Common Genetic Ground Found for Depression, Schizophrenia, Autism

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New research bolsters the idea that the risk for psychiatric and developmental disorders isn’t specific to particular conditions — and that could mean new opportunities to treat mental illnesses that focus more on their common genetic roots.

Mental illnesses like depression and schizophrenia clearly run in families, but neuroscientists have always assumed that the biological drivers behind these disorders were distinct. However, expanding on results reported earlier this year from psychiatry’s largest ever experiment, researchers now report that known genetic variations account for 17% to 29% of the risk for schizophrenia, depression, bipolar disorder, autism and attention-deficit/hyperactivity disorder (ADHD). And risk for one condition is often strongly linked with risk for others.

Published in Nature Genetics, the study was funded by the National Institute on Mental Health (NIMH) and involved collaboration between nearly 400 scientists in 20 countries working with genetic data from some 59,000 people.

(MORE: Most Common Psychiatric Disorders Share Genetic Roots)

Studying gene-based differences among the patients and in people who did not have mental illnesses, the scientists detailed with unprecedented precision how groups of the same genetic mutations could be linked to different mental illnesses. Bipolar disorder and schizophrenia were most highly correlated — a finding that jibes with both earlier research and the fact that the conditions can sometimes be mistaken for each other in the clinic. The latest data suggests that seemingly disparate symptoms — patients with bipolar experience extreme mood swings, while people with schizophrenia often suffer from delusions and paranoia — may not necessarily derive from different genes, but rather from different timing of exposures to risk factors, such as toxins or infectious disease during pregnancy, or early life trauma.

“It has long been hypothesized that psychiatric disorder diagnoses are superimposed onto an underlying spectrum,” says lead author Naomi Wray, associate professor of statistical and psychiatric genetics at the University of Queensland in Australia, referring to the idea that the same genes can produce different symptoms in different circumstances. “Our results provide direct empirical support for this.”

“We thought these were completely distinct diseases,” says Bruce Cuthbert, director of the division of adult translational research and treatment development at NIMH, explaining that the idea of a distinction between bipolar and schizophrenia has been a core part of psychiatry for over a century. But now, he says, “We’re gradually seeing that these are, in fact, highly related conditions and only appear different from the surface symptoms.”

(MORE: When Meditation Helps Mental Illness — and When It Hinders)

Some of the connections were less obvious. While bipolar and schizophrenia were the most strongly linked, and bipolar and depression were moderately linked (not surprisingly), the association between depression and schizophrenia was almost as strong as that between bipolar and unipolar depression. Prior studies had suggested the possibility that these conditions tended to occur in families, but since living with a severely mentally ill relative can be stressful and contribute to depression, it seemed more likely that such environmental reasons explained the connection rather than any inherited mutations.

The new results offer support for a new approach to diagnosis that NIMH’s director Dr. Thomas Insel announced in May. Noting that the current system hasn’t been particularly fruitful in generating new treatments, Insel said the agency would be moving away from funding research projects based on Diagnostic and Statistical Manual of Mental Disorders (DSM) categories, which classify disorders simply by noting clusters of symptoms. This often results in people carrying multiple diagnoses, since, for example, obsessive focus can be a symptom of both autism and obsessive-compulsive disorder and a lack of pleasureful emotions can be a symptom of depression, bipolar disorder or schizophrenia.

(MORE: Viewpoint: My Case Shows What’s Right — and Wrong — With Psychiatric Diagnoses)

Instead, the new Research Domain Criteria systems will look for the genetic roots of individual symptoms. That should reduce multiple diagnoses and improve genetic research by narrowing it down to specific problems with particular brain systems. And that could open up new ways of thinking about and treating mental disorders that may seem disparate in the clinic but actually share biological roots. If Grandma’s schizophrenia and Uncle John’s depression are caused by the same combination of genes affecting the brain’s motivational systems, it may be possible to target this system early to prevent John Jr. from ever becoming ill.

When the latest version of the manual, DSM-5, was issued in May, Insel told TIME, “We know that the DSM approach is not the way to understand these disorders. It may be a way to bill for them, but it’s not a way to develop science or even identify who should get what treatment.” The latest genetic findings suggest he may be right, and if mental disorders share more in common than previously thought, that could mean that more people might benefit from more targeted use of existing treatments as well, which is good news for those affected by some of the most devastating disorders in medicine.

MORE: DSM-5 Debate: Committee Backs Off Some Changes, Reopens Comments

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WindyCravalho
WindyCravalho

Transcranial Magnetic Stimulation (TMS) is a noninvasive treatment that was approved in 2008 and is used to treat depression. I work with patients everyday that suffer from depression and have seen some impressive results. Rather than explaining on here, I'll give you a link to visit. www.neurostar.comYou can also visit the Dr. Oz site by searching "TMS" or on YouTube by searching "Dr. Oz TMS" and you will find a part 1 and part 2. He does very well explaining the treatment. ;)

RekkaRiley
RekkaRiley

There's also growing evidence that many of these disorders stem from things the brain and body are technically supposed to be doing, and some of them may have had a major evolutionary advantage at some point in our history.

AD/HD was the first case of this.  Many of the symptoms that we see as negative in our post-industrial environment were actually major advantages in a hunter-gatherer society.  What we see as "not paying attention and easily distracted" on the negative face of the coin comes out as "constantly scanning environment for food" on the positive side.  People with AD/HD have a much stronger "prey drive" than neurotypical people; they constantly scan their environment, throw themselves into the chase at a moments notice (hyperfocus, goal-oriented), they're impulsive (if you startle a rabbit out of its burrow, but you were hoping for a deer, you really can't afford to waste time debating whether you should catch the rabbit anyway, you just do it), and they have a need to be constantly moving around (if you have to forage or hunt for food, staying still means going hungry).  

People with AD/HD often excel at sports or in the military, or in any occupation that has very clear goals but allows some creativity in how to reach that goal, because those occupations allow them to channel those instincts in a constructive way.  I know several parents of ADHD children who discovered that placing their child in an after school sport of some sort mitigated the need for medication.  Especially if there were practices before classes started, because then the kids could run off all that extra energy and be calm enough to concentrate.  

I think it's important to note that rates of AD/HD started jumping right around the time that schools started cancelling recess or severely restricting children from engaging in running around or roughhousing during free time.  Without an outlet for that extra energy, children start acting out and getting restless.

Dr. Thom Hartmann had an excellent book on this, called "ADD: A Different Perspective."

There's been a similar discovery with Depression.  Scientists now believe that depression is caused when your brain recognizes some sort of problem and tries to reroute every last bit of processing power it has towards solving that problem...at the expense of everything else. 

Problem is...this is a subconcious process, meaning the patient might not be able to pinpoint the problem on their own.  They keep fixated on every little negative detail as their brain tries to figure out a solution to the problem.  The current theory on what makes Clinical Depression different from normal bouts of depression is that the trigger is either too sensitive (meaning normal, everyday occurances are enough to trigger an episode), or the built-in fail-safe that keeps the brain from taking things too far is damaged, so it reroutes processing power away from areas that are critical for survival (resulting in self-harm and suicide).

They're having a lot of success with new therapies designed around removing the stigma of depression by explaining to patients that there actually isn't anything wrong with them, and focusing on pinpointing the exact problem that triggered that episode of depression and either helping the patient come up with solutions for fixing the problem (thus allowing the brain to relax and go back to business as normal), or at least tricking the brain into thinking the problem has been fixed.

Here's the original article from Scientific American Mind:  http://www.scientificamerican.com/article.cfm?id=depressions-evolutionary

For other disorders, just because we haven't found the reason for it yet, doesn't mean it doesn't exist.  Science marches on, always.

aliberaldoseofskepticism
aliberaldoseofskepticism

@RekkaRiley Bipolar also. Someone with bipolar will certainly be more creative. And since humans are superstitious because our intelligence makes us see connections that aren't there, what does that say about schizophrenia, a disease characterized by, wait for it, seeing connections that aren't there?