91av

Read more: 鈥�The ultimate guide to memory鈥�

WHAT pushes someone to try to take their own life? That鈥檚 what psychologist Mark Williams was trying to find out as he visited people recovering from attempted suicide in the UK鈥檚 Addenbrookes Hospital in the 1980s. Williams knew he had to tread carefully: the patients had been hospitalised for an attempted overdose in the past 48 hours. 鈥淭hese people had done dangerous things to themselves,鈥� he recalls. 鈥淵ou can鈥檛 ask them to do complicated tests.鈥�

Williams was there because he suspected there was something different about the long-term memories of depressed or suicidal people, and had devised a simple exercise to test his theory on the patients at Addenbrookes. Sitting at their bedside, he would read out a cue word, such as 鈥渉appy鈥� or 鈥渃lumsy鈥�, before asking them to describe a past event it brought to mind. Perhaps not surprisingly, they were quicker to tell him about negative experiences than positive ones, but Williams was struck by something more subtle.

While his comparison group 鈥� other hospital patients who weren鈥檛 depressed 鈥� tended to focus on specific events, the overdose patients were noticeably vaguer. One responded to the word 鈥渉appy鈥� with 鈥渢he first years of my marriage鈥�, for instance; another person given the word 鈥渟afe鈥� said: 鈥渨hen I鈥檓 in bed鈥�. Even when Williams encouraged them to be more specific, they were less likely to dig out a single incident 鈥� such as a particular film, or an insult that had upset them.

It was as if the depressed patients were merely skimming the chapter headings of their autobiographies, without reading the text that followed. It might seem a minor detail compared with the desperation that leads to a suicide attempt. But 奥颈濒濒颈补尘蝉鈥檚 findings, which are now supported by a host of studies from other groups, have emphasised just how important our memories are in shaping our well-being, offering a new perspective on depression and perhaps other mental illnesses too.

Holding on

According to this theory, our memories act as a kind of ballast that holds us steady during times of stress; they can suggest ways to solve problems and offer comfort when we are feeling wounded. When people find it hard to recall specific events from their past, however, they feel overwhelmed by life鈥檚 challenges, which slowly pushes them into depression. 鈥淚n the right circumstances, the effect can be striking,鈥� says Williams, . If the theory is right, there may be new ways of treating depression that directly target the underlying memory problems.

鈥淢emories act as a kind of ballast that holds us steady during times of stress鈥�

A new approach would certainly be welcome. Depression is the commonest form of mental illness, affecting somewhere between 10 and 20 per cent of us at some point in our lives. Antidepressants help some people, particularly the most severely affected, but these drugs can bring side effects, including weight gain and loss of libido. Meanwhile, talking therapies such as cognitive behavioural therapy can be costly and often take weeks or months to make an impact.

Williams is by no means the first to suggest that memory plays a part in mental illness; Sigmund Freud once suggested that the repression of unpleasant memories from childhood could lead to hysteria. In the case of 奥颈濒濒颈补尘蝉鈥檚 suicidal patients, however, theirs was a more general difficulty. When questioned, they painted their past in broad brush strokes 鈥� 鈥淚 always enjoyed a good party鈥� that missed the details of specific events 鈥� 鈥渕y brother鈥檚 30th birthday鈥�.

奥颈濒濒颈补尘蝉鈥檚 , published in 1986 in the Journal of Abnormal Psychology, triggered a trickle, then a torrent, of similar studies. They revealed that 鈥渙ver-general memory鈥�, as the phenomenon came to be known, was not limited to people who had tried to commit suicide, but was linked to depression in general.

Further studies found it to be present before the low mood developed, lending weight to the idea that the memory problems led to depression and not the other way around. For instance, one team the memories and well-being of 74 women who had undergone IVF and failed to get pregnant. Those who had the least specific recall before the treatment were most likely to develop symptoms of depression after the disappointment. Another study, published in April, found that teenagers judged to have over-general memory were more likely to develop depression in the .

As the body of evidence supporting this idea has grown, various theories have emerged about just how memory problems could send our mood into a downward spiral. One idea is that remembering the good times is important for chasing the blues away. 鈥淭hinking of better times gives you more hope for the future,鈥� says Jennifer Sumner of Northwestern University in Evanston, Illinois. If you can鈥檛 remember those sunnier days, the future may seem very dark indeed.

Given the role of memory in imagination and foresight (see 鈥�Remembrance of things to come鈥�), poor access to our past may also impair our problem-solving skills, which are known to be weaker in depressed people. When asked how you might make friends after moving to a new neighbourhood, for example, most people can come up with good ideas, like inviting the neighbours round for drinks. Depressed people, in contrast, tend to be stumped by these questions. Importantly, people with over-general memory also seem to at this kind of task. 鈥淲hen you face problems in your life, you don鈥檛 have an analogy to help you solve the current situation,鈥� says . It is easy to imagine how, with your difficulties mounting, you may then begin to feel desperate and helpless, trapped by your circumstances with no obvious escape.

Flashbacks

That might explain that people with less specific recall only develop depression when they face long-term stresses, such as ongoing quarrels with their partner; those with fewer hassles show few ill-effects.

As well as depression, over-general memories could make people more vulnerable to post-traumatic stress disorder. It may seem counter-intuitive, because PTSD involves vivid memories of a traumatic incident. But these flashbacks appear to be the exception rather than the rule as people with PTSD tend to have trouble recalling other events from their past. Once again, these difficulties seem to be present long before the onset of the disorder 鈥� are often the first to develop the symptoms of PTSD, for instance. Perhaps a poor memory just weakens our mental fortress 鈥� and when the defences are down, it鈥檚 easier for anxiety, fear and painful flashbacks to intrude into our thoughts.

鈥淧oor memory weakens our mental fortress, allowing fear to intrude into our thoughts鈥�

Why do people lose access to their recollections in the first place? Given the complexity of the human mind, it鈥檚 probably the outcome of many interlinked processes. Williams thinks we may learn the over-general style of thinking from our parents, if they tend to talk in broad terms about the past. It could also begin as a coping mechanism, helping people to retreat from the pain of a difficult experience.

in Norway of Bosnian teenagers who had been young children during the Bosnian war in the 1990s. 鈥淭hey had seen people being killed, villages burnt down. They were kept in a state of terror for years,鈥� says Brennen. The teens found it harder to remember specific events in their past than their Norwegian peers.

By the time Brennen met the Bosnians in the late 2000s, many were living a relatively peaceful life and hadn鈥檛 yet developed signs of mental illness as a result of their experiences, over-general memories or otherwise. That doesn鈥檛 necessarily contradict the theory. As Anderson has found, the weaknesses in our defences only show during times of stress. Brennen suspects that the consequences might kick in once they face the challenges of adult life.

Although this theory of depression is gaining converts among researchers, it still has plenty of critics. in the UK points to a contradictory study showing that depressed people simply take longer to access their recollections. If you give them enough time, they can usually summon specific incidences for a cue word, he says. Perhaps they are just less keen than other people on sharing personal recollections with a stranger. 鈥淚 don鈥檛 think their memory has fundamentally changed,鈥� he says.

While the theory鈥檚 merits are still being debated, its proponents are already exploring whether a kind of memory training can be used to improve people鈥檚 recall and so reduce their symptoms of depression. , UK, for instance, has investigated a technique called Memory Specificity Training (MeST), which encourages people to practise delving into their memories. In effect, they are asked to repeat a similar version of 奥颈濒濒颈补尘蝉鈥檚 memory test over and over again, recalling detailed specific incidents for different cue words. Crucially, the events need not have anything to do with the person鈥檚 current anxieties. People can be taught MeST in groups and may only need five weekly sessions to see improvement if early results are anything to go by.

One of the first trials took place in Iran, carried out by Hamid Neshat-Doost at the University of Isfahan, who worked with Dalgleish in Cambridge before returning to his home country. It involved 23 depressed Afghani refugees, living in a community with little access to cognitive behavioural therapists. The 11 people who received five group sessions of MeST improved significantly, unlike the others, who went untreated. Importantly, those with the most improvements in their ability to recall specifics reported the greatest improvements in their mood.

Admittedly that was a small, unblinded trial and memory training would have to be compared with traditional talking therapies in a head-to-head trial before any conclusions could even begin to be drawn about their relative merits. After all, cognitive behavioural therapy is also becoming more widely and cheaply available through online programmes and group therapy. But Williams, who has worked on a similar form of memory training, says MeST could be another useful option for those who don鈥檛 respond well to cognitive behavioural therapy or antidepressants. 鈥淲hat鈥檚 nice is that it brings the patient on board in a collaborative way,鈥� he says. 鈥淚t isn鈥檛 stigmatising.鈥�

Sumner agrees that memory training looks promising, having tried to encourage her own patients to reminisce more specifically, with positive results. 鈥淭hey don鈥檛 see their past and future as [uniformly] negative,鈥� she says. 鈥淚t gives them something to latch on to, motivating them to make changes.鈥�