MCI) is a condition where a person has minor problems with things like memory, thinking, attention, language or visual depth perception. The problems are usually not severe enough to affect activities of daily living. But some people with MCI go on to develop dementia – Alzheimer’s in particular. A new study published in the Journal of the American Geriatrics Society by Mavros et al from the University of Sydney has looked into the effects of strength training on cognitive function. The researchers selected 100 people with MCI aged 55 or over. Part of the subjects were put through progressive resistance training (PRT) 2x/week for 6 months. Unsurprisingly, the resistance training led to increases in strength but interestingly the strength increases were linked to improvements in mental ability. The researchers conclude that the link between strength gains and cognitive function merits further study.