Story highlights Anxiety and depression are two of the most common mental health disorders in the world

Treating such conditions could benefit global economies, new study says

(CNN) One moment she's dolled up, smiling effortlessly toward the camera. The next she's in bed, in tears, just trying to calm down.

When a panic attack strikes, Amber Smith's world stops. The Rugby, England, resident posted photos on Facebook last week to show how dramatic a panic attack can alter not only a person's emotional state, but their physical state as well.

"I've been battling with anxiety and depression for years and years and there's still people that make comments like, 'You'll get over it; you don't need tablets; just be happier; you're too young to suffer with that," Smith wrote in a post, which more than 16,000 people shared online.

Smith is one of the millions of people worldwide suffering from a mental health disorder. Between 1990 and 2013, the number of people suffering from depression or anxiety, two of the most common mental disorders, increased by nearly 50%, from 416 million to 615 million globally, according to the World Health Organization (WHO).

Although that figure is climbing, investing in treatment could lead to healthier people, and even healthier economies.

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