To date, several researchers have proven that physical activity can lower one’s risk of developing depression. While the World Health Organization (WHO) recommends people to exercise for at least two and a half hours every seven days, a team of scientists from the University of Cambridge has determined exactly how much exercise can help fight depression.

Publishing their findings in JAMA Psychiatry, a peer-reviewed medical journal published by the American Medical Association (AMA), the researchers compiled the results of 15 pre-existing studies which analysed the activity and health outcomes of 191,130 adults—including 28,000 who had depression—measured over a median of eight and a half years.

Here, incidents of depression were determined with an official diagnosis or an analysis of prevailing symptoms, as recorded by the researchers who completed the original studies. Exercise was additionally measured using a unit called the metabolic equivalent of task (MET). A MET minute is essentially the energy expended while performing any activity for one minute, expressed as a ratio compared to the energy expended while at rest. For instance, cycling makes up 7.5 MET minutes while salsa dancing and playing the guitar (while standing) are 4.5 and 3 MET minutes respectively.

Now, for healthy adults under the age of 65, the WHO recommends 600 MET minutes—or 10 MET hours—a week. The team of researchers in question, however, found that a reduced risk of depression starts to kick in at about half of the WHO’s recommended minimum for weekly physical activity. Around 75 minutes, to be exact.

Compared to adults with zero to no physical activity, those who accumulated 4.4 marginal MET hours per week had an 18 per cent lowered risk of developing depression. These numbers hit 25 per cent in people who accumulated the 8.8 marginal MET hours (almost as much as the WHO recommendation) per week. What’s more, is that these benefits do not increase much after you reach the suggested level of activity. CrossFit, who?

“Substantial mental health benefits can be achieved at physical activity levels even below the public health recommendations,” the researchers noted in this regard. “[There was] an additional benefit for meeting the minimum target, but limited extra benefit beyond that.”

The team further highlighted the key factors behind exercise of such little frequency or intensity translating into positive ingredients for our mental health. For starters, exercise stimulates the release of endorphins—also known as the feel-good chemicals—which helps lift our mood. It is also proven to increase the size of one’s anterior hippocampus, thereby improving spatial memory and nerve connections to help relieve mental concerns. Frequent workouts can additionally push one’s self-perception in a positive light and help initiate social interactions at the gym or local club. People also exercise in green spaces quite frequently, another depression fighter on the list.

The study further went on to note how depression is the leading cause of mental health-related disease, affecting around 280 million people worldwide. It is also associated with increased mortality rates—triggered by a variety of conditions. But while those with regular exercise routines are less likely to suffer from depression, a part of this claim can be traced to reverse causation: people without depression are more likely to have the mindset needed to work out. However, scientists believe exercise has a protective effect on one’s brain. “Assuming causality, one in nine cases of depression might have been prevented if everybody in the population was active at the level of current health recommendations,” they added.

As 82.1 million US residents aged six and above admit to not having exercised at all in their lifetime, the team of researchers believe this minimum level of activity might just encourage a small portion of them to strap on their running shoes and take a brisk walk around their neighbourhood.

Last month, The Lancet Regional Health – Americas published a study examining the effects of the COVID-19 pandemic on our mental health. Polling participants both at the very beginning of the pandemic and a year later, the researchers concluded that depression rates have more than tripled in the US. Not only has the pandemic aided a spike in mental health concerns, but the findings proved that the increase is actually worse than other large-scale traumatic events like catastrophic weather or terror attacks.

At a time when mental health conditions like depression remain stigmatised across cultures—with people often spending years just to land crucial appointments for diagnosis and treatments—scientists at the Indiana University School of Medicine have developed a coveted tool, claimed to be psychiatry’s “first-ever biological answer to diagnosing a mood disorder.”

The study, as noted by Al Jazeera, delves into the biological basis of mental health concerns by developing a blood test using ribonucleic acid (RNA) markers that help distinguish the type of condition a person has. Drawing on 15 years of previous research into how psychiatry relates to blood gene expression biomarkers, the team—led by Doctor Alexander Niculescu—has proved that it’s possible to diagnose depression and bipolar disorder with a blood test. The blood test has clinical utility, is able to distinguish between the two conditions and can eventually match people to the right medications.

“This avoids years of trial and error, hospitalisations, and side-effects,” Doctor Niculescu told Al Jazeera. “As these are very common disorders, we think we can do a lot of good with this and other tests and apps we have developed.”

So how exactly can a blood test diagnose a mental health concern? This essentially loops back to the systems in our body—including the brain, the nervous system and the immune system—which have a common developmental route. “For example, when you’re stressed or depressed, there are psycho-neurological mechanisms, hormones and other things that are released that affect your blood and your immune system,” Doctor Niculescu explained, adding how an immune activation or inflammation would therefore affect the brain.

In the first stage of the study, the group of scientists identified a list of RNA biomarkers that could track one’s mood over a period of time. After validating the list among subjects with clinically severe depression and mania, they finalised 26 biomarkers—which they narrowed down to 12 with further testing. “With these findings, doctors would be able to send patients to a lab for bloodwork to indicate the causes of their symptoms, just as they would for a physical illness,” Doctor Niculescu said.

The biomarkers could additionally help with treatment, given how some of them were found to be affected by Selective Serotonin Reuptake Inhibitors (SSRIs), a class of antidepressants. Three other biomarkers were identified in previous work to be affected by lithium carbonate—a mood stabiliser used in the treatment of bipolar disorder. “Depending on which of those biomarkers are changed in [a patient], we have a list of medications… ranked by how tightly they match [the patient’s] biological profile,” the expert continued.

The blood tests developed by Doctor Niculescu and his team are currently available as Clinical Laboratory Improvement Amendments (CLIA)—a set of US government standards for laboratories that test human specimens for health assessment or to diagnose, prevent, or treat disease—for physicians to order.

However, according to Professor Ian Hickie, co-director of health and policy at the University of Sydney’s Brain and Mind Centre, finding one single algorithm that applies to all people with mood disorders is unlikely—because the conditions are unique and based on clinical presentation at different stages of life. His teammates are instead in the pursuit of connecting physiology and biology to the personalised symptoms of individuals and not their broad categories of illness.

“What systems are actually perturbed? How are they represented? What are the markers of that that you can detect?” he explained. “And [then] what is the combination of biological, behavioural and other treatments that corrects the situation… and then keeps you well?” According to the professor, all of these findings can be coupled with clinical assessment for a more accurate and conclusive diagnosis and treatment.

Nevertheless, innovations like Doctor Niculescu’s blood test can undoubtedly transform early diagnosis of mental health concerns altogether. According to Doctor Sonia Kumar, a Sydney-based psychiatrist, such objective tests are a game changer especially for conditions like bipolar disorder which first manifests itself as depression with the full array of manic symptoms taking years to appear and evolve over the years. In other cases, these symptoms may exist but on a lower spectrum capable of bypassing existing diagnosis. “If there were a biological test that could clarify these variables along with clinical assessment, clinicians could start accurate treatment earlier—which could mitigate a lot of suffering before it even happens,” Doctor Kumar told Al Jazeera.

With the ‘you’re just sad, sleep it off’ stigma still attached to mental health conditions like depression, the study led by Doctor Niculescu harbours the potential of playing a significant part in the psychiatric toolkit for diagnostics. And as Kathmandu-based psychiatrist, Doctor Pawan Sharma, explained, such tests could break down barriers—particularly among those from more rural and isolated communities where there is lower cultural awareness about mood disorders.

“They come [to physicians] with physical symptoms—like headaches, insomnia, loss of energy, heart palpitations—and they [are then referred] to psychiatrists,” Doctor Sharma noted, adding that an objective test would give patients something tangible to help explain how they are feeling. This, in turn, makes such innovations a necessary step to reach a horizon where we don’t have to bank on scientific test results to ‘validate’ our mental health concerns.