Wednesday, September 21, 2011

Walking through traffic fumes 'can raise risk of heart attack for six hours' (?)

This is a very ambitious study, correlating the TIME of heart attacks with the known level of pollution in the air at the time. Journal article here.

It seems unlikely that epidemiological data can answer the question asked. A firm conclusion would depend on the time of each person's heart attack being known and accurately given in official records -- a very dubious assumption. On the other side of the correlation, the air quality data is taken from the UK National Air Quality Archive. Is that archive specific enough to record what exposure EACH PERSON had to pollution? Surely not. Just being indoors versus outdoors could have a large effect.

The only cautious conclusion we could draw from the results reported is that they are a random walk

Higher levels of air pollution can increase the risk of having a heart attack for up to six hours after exposure, warn UK researchers. Even moderate levels of pollution from traffic carry an extra risk, according to a new study in the British Medical Journal.

The findings come from a detailed analysis of almost 80,000 heart attack cases and the level of pollution to which they were exposed.

Air pollution is currently estimated to reduce the life expectancy of everyone in the UK by an average of seven to eight months, probably by affecting the heart and lungs.

In the latest study Krishnan Bhaskaran, an epidemiologist from the London School of Hygiene and Tropical Medicine, and colleagues found rising air pollution was linked to a rise in heart attacks up to six hours after exposure. However, there was no increased risk after the six-hour period, with the number of heart attacks then falling to a lower level than expected.

The researchers reviewed 79,288 heart attack cases from 2003 to 2006 and exposure, by the hour, to pollution levels. They used the UK National Air Quality Archive to investigate the levels of specific pollutants in the atmosphere. These included pollutant particles (PM10), carbon monoxide (CO), nitrogen dioxide (NO2), sulphur dioxide (SO2) and ozone. Higher levels of PM10 – tiny toxic particles - and NO2 are well-known markers of traffic related pollution from vehicle exhaust fumes, said Dr Bhaskaran.

National air pollution warnings on weather reports alert people to changes using bands ranging from low, to moderate, to high, to very high. People who are sensitive to air pollution are advised to spend less time outdoors during high and very high episodes of air pollution, and not to exercise, along with those suffering asthma and heart disease.

Dr Bhaskaran estimated there would be an extra five per cent risk of a heart attack caused by a change in air pollution from ‘low’ to ‘moderate’ in the following six hours. The risk would increase further during ‘high’ and ‘very high’ episodes but they are uncommon in Britain, he added.

Dr Bhaskaran said the data suggested that after the first six hour period following pollution peaks, the number of heart attacks was lower than expected. Some people who were going to have a heart attack in that later period may have simply had their heart attack brought forward by a few hours as result of the pollution exposure, he said.

‘We know from many studies that there are more deaths when pollution levels are higher, but whether heart attacks make a major contribution to this is not clear.

‘Although we found a short period of increased risk of heart attacks in the few hours after air pollution peaks, the risk was small and had little net impact on the overall number of heart attacks’ he added.

Professor Jeremy Pearson, Associate Medical Director at the British Heart Foundation, which co-funded the study, said: ‘This large-scale study shows conclusively that your risk of having a heart attack goes up temporarily, for around six hours, after breathing in higher levels of vehicle exhaust.

‘We know that pollution can have a major effect on your heart health, possibly because it can "thicken" the blood to make it more likely to clot, putting you at higher risk of a heart attack.

‘Our advice to patients remains the same – if you’ve been diagnosed with heart disease, try to avoid spending long periods outside in areas where there are likely to be high traffic pollution levels, such as on or near busy roads.’

The study looked at heart attacks in England and Wales.


Electric-shock therapy lifted me from the hell of depression

There is a strong body of thought that the good attention that medical staff give to the patient while conducting the electroshock procedure is the curative influence -- a type of placebo effect. The fact that a series of treatments is needed before any progress is seen supports that view

Life for Tania Gergel could not have been more thrilling. Captivated by academic study, she quickly became one of the highest-achieving students on her Classics degree course at Bristol University, finding time to play percussion with several bands and orchestras, too. Tania, then 19, also met and fell in love with Matthew, a maths student, now her husband.

Then tragedy struck: the couple just returned from their first holiday together when Tania was told that her best friend, Ali, had been killed in a car accident. ‘It was a terrible shock — as though a screen suddenly came down between me and the rest of the world,’ recalls Tania, now 38, from North London. ‘After the funeral, when I went back to university, I felt detached from everyone. My mind had started racing and I couldn’t sleep.’

Within a month, Tania had stopped studying altogether. ‘I remember sitting in a common room waiting for a lecture. It felt like everything was swimming around me and I had to get out of the building.’

Tania was experiencing depression, specifically an episode of bipolar disorder, previously known as manic depression. According to the NHS, around 500,000 Britons have been diagnosed as bipolar, although recent studies suggest the true incidence may be more than five million. Sufferers typically swing between two phases — manic and depressive.

During the manic phase they may experience feelings of euphoria, talk at extreme speed and go for days without food or sleep. The depressive phase is characterised by severe low mood, a loss of sense of purpose and, at its most extreme, thoughts of suicide.

Several weeks after her friend’s death, Tania sought help from her GP who prescribed tricyclic anti-depressants — the standard treatment at that time. ‘It was a shock to be diagnosed with depression,’ she recalls. ‘When the doctor prescribed medication, I realised something was very wrong with me.

‘I’ve since learned that my grandmother had been hospitalised twice for psychiatric depression: she had heard voices.’ (There is strong evidence for a genetic vulnerability to developing the illness.)

However, after five months of taking anti-depressants, Tania was forced to acknowledge they were having no effect. ‘The depression got worse. I was getting two hours’ sleep at night, if that, invariably with sleeping pills involved. ‘I gave my pills to Matthew to look after as I felt I couldn’t trust myself any more not to take them all as an overdose.’

Eventually, Tania went as a voluntary inpatient to a private psychiatric hospital in London, where she stayed for two months. But despite being given every type of major antidepressant, nothing seemed to help and Tania and her family became desperate.

Then, by chance, Tania met a friend of a friend who was a psychiatrist at London’s Charter Nightingale Hospital (now Capio Nightingale). ‘He said it was clear the drugs weren’t working and suggested I come off all the pills and have electroconvulsive treatment.’

Many will recoil at the thought of electroconvulsive treatment (ECT), which was famously depicted in the 1975 Jack Nicholson film One Flew Over The Cuckoo’s Nest. But it is considered an effective treatment for severe depression which is resistant to medication and talking therapies such as Cognitive Behavioural Therapy.

About 20 per cent of all depression sufferers fall into this category, of which more than half would benefit from ECT, says Dr Cosmo Hallstrom, consultant psychiatrist at the Royal College Of Psychiatrists in London.

The treatment involves sending an electric current through the brain, under general anaesthetic, to cause a fit. Although it is not exactly known how it works, one theory is that the fit triggers certain brain chemicals, including the ‘feel-good’ chemical, serotonin, which is thought to be depleted in patients with severe depression.

The treatment was first introduced around 70 years ago but it fell out of favour following the introduction of antidepressant medication in the Fifties and Sixties.

In the past, ECT has been used indiscriminately, at times under duress and without general anaesthetic. As a result, it remains the most controversial treatment in modern psychiatry.

Indeed earlier this year the British Psychological Society called for it to be banned, describing the treatment as ‘inhumane and degrading’, and having only a short-term effect on people with manic depression.

However, many clinical studies show ECT is significantly more effective than antidepressants in inducing a speedy remission for severe treatment-resistant depression, says Dr Hallstrom. ‘It can cure a particular bout of depression — although it does not prevent relapses,’ he says.

Indeed, it is even recommended by the National Institute For Health And Clinical Excellence (Nice).

In 2008 Nice published guidelines on the management of bipolar disorder, which recommended ECT ‘to achieve rapid and short-term improvement of severe symptoms after an adequate trial of other treatment options has proven ineffective and/or when the condition is considered to be potentially life-threatening’.

Tania’s brother, then a practising psychiatrist, had himself carried out ECT many times and told her he had seen it have remarkable results. ‘He was very much in favour,’ she says. ‘You know your own brother has your best interests at heart.’

‘It wasn’t what people may think — being restrained in some sort of straitjacket. It was all very civilised. You go under a general anaesthetic for a few minutes and that’s really all you know.’

Dr Hallstrom says patients see an improvement after six twice-weekly treatments. Tania started to feel things changing after five. ‘It was a very sudden thing. I just woke up one day and thought: “I feel like something’s lifted.” Suddenly you’re released from internal torment.’

Six months after completing her course of ECT, Tania returned to her studies and got a First.

The treatment is not risk-free — half of those who undergo it experience side-effects, such as confusion and disorientation, after each treatment. ‘But this tends to fade after a few days,’ says Dr Hallstrom.

A trial is under way in Australia on a new form of ECT, which involves running an electric current through the brain for less time, and has been shown to have less of an effect on memory.

Tania had some memory loss in the period during which she received ECT, ‘but nothing really substantial’ she says. Indeed, after university she went on to gain a Masters and eventually a PhD in Classics, and fulfilled her dream of teaching.

For 11 years, she remained off medication and had no contact with any psychiatrist. Tania and Matthew married and had a daughter who is now seven.

ECT does not cure the problem for good, though, as Tania discovered. When her daughter was two, she became pregnant again. But then she miscarried, plunging her into a severe depression.

‘Within three weeks I was in hospital. My consultant psychiatrist suggested I try ECT again. It worked and after six treatments, all of a sudden I didn’t feel suicidal any more.’

Dr Hallstrom believes more people suffering with severe, medication-resistant depression should be given the option of ECT.‘It can be a lifesaver,’ he says.

Tania can only agree. ‘ECT won’t cure you, but it will get you out of the crisis state,’ she says. ‘Hands down I owe my life to ECT.’


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