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Have you ever opened the fridge, only to forget what you wanted out of it? Have you forgotten a good friend’s name when doing introductions? Do you frequently misplace your car keys or glasses? Do you sometimes pause during a sentence because you can’t quite name the word you are thinking about? Are you worried that you are losing your mind?

Although these can all be very early symptoms of dementia, they may also just be age-related changes in the brain that cause some decline in short-term memory and slowing in your learning ability. 1 Dementia on the other hand is a slow, progressive decline in mental function that includes memory, thinking, judgement and the ability to learn that will eventually lead to an inability to perform normal daily tasks, like driving, cooking and handling finances. 1

There is no certain way to prevent all types of dementia as some of the risk factors such as ageing and family history are difficult or impossible to change. 2 However, research has shown that by modifying the risk factors we are able to change, we can reduce our risk of dementia by 30%. 2 Did you know that some of these risk factors (high blood pressure, diabetes and high cholesterol) are also risk factors for heart attacks and strokes? So, experts agree that what’s good for your heart is also good for your brain. 2

Ways to help keep your mind healthy: 2

  • Eat a healthy, balanced diet – a diet high in saturated fats, salt and sugar can increase your risk of high blood pressure, high cholesterol, becoming overweight or obese, and type 2 diabetes
  • Maintain a healthy weight – overweight or obesity increases blood pressure and risk of type 2 diabetes
  • Exercise regularly – helps to prevent high blood pressure, overweight and obesity and type 2 diabetes
  • Keep alcohol to a minimum – excessive alcohol can damage your brain
  • Stop smoking – smoking can damage your arteries and cause them to narrow, which can increase your blood pressure
  • Treat depression – untreated depression increases your risk of developing dementia
  • If you have chronic conditions such as high blood pressure, diabetes or high cholesterol, make sure that you are getting the right treatment and keeping them under control 2,3
  • Maintain a healthy gut-brain axis by promoting the growth of healthy bacteria in your gut 4,5

Probiotics and the gut-brain axis

visual: relationship between the gut and brain

Research has shown that the gut and brain are connected – a partnership called the gut-brain axis. 6 The gut and brain communicate backwards and forwards through the vagus nerve (the longest nerve in the body) and through hormones and neurotransmitters (chemicals that help transmit signals from one nerve to another). 6,7 The gut has been referred to as the “second brain” as it produces many of the same neurotransmitters as the brain. 7 In fact, it is estimated that 90 % of serotonin (a neurotransmitter that helps to regulate mood) is made in the digestive tract. 7 So how do probiotics fit into the gut-brain axis? Studies have shown that probiotics may help boost mood and mental function and lower stress and anxiety. 7 For example, a study in patients with Alzheimer’s Disease (a form of dementia) showed that probiotics improved mental function. 4

The brain sends signals to the gut to control gut motility, secretions and immune functions. 5 When your brain senses trouble – the flight or fright response – it sends warning signals to your gut, which can explain why stressful situations may give you an upset tummy. 7

The gut influences the brain through its microbiota (healthy bacteria that live in the gut). Although the mechanisms through which these microbiota affect brain function are poorly understood, 8 they are thought to:

  • Have a role in regulating the transport of nutrients into the brain and waste products out of the brain 6
  • Have a role in preventing the entry of harmful substances into the brain 6
  • Produce neurotransmitters such as serotonin and dopamine that are involved in mood regulation 6
  • Have a direct effect on the immune system 6
  • Influence the inflammatory reactions within the brain 5
  • Play a key role in maintaining brain health 5
  • Play a role in modulating stress, depression and anxiety 5
  • Directly modulate the nervous system of the gut 8
  • Help regulate appetite by telling the brain when it’s time to stop eating 7,8

High Blood Pressure

man being tested for high blood pressure

Studies have shown that high blood pressure in your mid-life years increases your risk of a decline in mental function decline and dementia. 9,10

Mechanisms include:

  • Untreated high blood pressure can cause lesions in the brain tissue, which can interfere with nerve pathways 10
  • Fatty plaques may build up in small arteries and can decrease blood flow to brain 10
  • Rupture of these plaques or pieces that break off (emboli) can block blood supply to brain causing “mini” strokes 10
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Diabetes

diabetes spelled out with digital testing machine

If you have diabetes or insulin resistance you may be at risk for a decline in mental function and dementia. 11

Mechanisms are not fully understood but may include: 11

  • Degeneration of brain cells 11
  • Damage to arteries supplying the brain, leading to decreased blood supply 11
  • Insulin resistance or low insulin levels may affect the way the brain uses glucose (sugar) and this could affect nerve pathways 11
  • Chronic exposure to high glucose levels can lead to the formation of products that promote cell ageing and the formation of brain plaques (lesions) 11
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High cholesterol

cholesterol dial indicating high

Abnormal lipid levels (high cholesterol, HDL-cholesterol, and triglycerides and low HDL-cholesterol) in your midlife years can increase your risk for dementia. 12

Mechanisms are not fully understood but may include: 12

  • Fatty plaques may build up in small arteries and can decrease blood flow to brain 3
  • High cholesterol also leads to an increase in plaques (lesions) in the brain 3
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References: 1. Huang J. Dementia. MSD Manual Consumer Version. [online] 2018 Mar [cited 2018 Oct 3]. Available from: URL: https://www.msdmanuals.com/home/brain,-spinal-cord,-and-nerve-disorders/delirium-and-dementia/dementia. 2. Dementia guide: Can dementia be prevented? [online] 2018 Mar [cited 2018 Oct 3]. Available from: URL: ps://www.nhs.uk/conditions/dementia/dementia-prevention/. 3. Takeda JRT, Matos TM, de Souza-Talarico JN. Cardiovascular risk factors and cognitive performance in aging. Dement Neuropsychol 2017;11(4):442-448. 4. Akbari E, Aemi Z, Kakhaki RD, Bahmani F, Kouchaki E, Tamtaji OR, et al. Effect of Probiotic Supplementation on Cognitive Function and Metabolic Status in Alzheimer’s Disease: A Randomized, Double-Blind and Controlled Trial. Frontiers Aging Neurosci 2016;8:Article 256. 5. Mohajeri MH, La Fata G, Stienert RE, Weber P. Relationship between the gut microbiome and brain function. Nutr Rev 2018;76(7):481-496. 6. Cerdó T, Ruíz A, Suárez A, Campoy C. Probiotic, Prebiotic, and Brain Development. Nutr 2017;9(1247):doi:10.3390. 7. Harvard Medical School Guide. The Benefits of Probiotics: Using good bacteria for better health. [online] [cited 2018 Nov 12]. Available from: URL: http://www.health.harvard.edu. 8. Sarkar A, Lehto SM, Harty S, Dinan TG, Cryan JF, Burnet PWJ. Psychobiotics and the Manipulation of Bacteria-Gut-Brain Signals. Trends Neurosci 2016;39(11):763-778. 9. Igase M, Kohara K, Miki T. The Association between Hypertension and Dementia in the Elderly. Int J Hypertens 2012;2012: Article ID 320648. 10. Kennelly SP, Lawlor BA, Kenny RA. Blood pressure and dementia – a comprehensive review. The Adv Neur Disord 2009;2(4):241-260. 11. Ravona-Springer R, Schaider-Beeri M. The association of diabetes and dementia and possible implications for nondiabetic populations. Exp Rev Neurother 2011;11(11):1609-1617. 12. Li R, Wang T-J, Lyu P-Y, Liu Y, Chen W-H, Fan M-Y, et al. Effects of Plasma Lipids and Statins on Cognitive Function. Chinese Med J 2018;131(4):471-476.

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