Mind over mortality

Can the will to live triumph death and disease?

This is a difficult theory to test. Since it is impossible to predict exactly when someone will die, it is not possible to see if a will to survive will keep them alive longer.

A number of studies have looked at personality variables such as positivity and calmness on longevity. These have shown that contentedness, both early and late in life is linked to slightly longer life spans. Indeed mortality rates for the neurotic, unhappy and angry elderly people were often more than twice that of their contented peers.

It is possible that happier people have a stronger will to live. Or, conversely, that healthier people (who are more likely to live longer) are happier.

But happiness should not necessarily translate into a stronger will to live. Hasn’t everyone heard of the grumpy old grandfather hanging on just to spite the relatives? It could be that reduced mortality in the chirpy set is due to the health benefits of stress reduction.

So how could you test the will to live? Scientists have looked for occasions people may wish to live for. Religious, cultural or family-oriented days may provide a focal point – perhaps grandpa can will himself to live until his birthday so that he can see his family once again.

Thus a number of studies have looked at death rates before and after major events. These have included birthdays, Christmas, Passover and Chinese lunar celebrations. By testing specific events which are only important for a selection of the population at any one time, mortality rates can be compared between those for whom it may be important, and those for whom the date is irrelevant.

Many studies have demonstrated reduced death rates prior to such occasions, with a significant surge directly after the event. The importance of these events has apparently delayed deaths from diseases including cancer and heart disease.

No clear mechanism is obvious. Possible explanations have included reduced stress levels, better adherence to medication schedules, benefits of companionship or some psycho-biological process as a results of religious or emotional feelings.

There are confounding factors. Many of these events involve over-indulgence and high fat meals are known to cause heart attacks. Also, the holidays can be very stressful. This could lead to slightly higher death levels after the holiday. Only a few studies take into account the cause of death. Road deaths from drink driving or celebratory shootings (this is an American term relating to people accidentally killed when people shoot guns to celebrate holidays) and other such seasonally affected events may skew calculations.

Indeed reanalysis of the data presented in many of these accounts often alters the conclusions. Secondary research re-examining the spread of diseases covered, the specific time periods before and after an event and the calculation of the mortality percentages seems to deny any effects of willpower.

So, while tantalising, the evidence is not conclusive. Though, if I were a betting person, I would put money on willpower overcoming death in the short term. From personal experience I have seen the terminally ill hang on months beyond the best estimates of doctors, only to fade fast when they suddenly lose the will to survive.

References

Skala JA, Freedland KE (2004) Death takes a raincheck Psychosom Med. 66(3):382-6.

Danner DD, Snowdon DA, Friesen WV (2001) Positive emotions in early life and longevity findings from the nun study. J Pers Soc Psychol 80: 804–13

Lee P, Smith G. (2000) Are Jewish deathdates affected by the timing of important religious events? Soc Biol. 47(1-2):127-34.

Phillips DP, King EW (1988) Death takes a holiday: mortality surrounding major social occasions Lancet 2(8613):728-32.

Phillips DP, Smith DG (1990) Postponement of death until symbolically meaningful occasions JAMA 263(14):1947-51.

Smith G. (2004) Asian-American deaths near the Harvest Moon Festival.
Psychosom Med 66(3):378-81.

Wilson RS, Bienias JL, Mendes de Leon CF, Evans DA, Bennett DA (2003) Negative affect and mortality in older persons Am J Epidemiol. 158(9):827-35.

Wilson RS, Mendes de Leon CF, Bienias JL, Evans DA, Bennett DA (2004) Personality and mortality in old age J Gerontol B Psychol Sci Soc Sci 59(3):P110-6.

Young DC, Hade EM. (2004) Holidays, birthdays, and postponement of cancer death.
JAMA 292(24):3012-6.

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Cocktails and hearing aids

It’s a Saturday night and you are going out. You can hear the bass beat a block before you get to the party. As you walk into the house, you are surrounded by people talking, the clinking of glasses and the ever-present music. Waving at you, the host appears and asks “What would you like to drink?”

It’s a common enough opening, and the interesting part is not the drink of choice, but how you could understand the question.

Every day, in buses, trains, crowded restaurants and open plan offices, most people easily understand other people talking. It hardly seems exciting and yet it has fascinated scientists for over half a century – ever since Cherry first described “the cocktail party problem”. The mechanisms underlying this talent are still not fully understood.

Why is it such a mystery?

The ear hears by collecting soundwaves and passing them along the ear canal, though a series of small bones, to the inner ear, where the soundwaves vibrate the basilar membrane (a tiny organ curled inside the spiral cochlear). The basilar membrane tapers along its length and different parts vibrate depending on the frequency of the sound waves. The narrow end vibrates in response to high frequencies (high pitch sounds), and the wide end to low frequencies (low pitch sounds). Hair cells pick up the vibrations and pass them along into the brain.

Since sounds are comprised of a number of frequencies (the average human voice ranges from the buzz of a mosquito to the highest note on a piccolo), all sounds sum to create the vibrations. Thus your brain knows only which frequencies are present in a room of noise, not which frequencies belong to the person you are trying to hear.

So how can we isolate just one person?

The tempo of their speech is different from that of the music, the conversation flows unlike the sporadic clink of glasses; they may have a lovely accent or a deep voice. Similarly hand gestures, facial expressions and lip movements also add to the experience. All of these speech cues can help you work out which sounds belong to the person you are listening to and which to unwanted intrusions.

Expectation is a factor. When someone is speaking about the latest football results, you can safely ignore any words and phrases relating to politics.

Having two ears also helps. Speech coming from a person on your left side will hit your left ear first and be louder in that ear than in the right ear. The brain can then use that time and volume difference to separate frequencies belonging to that person from those belonging to someone standing on your right.

But all this is done without thought. Can you consciously help?

How often have you missed a sentence because you “weren’t paying attention”? Concentrating on a person makes it easier to follow them. But when you concentrate on understanding a person, are you attending to their accent? their location? the cadence of their speech? or a mix of everything? Experiments are currently trying to work out which factors you can attend to and how this attention can make understanding easier. For example, do you increase your brain responses to speech when you are paying attention or do you just put more resources into interpreting the responses you subconsciously receive?

Who cares HOW you understand since it’s so easy?

If you don’t already, you will. As you age you will slowly lose the ability to listen to a friend in a noisy environment. This is the greatest hearing-related complaint from the aged and from hearing aid users.

Until we understand how a person with normal hearing can solve the cocktail party problem, we cannot work out what is going wrong as people age, nor can we design better hearing aids or assist those with impairments.

So next time you are offered a drink at a noisy party, spare a thought for your auditory system. Chances are its miracles are being wasted on acquiring luke-warm chardonnay.

References

This is the topic of my thesis, so to date I have well over 200 references. They would not all fit here, so I shall limit the list to the original paper that started the scientific debate:

Cherry EC (1953) Some experiments on the recognition of speech, with one and with two ears. J. Acoust. Soc. Am. 25: 975-979

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Better salad dressings II – natural emulsifiers and creamy milk

To make more stable salad dressings (see previous post), you need a chemical which can help to suspend the oil particles in the water-based liquid. Mustard and cayenne pepper are natural emulsifiers which can help to suspend oil in water. Adding these to a vinaigrette will slow the mix from separating after you shake it.

Egg yolks (these contain lecithin) are used to emulsify mayonnaise. It’s easy to test how good an emulsifier these are by shaking them with a little water and oil and seeing how long the mixture takes to settle back into layers.

Milk is a mix of fats and liquids. If you leave fresh milk to sit for a while, the fat will eventually settle out, leaving a cream layer. This can be collected for sale as cream, or used to make butter. To prevent this, milk for drinking is homogenised. This involves forcing the milk at high pressure through a narrow opening. Cream globules are broken into very small droplets. These have larger surface areas, and are more spread out throughout the milk. This and the emulsifiers naturally found in milk (including casein and lecithin) allow the cream to stay evenly distributed throughout the liquid for longer.Thus the milk you buy in the supermarket does not have a cream layer even when left to stand for a few days.

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Mummy, why can’t I swim straight after lunch?

When you eat, blood moves to surround the intestinal tract ready to absorb the nutrients from the meal. This reduces the blood available to the extremities, such as the arms and legs.

Blood carries oxygen and energy to muscular tissues and removes waste products for recycling. When blood flow is sufficient, muscles can continue to work in relative comfort. Where muscles work too hard, or blood flow is reduced, waste products build up creating acid. This causes painful cramps – the ubiquitous “stitch”.

Since blood flow is reduced to active muscles after eating, the risk of cramps increases. On land this is no great problem. Taking deep breaths and allowing oxygenated blood to flow to the site of the cramp soon clears any pain. In the water, it is possible that a person may drown before the cramp clears. This is particularly true in very cold water, where blood flow may be withdrawn from peripheral tissues to maintain core temperature (see previous post), further reducing the amount of blood available to swimming muscles.

However you do need to be very active to deplete available blood resources. Swimming a race is risky, but lazing around in a backyard pool is probably fine. Though if you are worried, waiting an hour after eating before swimming should negate the slight increase in risk.

To see the results of eating on muscle function, you can test yourself by going for a run before and after eating a large meal. You will probably notice muscular cramps or a stitch forming faster after eating.

Mind you, eating a heavy meal can also make you nice and sleepy. Which for me means that I don’t feel like either swimming or running straight after lunch.

References

Mao CC, Jacobson ED. (1970) Intestinal absorption and blood flow. Am J Clin Nutr. 23(6):820-3.

Spring B, Chiodo J, Harden M, Bourgeois MJ, Mason JD, Lutherer L. (1989) Psychobiological effects of carbohydrates. J Clin Psychiatry. 50 Suppl:27-33.

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Tipsy on bubbly

Champagne has no more alcohol than many wines, yet most drinkers notice that you feel tipsy faster.

It’s not just a feeling. One study suggests that the blood alcohol levels rise more quickly after drinking champagne (or any sparkling wine) compared to a still wine. This increased impairment lasts for 20 minutes, until still wine drinkers “catch up” with the inebriation levels.

Why would this be?

Flattened champagne acts like a regular wine, so it must be something to do with the bubbles.

Bubbles in sparkling wines are carbon dioxide. In expensive wines, these are a product of active yeast. In cheaper wines, this is artificially added, in the same way as soft drinks are carbonated.

So how does carbon dioxide bubbles help to move alcohol into the bloodstream?

Very little alcohol passes through the stomach walls, most is absorbed from the small intestine. It is possible that bubbles push against the sphincter muscle closing the stomach, encouraging it to open and permit faster gastric emptying. Since alcohol would then hit the small intestine earlier, it could be absorbed more quickly.

It really needs more research. I’m sure there would be no shortage of volunteers for studies looking at relative rates of inebriation.

But this raises some extra questions. Does fizzy beer make you drunk faster than still? What about sparkling cocktails versus still ones? Do carbonated soft drinks raise blood glucose levels more quickly than flat cordials?

Plenty of research ideas for the budding scientist (alcoholic?).

Reference

Ridout F, Gould S, Nunes C, Hindmarch I. (2003) The effects of carbon dioxide in champagne on psychometric performance and blood-alcohol concentration. Alcohol Alcohol. 38(4):381-5.

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A healthy marriage

Numerous studies have looked at life expectancy and marital status. Even after social and economic factors (such as poverty and education) are factored in, it seems that married people (particularly men) live longer than their unmarried peers.

Marriage (and to some extent long term defacto relationships) have been routinely linked to lower rates of heart disease, reduced risk of accident and suicide and even (in some instances) a decreased likelihood of cancer and stroke.

People who never marry generally seem to be the least healthy. Those who are widowed or divorced also show increased mortality rates, particularly in the couple of years directly after losing their spouse. This is particularly true for those in their 20s and 30s.

What could cause this?

Perhaps researchers could be confusing cause and effect. Maybe the old adage “all the good ones are taken” is true? Research has certainly shown that those people who don’t marry have comparatively low levels of education and are more likely to be out of work. Perhaps healthier and more successful people make more attractive spouses?

This could explain the difference between the health of married and never-married people, but it doesn’t explain why people who used to be married are less healthy.

So it probably comes down to stress.

One possibility for stress reduction in marriage comes with a division of labour – in a couple, there are two people to share the work of gaining income, two people to divide costs and to share household chores etc.

Another reduction may come from the psychological benefits of having a spouse – someone to listen to your problems and provide regular sex. Perhaps marriage even strengthens the desire to look after yourself – encouraging you to keep in shape and work out to remain attractive.

A partner may also help to nurse you through minor illnesses, reducing long term health effects.

One of the strongest factors appears to be the presence of a social network. This extends beyond the spouse, and takes in friends, relatives and the entire community. Where people have strong networks, research has shown a reduction in cardiovascular disease and accidental/suicidal death. Marriage may help to provide such a network.

Certainly, as the proportion of people in one marital status group rise, the health benefits increase also. If you never marry, it is better to live in a community with a large number of other singles, than in one where everyone you know is coupled up.

The social stigma of being different to the norm seems to cause the problem. This even extends to children born out of wedlock. Again, people born to unmarried parents, particularly those who never marry have poorer health than their counterparts.

A note of warning though. An unhappy marriage may cause increased stress, so probably isn’t going to help.Thus any potential benefits can only come from marrying the right (type of) person.

References

Note: There is a huge amount of literature available on this topic, from all around the world. This is but a small subsection.

Ben-Shlomo Y, Smith GD, Shipley M, Marmot MG. (1993) Magnitude and causes of mortality differences between married and unmarried men. J Epidemiol Community Health. 47(3):200-5.

Ebrahim S,Wannamethee G, McCallum A, Walker M,Shaper AG. (1995) Marital status, change in marital status, and mortality in middle-aged British men. Am J Epidemiol.;142(8):834-42.

Hu YR, Goldman N. (1990) Mortality differentials by marital status: an international comparison. Demography. 27(2):233-50.

Janlert U, Asplund K, Weinehall L, Orth-Gomer K, Unden AL.(1992) Men who never married. A socio-medical study in northern Sweden. Arctic Med Res.;51(2):72-80.

Kaplan RM, Kronick RG.(2006) Marital status and longevity in the United States population. J Epidemiol Community Health.;60(9):760-5.

Kawachi I, Colditz GA, Ascherio A, Rimm EB, Giovannucci E, Stampfer MJ, Willett WC. (1996) A prospective study of social networks in relation to total mortality and cardiovascular disease in men in the USA. J Epidemiol Community Health.;50(3):245-51.

Mendes de Leon CF, Appels AW, Otten FW, Schouten EG. (1992) Risk of mortality and coronary heart disease by marital status in middle-aged men in The Netherlands. Int J Epidemiol.;21(3):460-6.

Modin B. (2003) Born out of wedlock and never married–it breaks a man’s heart. Soc Sci Med.;57(3):487-501.

Nilsson PM, Nilsson JA, Ostergren PO, Berglund G. (2005) Social mobility, marital status, and mortality risk in an adult life course perspective: the Malmo Preventive Project. Scand J Public Health. 33(6):412-23.

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Is your wife killing you?

The age of your wife may take years off your life.

Since 1688, the age of women getting married has risen slightly, while men are marrying at a slightly younger age. Much of this is due to changing social attitudes and the introduction of age of consent laws. Overall, this has led to a gradual reduction in the age difference between spouses.

A couple of studies have looked at the life expectancy of a husband as it relates to the age of his wife. It seems that men with younger wives live longer than men with older wives. the older the man is, the more this relationship holds true.

It is not linear, however – a really young wife will not ensure that you live to a ripe old age. The effects will even reverse if your wife is more than 25 years your junior. It has been theorised that with very large age differences, social disapproval can take away any potential benefits.

The jury is out on marriage to an older woman, with one study showing longevity benefits over husbands with wives the same age as themselves. The other study shows reduced life expectancy.

For women, younger husbands are also better. Women married to a younger man (up to 14 years her junior) live longer than those married to an older or same-aged husband.

Why would this be the case? One theory is that, just as spouses are supposed to grow to look like each other, they start to age like the other, averaging the biological age between the spouses. Perhaps the younger spouse helps to keep the older more physically and mentally active. There could be social or psychological benefits to having a younger spouse – perhaps an attractive young thing on your arm at office parties is more likely to get you promoted, for example.

But looking at statistics can confuse cause and effect. Perhaps marrying a younger person won’t keep you alive longer. Maybe you are just more likely to attract a younger spouse if you are biologically young, or very healthy. Certainly most people won’t marry an older person if they look like they’re going to die suddenly (unless they are very wealthy).

So don’t rush out for a younger model yet. At least read tomorrow’s post first…

References

Foster D, Klinger-Vartabedian L, Wispe L.(1984) Male longevity and age differences between spouses. J Gerontol. 39(1):117-20.

Kemkes-Grottenthaler A. (2004) “For better or worse, till death us do part” – spousal age gap and differential longevity: evidence from historical demography. Coll Antropol. 28 Suppl 2:203-19

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