Every country in the world is facing and failing to tackle a mental health crisis, from epidemics of anxiety and depression to conditions caused by violence and trauma, according to a review by experts that estimates the rising cost will hit $16tn (£12tn) by 2030.

A team of 28 global experts assembled by the Lancet medical journal says there is a “collective failure to respond to this global health crisis” which “results in monumental loss of human capabilities and avoidable suffering.”

The burden of mental ill-health is rising everywhere, says the Lancet Commission, in spite of advances in the understanding of the causes and options for treatment. “The quality of mental health services is routinely worse than the quality of those for physical health,” says their report, launched at a global ministerial mental health summit in London.

When it comes to mental health, says the commission, every country is a developing country. “Government investment and development assistance for mental health remain pitifully small,” says the report. The high cost of $16tn by 2030 is estimated from previous World Bank data on the loss to the global economy of people of working age with mental health problems.

In some countries, people with mental disorders are abused and incarcerated, it says. “Human rights violations and abuses persist in many countries, with large numbers of people locked away in mental institutions or prisons, or living on the streets, often without legal protection,” it says.

Prof Vikram Patel of the Harvard Medical School, joint lead editor, said mental ill-health caused “colossal human suffering” and was responsible for substantial numbers of deaths that are attributed to other causes. “Mental health problems kill more young people than any other cause around the world,” he said.

Tens of thousands of people with mental disorders are chained in their own homes Prof Vikram Patel, Harvard Medical School

Suicides are attributed to deaths from injuries. Opioid deaths are considered to be drug misuse. “We are treating mental illness as a risk factor,” said Patel. “A lot of global health priority setting has historically been around diseases that kill.” The commission estimates that 13.5 million deaths every year could be averted if the underlying mental ill-health problems were addressed.

In many countries there is no expectation of help. Surveys in India and China, which have a third of the global population, suggest that more than 80% of people with any mental health or substance use disorder did not seek treatment. And when they do seek help, the quality is poor.

Human rights violations occur most often against people with learning disabilities and those with mental health disorders such as schizophrenia. “Tens of thousands of people with mental disorders are chained in their own homes, or in prayer camps and traditional healing facilities,” says the report.

When people are freed, it may be without warning or proper preparation for their care, leading sometimes to arrest, imprisonment and early death. “In 2016, a tragic case occurred in South Africa when the Gauteng Department of Health stopped funding a large 2,000­ bed facility and allowed the dis­charge of vulnerable people with psychosocial disability into improperly licensed community residential facilities, leading to the death of more than 140 people,” says the report.

The commission recommends a much higher priority for mental health and parity with physical healthcare, as well as the integration of mental health care into routine primary care.

• This article was amended on 11 October 2018 because an earlier version wrongly implied that a learning disability was a mental illness. This has been clarified.

• In the UK, Samaritans can be contacted on 116 123 or email jo@samaritans.org. In the US, the National Suicide Prevention Lifeline is 1-800-273-8255. In Australia, the crisis support service Lifeline is 13 11 14. Other international suicide helplines can be found at www.befrienders.org.