The quality of the air we breathe may be a trigger for so-called psychiatric problems, and the age we start breathing polluted air could also be a factor.

Although the therapies appeared to be effective at the time, most of the teenagers who were treated had relapsed within a few years. Just 22 per cent were still free of their anxiety or depression, researchers from Connecticut University's School of Medicine discovered.

They checked on the progress of 319 teenagers who had been treated for three months either with the SSRI antidepressant Lustral (sertraline) or CBT. Both are established and proven treatments for anxiety and depression, the researchers emphasised.

The drugs—and mainly the SSRI (selective serotonin reuptake inhibitor) antidepressants—lower "the emotional impact of negative events", say researchers from the University of Vienna.

Many of the body's organs, including the heart, kidneys, lungs and liver, depend on serotonin, a chemical that the drugs block to treat depression.

Advocates of the therapy, which is also known as earthing, claim it can help reduce stress, depression and anxiety, and help us manage pain better.

Aside from all the other health risks, processed foods also affect your ability to concentrate. And the effects can be even worse if you already suffer from a leaky gut.

The attacks have produced symptoms remarkably similar to the effects of pulsed radiofrequency and microwave electromagnetic (RF/MW) radiation, which are emitted by cell phones, wi-fi networks and microwave ovens, says one of the world's leading experts.

Studies that have deemed the devices to be safe are usually paid for by manufacturers, says Beatrice Golomb, professor of medicine at the University of California's San Diego School of Medicine.

But it's still to be established whether arginine supplements could help reverse depression, say researchers from the University of Eastern Finland.

Those who eat the most chocolate every day—and that is up to 450g, or a whole small bar—were also the least likely to suffer clinical depression, diagnosed by a health practitioner.

Depression, anxiety and PTSD (post-traumatic stress disorder) are not illnesses; instead they are natural responses to adversity, as suggested by the fact that one in five people in war-torn countries are depressed compared with just one in 14 in countries not in conflict.

It's yet another example that environment beats genes, say researchers from Massachusetts General Hospital. Just 35 minutes of any type of exercise—high-intensity, such as aerobic or dance, or low-intensity, such as yoga and stretching—every day reduces the risk of depression, or a further depressive episode, even in people with a genetic predisposition for the problem.

A leaky gut is just that: our intestinal barrier weakens and allows bacteria into the bloodstream. And people who have hostile and angry confrontations with their partner end up with more bacteria in their blood, suggesting the upset has made the gut leaky.

Researchers from the Ohio State University tested the theory on a group of 43 healthy married couples. They were asked to talk about a sensitive issue, such as money or the in-laws, and they were observed via a video camera. Blood samples were taken before and after the argument, and the couples whose arguments became the most heated were also the ones with the highest levels of bacteria in their blood. In fact, the ones who had the most hostile confrontations had 79 per cent more bacteria in their blood than those who had a more equitable discussion.

A high-fat diet changes the bacteria in the gut and makes you more likely to suffer from depression and anxiety as a result.

Researchers started investigating a possible link after noticing that obese people with type 2 diabetes were more likely to suffer from acute depression. While anyone can be depressed, the diabetic seems to feel it more keenly.

When laboratory mice are fed a high-fat diet, they become more erratic, and show signs of depression, anxiety and obsessive behaviour, say researchers from Harvard Medical School.

Although our brains are always renewing—in a process known as neurogenesis—the connections between neurons become less efficient as we age, and this could be the reason older people have cognitive problems such as memory loss.

It may be hard to believe that by taking a probiotic like kefir, you can alter the composition of your gut bacteria in a way that positively affects your mood and brain function, while also resolving your irritable bowel syndrome (IBS). But a massive wave of research into the brain-gut axis has shown exactly that.

Kefir—a fermented product similar to liquid yogurt—has been around for millennia, but today it's poised to become a major player in a new frontier in neuroscience because of its actions as a 'psychobiotic.' This is a new term for a combination of live organisms that, when ingested in adequate amounts, produce mental health benefits.

While it's been known for over a century that bacteria can have positive effects on our physical health, it's only in the last 10-15 years that studies have shown there's a connection between the gut, the bacteria in the gut and the brain.

More than 200 of the most commonly prescribed drugs—ranging from heart medications, painkillers, and indigestion pills—are linked to depression and suicidal ideation (thoughts) as side effects.

This means that one in three people are unwittingly taking a prescription drug that can cause these mental health problems, say researchers from the University of Illinois.

The risk could be greater still as many older people are taking more than one of the drugs at the same time. Depression has affected around 15 per cent of people who were taking three or more of the drugs, 9 per cent of those taking two drugs, and 7 per cent of those taking just one of the drugs.

Resveratrol blocks stress signals in the brain, and it could also help other neurological disorders such as depression and anxiety.

After five years, people who used cognitive behavioural therapy (CBT)—the 'talking therapy'—were coping as well as those who instead had opted to take antidepressants.