Science: Pinpoint the panic button

Panic attacks are seen as a particularly modern disease, a product of our stress-filled culture and hectic work schedules. Recent studies have shown that panic is not purely an hysterical overreaction to modern living but is caused by a brain abnormality which can be treated with Prozac-like drugs.

A typical panic attack is when you start to shake, sweat, feel nauseous and dizzy, and your heart begins to pump faster. These attacks can appear for no apparent reason, but if a person has more than one attack a week for over three weeks, they may be suffering from panic disorder. Often there is no recognisable trigger, but once someone has started having panic attacks, they may become linked to specific situations, such as travelling on the train or public speaking.

One in 10 people will have an attack at some point in their lives, but in about one in 50 people this will develop into a panic disorder. More women than men suffer from panic attacks, and the disorder is most prevalent in young people aged between 25 to 34.

Professor David Nutt, from the Psychopharmacology Department at Bristol University, believes that older people suffer less because their brains are less active. "In your twenties, your brain is at its most plastic and reactive," he says.

There are other contributing factors to the youthful nature of panic attacks. "People in their twenties are beginning to leave home, they're more isolated, they are facing adult life for the first time: it's a time when there's maximum pressure on them, and they no longer have the support of their families."

Although the term panic originally derives from the name of a Greek god, Pan, who could allegedly strike terror into the heart of man and beast alike, and loved to make strange sounds in the night, panic disorder is a modern disease.

This is partly because the condition has only been treated seriously during the last 20 years, but it may be on the increase due to our modern lifestyle, where we are surrounded by crowded and over-bright environments such as supermarkets and windowless office blocks. One theory is that an overload of sensory stimulation may trigger panic attacks; in addition, what many people are frightened of is not being able to escape.

Prof Nutt believes that panic disorders are caused by an over-production of chemicals in the brain that are designed to elicit a fight or flight response in the presence of danger. Normally a quick physical and emotional response to what might be a life-threatening situation is beneficial in evolutionary terms.

In our society women are particularly susceptible to panic. This may be because women often suffer from multiple stresses, such as trying to work and bring up a child, but the original biological reason could be linked to the hormone oestrogen. The evidence for this claim comes from studies of post-menopausal women who were given oestrogen during hormone replacement treatment and who started to suffer from panic attacks, either for the first time, or for the first time since the menopause.

"Oestrogen may turn on panic," says Prof Nutt, arguing that this link between oestrogen and panic could have evolved for a reason. "Young women who are reproductively active may be more prone to pay attention and show anxiety around children, which is advantageous."

There are several different kinds of anxiety caused by panic. One patient, who suffered from agoraphobia, the fear of open spaces, had to receive special permission to get married at home since she had been unable to leave the house for eight years. Many of us will have experienced social phobia to some extent - anxiety in social situations when all the attention is focused on oneself, such as public speaking. A social phobic finds panic-inducing situations worse when another person is with them; in a restaurant he or she will sit at the side or the back, whereas someone with panic disorder sits near the door.

Another kind is GAD, general anxiety disorder. This is chronic anxiety about things that, to a non-sufferer, seem trivial - being late for appointments, or not finishing homework. To the sufferer these problems seem insurmountable and, as a result, they often feel tense, irritable and can't sleep.

However, until now it was not known why some people suffer from any of these kinds of panic disorder. Initially researchers thought that a chemical produced in the brain triggered panic attacks, and that people who suffer from panic disorder produce excessive amounts of this chemical.

Prof Nutt and his colleagues gave patients a drug, Flumazenil, to block the chemical, but found out that it made them worse. Flumazenil has no effect on people who are not prone to panic, yet sufferers experience extreme attacks, sometimes their most severe to date.

At the same time, a drug called Clonazepam was discovered - this suppressed panic attacks and was known to work on the GABA system. GABA is gamma- butyric acid, which acts as a natural calming chemical, suppressing feelings of panic: reducing GABA increases anxiety. Nutt's hypothesis was that the GABA system might be malfunctioning in patients who are prone to panic. Together with Drs Andrea Malizia and Caroline Bell, also from Bristol University, and a team of researchers from Hammersmith Hospital, he took PET scans of patients who had been given Flumazenil. What these brain scans showed was that those people who suffered from panic attacks had abnormal GABA receptors, especially in parts of the brain associated with anxiety such as the temporal lobes and the orbitofrontal cortex. The receptors that were there did not bind with GABA efficiently.

Prof Nutt's theory looks as if it might be correct: people who are prone to panic do not have fully functioning GABA receptors, either because they were born that way - and evidence from animals shows that those which have altered GABA receptors are more anxious - or they have induced this brain state themselves. Alcohol, for example, initially increases GABA, but once drinking ceases, GABA release is inhibited. Stress also decreases GABA.

Nutt and Bell are now working on a range of drugs to treat panic disorders. Like Prozac, these drugs increase the brain's natural levels of serotonin. The two most effective drugs tested so far are Paraoxetine and Citalopram. Work that is currently underway suggests that regulating serotonin is important, but Prof Nutt is unsure whether GABA is affected by the drugs themselves, or as a result of the altered amounts of serotonin. Either way, it looks as if the study of panic may finally become a respectable science and those people who suffer from panic attacks can be helped.