Mental health stigma is a key factor preventing people from accessing the care they need, according to new research from King's College London.

The new study, published in Psychological Medicine, brings together data from 144 studies, including over 90,000 participants worldwide.

Approximately 1 in 4 people have a mental health problem, yet in Europe and the US, up to 75 percent of people with mental health disorders do not receive treatment. For many disorders such as psychosis, bipolar disorder, major depression and anxiety disorders, delaying or avoiding care is associated with worse outcomes.

Professor Graham Thornicroft, from the Institute of Psychiatry (IoP) at King's College London and senior author of the paper, says: "We now have clear evidence that stigma has a toxic effect by preventing people seeking help for mental health problems. The profound reluctance to be "a mental health patient" means people will put off seeing a doctor for months, years, or even at all, which in turn delays their recovery."

The study, which was funded by the National Institute for Health Research (NIHR) as a part of the SAPPHIRE Programme, looked at the effect of stigma on how individuals with mental health problems accessed and engaged with formal services, including GPs, specialist mental health services and talking therapies.

Stigma was the fourth highest ranked barrier out of ten. The main types of stigma preventing people from accessing care were 'treatment stigma' (the stigma associated with using mental health services or receiving mental health treatment) and 'internalised stigma' (shame, embarrassment). Other important barriers preventing people seeking help were fear of disclosing a mental health condition; concerns about confidentiality; wanting to handle the problem on one's own; and not believing they needed help.

The study also identified certain groups for whom stigma had an even stronger effect on preventing people seeking help. These included young people, men, people from minority ethnic groups, those in the military and health professions.

Dr Sarah Clement, from the IoP at King's and lead author of the paper, says: "Our study clearly demonstrates that mental health stigma plays an important role in preventing people from accessing treatment. We found that the fear of disclosing a mental health condition was a particularly common barrier. Supporting people to talk about their mental health problems, for example through anti-stigma campaigns, may mean they are more likely to seek help."