Preventive Neurology

I had a terrible night last night. One of my patients who has been under my care for over a decade was admitted to a district hospital with life-threatening sepsis and has to have emergency surgery. It is touch and go if this patient will survive. I kept tossing and turning and rehearsing events that led up to their admission and kept wondering if anything could have been done to prevent the sepsis from progressing to a stage when it required surgery. The result is I had a very poor night’s sleep and feel terrible this morning; irritable, tired, groggy and foggy as if I have a hangover. What damage has this caused? Photo by engin akyurt on Unsplash It is clear that sleep is a physiological must; acute sleep deprivation is a major life-threatening stressor and kills. This is why it is used as a method of torture. Chronic sleep deprivation is also a stressor and also kills, only more slowly. The paper by Eide and colleagues below shows how one night’s sleep deprivation impairs the brain...

Photo by Mark Paton on Unsplash We know that exercise is important for brain health has the potential to delay, or prevent, all cause-dementia in the general population. Hearing loss has recently also been identified as an important and potentially modifiable risk factor for dementia. Are hearing loss and physical activity related to each other? This study below shows in elderly people that hearing loss is associated with a worse physical activity profile. Is this association or causation? Is hearing loss part of the dementia prodrome and hence is associated with other prodromal features of dementia such as poor motivation, social isolation, lower mood, etc., which lead to less activity? Or is less activity in old age related to a lifetime of less activity and hence a higher risk of dementia and is simply associated with loss of hearing? Does hearing loss impact one's ability to exercise? Does less environmental auditory feedback make it less likely that you go out and exercise? I...

Photo by i yunmai on Unsplash It looks like we have to rethink what a healthy BMI is!  This study below shows that above a BMI of 23 kg/m2 there is a linear increase in risk of severe COVID-19 leading to admission to hospital and death, and a linear increase in admission to an ICU across the whole BMI range, which is not attributable to excess risks of related diseases. The important thing to point out is that the relative risk due to increasing BMI is particularly notable in people younger than 40 years and of black ethnicity . This means that if your BMI (weight/height (m)-squared) is above 23 you should probably do something about it. In parallel to this, I read an article a few weeks ago that said you need to get back to what you weighed when you were aged 21. If I did this I would need to lose 13kg (2 stones) and my BMI would be 22. So I am going to get on the case and will be joining the #BackTo21 challenge and in so doing maximising my chances of doing okay if I ever get...

Photo by sk on Unsplash The stress response is hardwired into the primate genome. Clearly, the acute stress response is critical for the survival of the fittest. In comparison, a chronic stress response comes at a price. Some people like to think of stress as some subjective phenomenon that you measure on a Lickert scale from 0 (no stress) to 7 (severe or intolerable stress). However, the stress response is biological with glucocorticoid production being the biomarker of choice for measuring stress; i.e. the area-under-the-cortisol-curve over time is how we measure chronic stress. In the field study below of female baboons, chronic glucocorticoid exposure predicted life expectancy. A hypothetical female who maintained glucocorticoid levels in the top decile for her age across adulthood would be expected to lose 5.4 years of life relative to a female who maintained glucocorticoid in the bottom decile for her age. With the life expectancy of the average baboon being 35-45 years of age ...

Photo by engin akyurt on Unsplash "I was told to try the Snack-All-Day diet plan, but it has been a disaster. I was eating 7 or 8 small snacks per day but instead of losing weight, I have gained weight. Why?"   It is quite clear that obesity is a major public health problem and contributes to a substantial burden of disease at a population level. Why do we get obese? This is complex, but a lot of it can be explained by the food environment we live in and the change in our eating habits over the last 3 or 4 generations. The study below shows that the extent of the postprandial dip in glucose, which occurs 2-3 hours after a meal predicts hunger, a shorter time until the next meal and greater additional energy intake at 3-4 hours.  The reason why we get low blood glucose 2-3 hours after a meal is that there is too much insulin released relative to the amount of sugar or glucose in the baseline meal. In other words, our bodies produce too much insulin in anticipation of the...

The role sleep plays in normal human brain physiology is becoming more clear as the link between abnormal sleep and dementia gets stronger. Here is yet another epidemiological study linking reduced sleep in middle age to a higher risk of dementia. Quin Stevenson on Unsplash Is the association between reduced sleep and dementia causal or is it due to reverse causation? Sleep is required to consolidate memories and to allow the brain to cleanse itself, i.e. flush out all the intracellular debris that could aggregate to cause Alzheimer’s disease. Therefore, sleep deprivation by impairing memory consolidation and not allowing you to clear the brain's intracellular debris properly could lower your threshold for developing dementia in the future. Reverse causation states that people who are destined to develop dementia have pathology that starts decades before dementia manifests, for example, amyloid deposition and neurofibrillary tangles. The pathology affects parts of the brain that c...

Kinga Cichewicz on Unsplash The study below found that people who experience unconscious wakefulness most often and for longer periods of time had nearly double the risk of dying from cardiovascular disease during an average of between 6 and 11 years’ follow-up when compared to the risk in the general population. The association was particularly strong in women and less clear in men. Unconscious wakefulness also referred to as cortical arousal, is a normal part of sleep. It occurs spontaneously and is part of the body’s ability to respond to potentially dangerous situations, such as noise or breathing becoming obstructed. A full bladder, pain, limb movements, trauma, temperature, light, noise, sleep disorders, acid reflux, depression and anxiety can also be triggers. Clearly, unconscious wakefulness is a major modifiable risk factor for cardiovascular disease and is also a risk factor for all-cause dementia. Isn’t it about time we took this seriously and started a public health campai...