Latest estimates from the World Health Organization (WHO) revealed that more than 300 million people in the world are now living with depression, showing an 18 percent increase from 2005 to 2015.

The WHO's new estimates of people living with depression was released leading up to the celebration of World Health Day, which will serve as the high point for their year-long "Depression: let's talk" campaign.

"The continuing stigma associated with mental illness was the reason why we decided to name our campaign Depression: let's talk," said Dr. Shekhar Saxena, Director of the Department of Mental Health and Substance Abuse at the WHO, in a press release. "For someone living with depression, talking to a person they trust is often the first step towards treatment and recovery."

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According to the WHO, about 50 percent of people with depression do not get treatment. Often characterized by persistent sadness and loss of interest in previously enjoyable activities, depression is a mental health condition that could be treated by either taking therapy sessions, antidepressant medications or a combination of both. However, lack of support for people with mental health disorder, in addition to the fear of stigma, may be preventing patients from seeking help.

People living with depression could be at a higher risk of substance abuse and non-communicable diseases including diabetes and heart disease. Patients with diabetes and heart disease are also most likely to develop depression over time.

Depression is now considered as the leading cause of ill health and disability worldwide. It is also an important risk factor for suicide.

Aside from the crippling sadness, people living with depression may also experience loss of energy, change in appetite, anxiety, erratic sleeping behavior, reduced concentration, indecisiveness, restlessness, feelings of worthlessness, suicidal thoughts, guilt and hopelessness.

The WHO is urging all government leaders to boost up their country's investment that supports people with mental health disorders. They claim that every $1 investment for treating depression and anxiety could lead to a return of $4 in better health and productivity.

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