BMJ  2006;333:90-91 (8 July), doi:10.1136/bmj.333.7558.90

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Older people sleep better after cognitive behaviour therapy

Up to a quarter of people aged over 55 sleep badly, and most of this insomnia remains untreated. Those that do ask for help are often prescribed drugs that don't work very well, or for very long. Cognitive behaviour therapy probably works better, according to a clinical trial from Norway that compared six weeks of therapy with six weeks of the popular drug treatment zopiclone, or a placebo.

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Using home polysomnography (electroencephalography, electromyography, electro-oculography) and sleep diaries, the researchers looked for changes in total sleep time, total wake time, sleep efficiency, and time spent in valuable slow wave sleep. Cognitive therapy looked significantly better than zopiclone for three of the four outcome measures, particularly sleep efficiency (ratio of total time asleep to time spent in bed), which went up from 81.4% to 90.1% in the therapy group (n = 18) and down from 82.3% to 81.9% in the zopiclone group over six months (n = 16). Those who had therapy also got significantly more slow wave sleep than either of the other groups, but no more sleep overall.

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The authors say their results are clinically meaningful as well as statistically significant, and consistent with previous work showing the benefit of cognitive behaviour therapy for younger adults with insomnia. Importantly, the benefits of cognitive behaviour therapy seem to last. The older people in this trial had individual therapy that included help with sleep hygiene and learning how to relax.

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JAMA 2006;295: 2851-8[Abstract/Full Text]

Outbreaks of rare fungal keratitis reported in Singapore, Hong Kong, and US

Fungal keratitis is a sight threatening infection that's only rarely associated with wearing contact lenses. So when ophthalmologists in Singapore noticed a dramatic increase in the number of cases, they alerted the health ministry, which in turn warned opticians and other health professionals to expect more.

A retrospective look through all public hospital records since the start of the outbreak found a total of 66 patients presenting in one year. All wore contact lenses and all were infected with a species of Fusarium that is ubiquitous in the tropics. Experts estimate that in a normal year there would be no more than five cases of this infection in Singapore and that all but one or two would be associated with trauma, not contact lenses.

It's too early to say what caused the outbreak, although researchers are investigating the possibility of a link with the ReNu brand of lens cleaner, used by 62 of the 66 patients discovered so far. This brand's market share in Singapore is thought to be about 30% to 40%, and the manufacturer was worried enough by the outbreak to withdraw its product from the market. Similar outbreaks have been reported in Hong Kong and the United States. Doctors elsewhere should stay vigilant, write the researchers.

JAMA 2006;295: 2867-73[Abstract/Full Text]

No drop in night-time blood pressure predicts heart failure in older men

In healthy people, blood pressure drops slightly during the night. Analysis of blood pressure data and hospital records from a long running cohort of older Swedish men found that those whose blood pressure failed to dip at night were significantly more likely than the others to develop heart failure.

The 951 men had no signs of heart failure when they joined the cohort, and the systolic blood pressure in most of them dropped at night to an average of 85% of their daytime systolic blood pressure. Those whose pressure didn't drop had a 21% increase in their risk of heart failure over nine years, once other risk factors including daytime blood pressure had been taken into account (hazard ratio 2.21 (95% CI 1.12 to 4.36). Night-time diastolic pressure was also independently linked to heart failure such that each 5 mm Hg increment increased the risk by 13% to 25% depending on the analysis.

We already know that a "non-dipping" blood pressure at night is a marker for cardiovascular disease in general, but the authors say theirs is the first study to show an independent link with heart failure, a common and lethal disease that costs developed countries an estimated 1% to 2% of their health budgets.

JAMA 2006;295: 2859-66[Abstract/Full Text]

Too much iodine is less harmful than too little

Iodine deficiency remains a worldwide problem with many associated hazards such as pregnancy loss, developmental delay, and goitre. Adding iodine to salt is one solution, but some governments are reluctant to make it mandatory because of fears that excess iodine could be harmful. To try to quantify the risks, researchers from China studied thyroid disease in three distinct regions: Panshan, where iodine intake is low; Zhangwu, where iodine intake is more than adequate; and Huanghua, where iodine intake is excessive because of the high iodine content in the drinking water. Salt has been iodised in China since 1996, so iodine intake was stable during the study.

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More than enough or too much iodine in the diet was associated with a slightly higher incidence of subclinical hypothyroidism over five years and also with a slightly higher incidence of autoimmune thyroiditis. But the researchers found no extra cases of overt hypothyroidism or hyperthyroidism in Zhangwu or Huanghua.

Although there could be small risks associated with large scale strategies to iodise salt, a linked editorial (pp 2819-21) says they are dwarfed by the much more serious risks associated with poor iodine intake. These findings should not prevent any government from taking action to prevent it. The World Health Organization estimates that about two billion people, including 285 million school aged children, are still iodine deficient.

N Engl J Med 2006;354: 2783-93[Abstract/Full Text]

Social disadvantage is probably responsible for half the health inequality in New Zealand

The indigenous population of New Zealand, the Maori, have a death rate roughly double that of the majority population, most of whom came originally from Europe. About half of this striking inequality is accounted for by social disadvantage, according to recent estimates. Smoking is to blame for less than a tenth. Epidemiologists from New Zealand arrived at these figures after a careful and detailed analysis linking census data from all adults aged 45-74 years old with mortality data from the three years after the census. They did it twice, to find out if effects of social disadvantage and smoking had changed over time.

Between the early 1980s and the late 1990s, the mortality gap between Maori and European populations widened, particularly among smokers. Smoking contributed most to the inequality between women, but for both sexes together it was less important than expected. Social disadvantage was a much bigger problem for everyone. Higher rates of unemployment, low incomes, poor educational achievement, and other measures of social disadvantage accounted for 37% of the excess mortality for men and 32% for women in the late 1990s. Both are almost certainly underestimates. The epidemiologists say the true contribution of social disadvantage is likely to be nearer 50%.

Lancet 2006;368: 44-52[CrossRef][Medline]

Lowering homocysteine doesn't improve cognition for healthy older volunteers

There's plenty of observational evidence linking high serum concentrations of homocysteine with poor cognitive function in older people. Homocysteine has even been implicated in the development of dementia. But attempts to improve cognitive function by reducing homocysteine concentrations have so far failed.

In the most recent clinical trial, two years of extra B vitamins (B-6 and B-12) and folate had the desired effect on homocysteine concentrations but had no discernible impact on any measure of cognitive function in 276 healthy older volunteers. The trial was randomised, double blinded, and placebo controlled and was powerful enough to find any clinically important difference in a comprehensive battery of cognitive tests. If anything, the vitamins seemed to make cognition worse, although the single significant result could have arisen by chance. All the volunteers started the trial with a relatively high plasma concentration of homocysteine (at least 13µmol/l).

Were all those observational studies misleading? A linked editorial and the authors agree that it's too early to say. This trial lasted only two years and could have ended before the real benefits appeared. The volunteers were healthy and well educated and had better than average cognitive function at the start. It's still possible that lowering homocysteine might work for people who are less mentally agile.

N Engl J Med 2006;354: 2764-72[Abstract/Full Text]

Diabetes ages arteries by about 15 years.

A cohort study including more than nine million Canadians has found that diabetes ages the cardiovascular system by about 15 years. Adults with type 1 or type 2 diabetes became "high risk" for a cardiovascular event around the age of 48 for men and 54 for women, those without diabetes crossed this threshold an average of 14.6 years later. For this analysis, the authors defined high risk as a 20% chance of heart attack, stroke, or death within the next 10 years. Generally speaking, adults with diabetes stayed at low (or at worst moderate) risk until their 40s.

Once they reached the age of 50, however, men with diabetes had a risk of heart attack or death roughly equivalent to the risk associated with established heart disease. In other words, having diabetes was about as dangerous as having a history of heart attack. The same was not true for women.

The study also showed that diabetes almost wipes out the cardiovascular protection associated with being female. Among adults without diabetes, the men were two and half times more likely to have a heart attack than women of the same age. Among adults with diabetes, the adjusted hazard ratio for men was reduced to 1.22 (95% CI 1.18 to 1.25).

Lancet 2006;368: 29-36[CrossRef][Medline]

Injuries are overwhelming the poor countries of Europe

Injuries are a much neglected public health problem, particularly in the low and middle income countries of eastern Europe, where injury rates are among the highest in the world. A report from WHO blames rapid social change for the worsening death toll and urges governments to put the safety of their populations much higher up the political agenda.

Overall, injuries rank third among the leading causes of death in the WHO European region and account for 9% of all deaths and 14% of all illness. But people in low and middle income countries are 3.6 times more likely to die from injuries than their richer neighbours. They are 17 times more likely to die from poisoning, 14 times more likely to die from interpersonal violence, and nine times more likely to drown. The epidemic is being fuelled by unemployment, poverty, social disintegration, and by alcohol, which is implicated in 40-60% of injuries, says the report.

Countries such as Sweden and the Netherlands are the safest in the world. More than 500 000 lives would be saved each year if the poorest countries in the region could match their mortality. Controlling alcohol misuse would be a start. One campaign in the Russian Federation cut alcohol consumption by a quarter, cut alcohol fuelled violent deaths by a third, and increased men's life expectancy by three years.

Lancet 2006 doi 10.1016/S0140-6736(06)68895-8

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