WELLINGTON: What are seen as three sep­ar­ate men­tal health con­di­tions – depres­sion, anxi­ety and post-trau­matic stress dis­order (PTSD) – could really be dif­fer­ent aspects of the same under­ly­ing brain dis­order.

In fact, the 14 most com­mon men­tal health and neurodi­versity con­di­tions seem to be five clusters of closely related dis­orders.

The find­ings, which come from the largest genetic study of men­tal health and neurodi­versity, sug­gest the way we define and treat men­tal health may be flawed.

And they could explain why many people are dia­gnosed with more than one con­di­tion – because they have the same genetic root causes.

“That these things go together so often is not just something to be observed, but a prob­lem to be solved,” said Dr Andrew Grotzinger, of the Uni­versity of Col­or­ado Boulder, US, who was involved in the research. “This work helps move the needle in terms of help­ing to solve that prob­lem.”

The research, pub­lished in the journal Nature, is the out­come of a world­wide effort to under­stand the genet­ics of numer­ous men­tal health con­di­tions, as well as aut­ism and ADHD which come under the psy­chi­atry umbrella within health ser­vices although they are classed as neurodevel­op­mental con­di­tions.

It is by no means the first time our under­stand­ing of men­tal health prob­lems has been ques­tioned.

Most psy­chi­at­rists would acknow­ledge our dia­gnosis and treat­ment of these con­di­tions is at a far earlier stage than for most phys­ical health prob­lems, and is on a less sci­entific foot­ing.

We still do not know the under­ly­ing bio­lo­gical causes of the most com­mon con­di­tions such as depres­sion, anxi­ety, anor­exia and schizo­phrenia.

With men­tal health prob­lems, there are no blood tests or scans to con­firm dia­gnoses. What’s more, treat­ments help some people but not all. At best, they tend to alle­vi­ate rather than cure.

Hope­fully we are going to be able to find the levers to pull that are going to treat all of them bet­ter under­stand the root causes of men­tal ill­ness.

The work was done by an enorm­ous inter­na­tional group of sci­ent­ists who shared the genetic sequences of more than one mil­lion people with 14 men­tal health or neurodi­versity con­di­tions, as well as five mil­lion unaf­fected people who were used for com­par­ison.

Con­firm­ing pre­vi­ous find­ings, the con­di­tions were found to have strong genetic influ­ences, involving 238 com­mon genetic vari­ants.