Bio-thermodynamics and aging

I suspect nature is constrained by basic physics/chemistry/thermodynamics in a variety of interesting ways.

For example, chemical reactions (and thus biological processes) proceed more quickly when they are warm than cold–this is pretty much a tautology, since temperature=movement–and thus it seems reasonable to expect certain biological processes to proceed more slowly in colder places/seasons than in warmer ones.

The Greenland Shark, which lives in very cold waters, lives to be about 300-500 years old. It’s no coincidence:

Temperature is a basic and essential property of any physical system, including living systems. Even modest variations in temperature can have profound effects on organisms, and it has long been thought that as metabolism increases at higher temperatures so should rates of ageing. Here, we review the literature on how temperature affects longevity, ageing and life history traits. From poikilotherms to homeotherms, there is a clear trend for lower temperature being associated with longer lifespans both in wild populations and in laboratory conditions. Many life-extending manipulations in rodents, such as caloric restriction, also decrease core body temperature.

This implies, in turn, that people (or animals) who overeat will tend to die younger, not necessarily due to any particular effects of having extra lumps of fat around, but because they burn hotter and thus faster.

Weighing more may trigger certain physiological changes–like menarchy–to begin earlier due to the beneficial presence of fat–you don’t want to menstruate if you don’t have at least a little weight to spare–which may in turn speed up certain other parts of aging, but there could be an additional effect on aging just from the presence of more cells in the body, each requiring additional metabolic processes to maintain.

Increased human height (due to better nutrition) over the past century could have a similar effect–shorter men do seem to live longer than taller men, eg: 

Observational study of 8,003 American men of Japanese ancestry from the Honolulu Heart Program/Honolulu-Asia Aging Study (HHP/HAAS), a genetically and culturally homogeneous cohort followed for over 40 years. …

A positive association was found between baseline height and all-cause mortality (RR = 1.007; 95% CI 1.003–1.011; P = 0.002) over the follow-up period. Adjustments for possible confounding variables reduced this association only slightly (RR = 1.006; 95% CI 1.002–1.010; P = 0.007). In addition, height was positively associated with all cancer mortality and mortality from cancer unrelated to smoking. A Cox regression model with time-dependent covariates showed that relative risk for baseline height on mortality increased as the population aged. Comparison of genotypes of a longevity-associated single nucleotide polymorphism in FOXO3 showed that the longevity allele was inversely associated with height. This finding was consistent with prior findings in model organisms of aging. Height was also positively associated with fasting blood insulin level, a risk factor for mortality. Regression analysis of fasting insulin level (mIU/L) on height (cm) adjusting for the age both data were collected yielded a regression coefficient of 0.26 (95% CI 0.10–0.42; P = 0.001).

The more of you there is, the more of you there is to age.

Interesting: lots of data on human height.

But there’s another possibility involving internal temperature–since internal body temperature requires calories to maintain, people who “run hot” (that is, are naturally warmer) may burn more calories and tend to be thinner than people who tend to run cool, who may burn fewer calories and thus tend to weigh more. Eg, low body temperature linked to obesity in new study: 

A new study has found that obese people (BMI >30) have lower body temperature during the day than normal weight people. The obese people had an average body temperature that was .63 degrees F cooler than normal weight people. The researchers calculated that this lower body temperature—which reflects a lower metabolic rate—would result in a body fat accumulation of approximately 160 grams per month, or four to five pounds a year, enough for the creeping weight gain many people experience.

There’s an interesting discussion in the link on thyroid issues that cause people to run cold and thus gain weight, and how some people lose weight with thyroid treatment.

On the other hand, this study found the opposite, and maybe the whole thing just washes out to women and men having different internal temperatures?

Obese people are–according to one study–more likely to suffer mood or mental disorders, which could also be triggered by an underlying health problem. They also suffer faster functional decline in old age:

Women had a higher prevalence of reported functional decline than men at the upper range of BMI categories (31.4% vs 14.3% for BMI > or =40). Women (odds ratio (OR) = 2.61, 95% confidence interval (CI) = 1.39-4.95) and men (OR = 3.32, 95% CI = 1.29-8.46) exhibited increased risk for any functional decline at BMI of 35 or greater. Weight loss of 10 pounds and weight gain of 20 pounds were also risk factors for any functional decline.

Note that gaining weight and losing weight were also related to decline, probably due to health problems that caused the weight fluctuations in the first place.

Of course, general physical decline and mental decline go hand-in-hand. Whether obesity causes declining health, declining health causes obesity, or some underlying third factor, like biological aging underlies both, I don’t know.

Anyway, I know this thought is a bit disjointed; it’s mostly just food for thought.

Can Ice Packs Stop A Seizure? (epilepsy)

Source: WHO infographics on epilepsy

Ice packs (cold packs) applied to the lower back at the first sign of a seizure may be able to halt or significantly decrease the severity of a seizure.

(If I’m correct, then this is the most important post on this blog, so please share.)

After researching ways to stop seizures, I suggested this to a friend with epilepsy. Her previous seizure lasted for 5 minutes (absolutely terrifying); this time her husband ran to the fridge, got two ice packs on her back, and the seizure immediately began slowing.

Obviously this is only an anecdote, but if you or a loved one has seizures, I can’t imagine it would hurt to try.

Let’s run through the evidence in favor of ice packs:

Seizures can definitely be triggered by being too hot–febrile seizures are somewhat common in children with fevers. Hyperthermia (heat stroke) can also cause seizures. And, yes, you can induce seizures in rats by heating them up. In the rat experiment, note that the seizure-prone rats’s temperatures went up more than the seizure-resistant rats–seizures may be more common in people whose bodies have difficulty regulating their temperatures.

Seizures also independently increase brain temperature in rats, and preventing this temperature increase, at least during hypoxic seizures, appears to protect rats against brain damage. But these are rats, obviously, not humans.

“Status epilepticus” is a seizure that lasts for more than 5 minutes or that recurs within a 5 minute period, and is considered a life-threatening emergency. 10-30% of people with status epilepticus die within 30 days. The immediate treatment for such cases is of course with anti-seizure medications, but some seizures (refractory status epilepticus) don’t even respond to this. In these cases, hypothermia–cooling the patient–appears to stop the seizures. (At least until the patient warms up again, but this gives doctors time to work out a better treatment plan.)

That said, seizure-prone people don’t need to be cold all the time–summer weather doesn’t cause an overall uptick in seizures (and some people’s seizures are actually triggered by being cold. If you are one of these people, ice packs may not be for you.)

I encountered the ice packs trick on forums where people were talking about treating seizures in dogs. (Yes, there are dogs with epilepsy.) There are many accounts of people successfully stopping or preventing their dogs from going into a seizure by grabbing a cold pack at the first warning signs and putting it directly onto the dog’s lower back:

We have a precious little Jack Russell Terrier named Scamp. … he is one of many dogs who have epilepsy. This has broken our hearts over the last three-and-a-half years. …

Recently my husband and I did research on the Internet regarding dogs with epilepsy. What we found was amazing. Something the eight or so vets we have seen over the past years had never even mentioned to us. It’s as simple as keeping a bag of ice in your freezer.

We had never tried this until this morning at 5:00 a.m. when Scamp began seizuring. I’ve never seen anything work so fast in my life. As I write this this morning I’m still amazed and can’t believe that what ended a seziure was as simple as a bag of ice and 2 teaspoons of vanilla ice cream to elevate his blood sugar level.

Here’s how it works: all you do is fill a food storage bag (at least one quart size) with crushed ice and leave it in the freezer. When your dog starts to seizure remove the bag of ice from the freezer and place it firmly on his lower back. Scamp came out of his seizure in about 30 to 60 seconds. …

He came out of the seizure smoothly and with no post-ictal symptoms whatsoever. He began to walk and followed my husband and I right into the kitchen. I went to the freezer and took out vanilla ice cream and took two teaspoons out of the carton. … he lapped it up. He was fine. He wanted to go outside so my husband followed him out to make sure he would be OK. He went to the bathroom, roamed around the yard for a bit and came in and went back to sleep on our bed. I’m still in shock.

The ice cream is to help get the dog’s blood sugar levels back up to normal. Humans might also find this useful.

Here’s another testimonial, from one of the links above:

We have been using ice packs to help manage our girl’s seizures for over a year now. From what I have heard first hand from others is that it either doesn’t work at all or it works fabulously. With our girl it “works fabulously”. It is not the miracle cure and it does not prevent future seizures but it definitely stops her grand mal right in its tracks. It is the most amazing thing I have ever seen. I would love to get it on video but as you all know a seizure is such a highly emotionally time that grabbing the camera is the last thing on my mind. If we get the ice pack on her within the first 15 seconds or so, the grand mal just suddenly stops. Like a light switch. All motor movement comes to a halt. She continues to be incoherent for a bit but all movements stop.

“Lani” is a 65 lb. Lab with a pretty thick coat. Our first attempts did not go so well because those little blue ice packs or baggies did nothing. So I custom made her packs using large seal a meal bags with water and rubbing alcohol that I keep in the freezer. It is perfect because its super cold but pliable so you can form it over their back. Every seizure she has is treated with the ice packs. She is also on high doses of meds, supplements, etc. but my personal belief is that the ice pack treatment helps to significantly reduce the length of the seizure.

The Journal of American Holistic Veterinary Medical Association published an article on the use of ice packs to stop seizures in dogs, A Simple, Effective Technique for Arresting Canine Epileptic Seizures, back in 2004. You can read it for a mere $95, or check out the highlights on Dawg Business’s blog:

Fifty-one epileptic canine patients were successfully treated during an epileptic seizure with a technique involving the application of ice on the back (T10 to L4). This technique was found to be effective in aborting or shortening the duration of the seizure.

And of course, in a study of rat seizures, the cold rats didn’t have any while the warm rats did.

The technique doesn’t work for all dogs, but it works for enough that it really seems like there must be something there.

But I haven’t read any cases of people using ice packs to treat seizures in humans–the (small quantity of) veterinary literature doesn’t appear to have made it over to human trials. But if it works for dogs, why not try it on people? It would be simplest, cheapest, least side-effect-inducing option for millions of people whose seizures can’t be fully controlled by medication.

Why does it work?

I don’t know. The ice packs probably aren’t in contact with the dogs for long enough to significantly lower the dog’s brain temperature, although they might lower the temperature of spinal nerves.

Perhaps the sudden cold just has an overwhelming effect on the brain that interrupts whatever feedback loop is causing the seizure.

From The Hidden Genetics of Epilepsy

Why not just medicate the seizures away?

Seizures are serious, potentially life-threatening conditions (actually, a friend of the family who had epilepsy died of a seizure that occurred while taking a bath.) Seizure medications, by necessity, are also serious and can have major side effects. According to the WHO, 70% of epileptics respond well to medication and live normal lives–leaving 30% of people who don’t. For many people, especially children, treatment is about trying to find a balance between minimizing harm from seizures and minimizing harm from anti-seizure medications.

So for anyone out there with epilepsy or another seizure condition, please consider ice packs as one more tool in your arsenal. And for any doctors out there, please do some research on this; there’s got to be some medical award for anyone who can prove it.

Good luck.

Do Chilblains Affect Blacks More than Whites?

toes afflicted with chilblains
toes afflicted with chilblains

While tromping through a blizzard, seeking insight into circum-polar peoples, I discovered a condition called chilblains. The relevant Wikipedia page is rather short:

Chilblains … is a medical condition that occurs when a predisposed individual is exposed to cold and humidity, causing tissue damage. It is often confused with frostbite and trench foot. Damage to capillary beds in the skin causes redness, itching, inflammation, and sometimes blisters. Chilblains can be reduced by keeping the feet and hands warm in cold weather, and avoiding extreme temperature changes. Chilblains can be idiopathic (spontaneous and unrelated to another disease), but may also be a manifestation of another serious medical condition that needs to be investigated.

The part they don’t mention is that it can really hurt.

The first HBD-related question I became interested in–after visiting a black friend’s house and observing that she was comfortable without the AC on, even though it was summer–is whether people from different latitudes prefer different temperatures. It seems pretty obvious: surely people from Yakutsk prefer different temperatures than people from Pakistan. It also seems easy to test: just put people in a room and give them complete control over the thermostat. And yet, I’d never heard anyone discuss the idea.

Anyway, the perfunctory Wikipedia page on chilblains mentioned nothing about racial or ethnic predisposition to the condition–even though surely the Eskimo (Inuit) who have genetic admixture from both ice-age Neanderthals and Denisovans:

“Using this method, they found two regions with a strong signal of selection: (i) one region contains the cluster of FADS genes, involved in the metabolism of unsaturated fatty acids; (ii) the other region contains WARS2 and TBX15, located on chromosome 1.” …

“TBX15 plays a role in the differentiation of brown and brite adipocytes. Brown and brite adipocytes produce heat via lipid oxidation when stimulated by cold temperatures, making TBX15 a strong candidate gene for adaptation to life in the Arctic.” …

“The Inuit DNA sequence in this region matches very well with the Denisovan genome, and it is highly differentiated from other present-day human sequences, though we can’t discard the possibility that the variant was introduced from another archaic group whose genomes we haven’t sampled yet,” Dr. Racimo said.

The scientists found that the variant is present at low-to-intermediate frequencies throughout Eurasia, and at especially high frequencies in the Inuits and Native American populations, but almost absent in Africa.

Sub-Saharan Africans have their own archaic admixture, but they have very little to no ice-age hominin–which is probably good for them, except for those who’ve moved further north.

Imagine my surprised upon searching and discovering very little research on whether chilblains disproportionately affects people of different races or ethnicities. If you were a dermatologist–or a genetically prone person–wouldn’t you want to know?

So here’s what I did find:

The National Athletic Trainers Association Position Statement on Cold Injuries notes:

Black individuals have been shown to be 2 to 4 times more likely than individuals from other racial groups to sustain cold injuries. These differences may be due to cold weather experience, but are likely due to anthropometric and body composition differences, including less-pronounced CIVD, increased sympathetic response to cold exposure, and thinner, longer digits.3,6

I think CIVD=Cold-Induced Vasodilation

The Military Surgeon: Journal of the Association of Military Surgeons of the United States, Volumes 36-37, states:

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The text continues with descriptions of amputating rotting feet.

A PDF from the UK, titled “Cold Injury,” notes:

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Notice that the incidence of chilblains is actually less in extremely cold places than moderately cold places–attributed here to people in these places being well-equipped for the cold.

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Finally I found a PDF of a study performed, I believe, by the US Military, Epidemiology of US Army Cold Weather Injuries, 1980-1999:

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While I would really prefer to have more ethnic groups included in the study, two will have to suffice. It looks like trench foot may be an equal-opportunity offender, but chilblains, frostbite, and other cold-related injuries attack black men (at least in the army) at about 4x the rate of white men, and black women 2x as often as white women (but women in the army may not endure the same conditions as men in the army.)

On a related note, while researching this post, I came across this historic reference to infectious scurvy and diabetes, in the Journal of Tropical Medicine and Hygiene, Volumes 4-5 (published in 1902):

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Note: this is why it is important to discard bad theories after they’ve been disproven. Otherwise, you kill your scurvy victims by quarantining them instead of giving them oranges.