Depression can have a profound impact on a person’s life, work, and relationships. But a new study shows the true toll of mental health conditions on a global scale.

New research led by Alize Ferrari from the University of Queensland and the Queensland Centre for Mental Health Research in Australia found that depression is the second leading cause of the global disability burden.

Depression, defined as a persistent state of sadness or disinterest in things once found pleasurable, is one of the most common mental disorders.

The World Health Organization states that approximately 350 million people worldwide have depression, or about four percent of the world’s population.

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Rob Dobrenski, a psychologist in New York City and author of Crazy: Notes On and Off the Couch, said more than half of his practice centers around depression.

“While many people have chronic depression that ultimately leads to a disability, it's common for it to become debilitating immediately. It's not necessarily something that builds and becomes worse over time,” Dobrenski, who was not involved in the study, said. “Unfortunately, the system moves very slowly so it can take a long time for someone to become qualified [for mental health care], even though they are ‘eligible’ within days.”

However, he added, some types of depression can fade away just as quickly, so it's sometimes a disservice to designate someone as disabled so quickly.

Depression Around the World

The new study, appearing in the journal PLOS Medicine, shows that rates of major depressive disorder (MDD) vary by country and region, but are highest in Central America and Central and Southeast Asia.

Afghanistan, which has seen political turmoil and war since long before the U.S. occupation began 2001, leads the world in rates of depression, the researchers discovered. Japan, on the other hand, has the lowest rate of depression disability worldwide.

To reach their conclusions, researchers scoured published studies on MDD, or clinical depression, and dysthymia, which is a milder form of depression. They assessed the diseases’ impact on the number of years people lived with disability, and substituted “reasonable estimates” for poorer countries on which few studies have been published.

While the numbers showed that major depression ranked high among the causes of global disability in 2010, depression also contributes to deaths from other conditions, especially suicide and heart disease.

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In the U.S., depression is considered a psychiatric disability and is covered under the Americans With Disabilities Act.

The Queensland researchers say their results “not only highlight the fact that depressive disorders are a global health priority, but also that it is important to understand variations in burden by disorder, country, region, age, sex, and year when setting global health objectives.”

It appears that no one is immune to depression. While it most often affects women, men can also get depression, and symptoms in children can appear when they are as young as three years old.

A major hurdle in battling depression worldwide is that it rarely travels alone.

“It can be a stand alone condition or easily mixed with other mental or physical issues,” Dobrenski said. “Depression and anxiety are often paired together, and depression and pain issues are also common.”

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Getting Help for Depression

The cause of depression is still unknown, but most current research points to a chemical imbalance in the brain, making it a physical disease that someone cannot simply “snap out of.”

Though there is no cure, depression is a highly treatable disease. Therapy with a mental health professional, medications, and lifestyle changes, including a healthy diet and exercise, have all been shown to successfully improve the quality of life for someone with depression.

“Depression is a treatable condition that I recommend be treated quickly,” Dobrenski said. “Very mild depression can often resolve with cardiovascular exercise and a good support system. Failing that, seeking out a therapist and possibly medication is a smart move, as both of these have a good track record for depression.”

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