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Mental Illness: It's Not in Your Genes
Many neuropsychiatric ailments that are assumed to have a major genetic component don't seem to have one.
Even before the Human Genome Project wrapped up in April 2003, scientists have worked overtime to find the gene or genes responsible for autism, schizophrenia, Alzheimer's, ADHD, alcoholism, depression, and other ailments "known" to have major genetic components.
The problem is, many neuropsychiatric ailments that are assumed to have a major genetic component don't seem to have one.
More than a decade after the sequencing of the human genome, there is still no reliable genetic test for autism, Alzheimer's, schizophrenia, or any other major neuropsychiatric disorder (except for Huntingon's disease, for which there was already a test, prior to the Human Genome Project). In late 2012, scientists claimed (in a paper in Molecular Psychiatry) that a genetic test for autism had been devised. In actuality, the "test," a classifier developed using data from 237 single-nucleotide polymorphisms in 146 genes, proved unreliable. The software had been trained on one set of human genes (from central Utah) and tested against another set (from northern Europe); it correctly predicted if you were of northern European descent, not whether you might be at risk for autism.
Over 1,000 genes are known to be differentially expressed in the autistic brain, but as of yet there is no way to predict in advance who will differentially express the genes in question.
Meanwhile, more than 80 candidate genes for alcoholism have been identified—in the fruit fly. Likewise, hundreds of genes have been "implicated" in schizophrenia (the database at www.szgene.org currently contains 8,788 polymorphisms pertaining to 1,008 genes). But we are no closer to having reliable genetic markers for schizophrenia (much less depression) than we were in the 1930s, when the "feeble minded" were compulsorily sterilized (not just in Nazi Germany but in the U.S. and most western countries) to keep their inferior genes from propagating.
The problem is, there's no convincing evidence that schizophrenia (much less depression, or even alcoholism) is genetic in origin. To be sure, many neuropsychiatric problems (including schizophrenia) are familial, and most people blindly equate "runs in the family" with genetics. But the fact is, wealth, poverty, child abuse, eating/drinking habits, and many other things "run in families," yet no one seriously suggests high net worth (for example) is genetic.
The ultimade proof, supposedly, of the genetic basis of schizophrenia comes in the form of twin studies that have been done showing a high rate of concordance for schizophrenia in monozygotic (identical) twins versus fraternal (non-identical or dizygotic) twins. But as psychologist Jay Joseph points out in The Gene Illusion: Genetic Research in Psychiatry and Psychology Under the Microscope (2003, PCCS Books), the twin-study data are not particularly convincing when held up to scrutiny. Although early twin studies by Franz Kallman found concordance rates as high as 69% (which Kallman changed to 86% after applying unwarranted "age correction factors"), later studies have found much lower rates, and in fact the later the study, the lower the rate. By the late 1980s, some studies were reporting pairwise concordance rates of under 20% for schizophrenia in twins. The largest such study found:
Pairwise concordance rates for schizophrenia (11.0% for MZ and 1.8% for DZ) indicated environmental influence with apparent genetic liability.
Why shouldn't we believe the earlier twin studies? Aside from small sample size (thus low statistical power) there are substantial issues around lack of blinding, uneven diagnostic capability (not just regarding schizophrenia, but monozygosity of twins), and researcher bias. (Kallman was an avowed eugenecist.) But a more serious issue, according to Jay Joseph and other critics of twin studies, is that the "equal environment assumption" that underlies all such studies simply isn't valid. The equal-environment assumption says that identical twins are not exposed to an environment that's significantly different than the one fraternal twins are exposed to. (If there are environmental differences, then those differences, rather than genetic differences, might explain any difference in outcome between identical and fraternal twins.) A wide range of evidence casts doubt on the equal environment assumption. Indeed, whenever identical twins are given special treatment by parents (or teachers, total strangers, each other, etc.) based on similar appearance, the equal-environment assumption goes out the window. Joseph believes environmental confounds undermine every twin study, and on this basis alone, he condemns such studies as fundamentally unreliable.
Whether or not Joseph is right, the fact remains that scientists have failed miserably to find genes for schizophrenia, depression, and other major mental disorders. The most recent failure was reported in the April 2013 edition of Biological Psychiatry, wherein Karin Hek and 85 (yes, 85) coauthors tell of performing a genome-wide association study involving 34,549 individuals suffering from depression. Only one single nucleotide polymorphism (SNP) was "suggestive" of an association with depression, and that SNP didn't map to a known gene. With a certain degree of resignation, the authors concluded:
The results suggest that only a large sample comprising more than 50,000 subjects may be sufficiently powered to detect genes for depressive symptoms.
And yet the Hek writeup begins with: "Depression is a heritable trait that exists on a continuum of varying severity and duration." Which is exactly what the study did not show.
The truth is much harder to report. There is, as yet, no known gene for anything psychiatric. And the indications are that none will be found.
A new paper reveals that the Voyager 1 spacecraft detected a constant hum coming from outside our Solar System.
- Voyager 1, humankind's most distant space probe, detected an unusual "hum" in the data from interstellar space.
- The noise is likely produced by interstellar gas.
- Further investigation may reveal the hum's exact origins.
Voyager 1, humanity's most faraway spacecraft, has detected an unusual "hum" coming from outside our solar system. Fourteen billion miles away from Earth, the Voyager's instruments picked up a droning sound that may be caused by plasma (ionized gas) in the vast emptiness of interstellar space. Launched in 1977, the Voyager 1 space probe — along with its twin Voyager 2 — has been traveling farther and farther into space for over 44 years. It has now breached the edge of our solar system, exiting the heliosphere, the bubble-like region of space influenced by the sun. Now, the spacecraft is moving through the "interstellar medium," where it recorded the peculiar sound.
Stella Koch Ocker, a doctoral student in astronomy at Cornell University, discovered the sound in the data from the Voyager's Plasma Wave System (PWS), which measures electron density. Ocker called the drone coming from plasma shock waves "very faint and monotone," likely due to the narrow bandwidth of its frequency.
While they think the persistent background hum may be coming from interstellar gas, the researchers don't yet know what exactly is causing it. It might be produced by "thermally excited plasma oscillations and quasi-thermal noise."
The new paper from Ocker and her colleagues at Cornell University and the University of Iowa, published in Nature Astronomy, also proposes that this is not the last we'll hear of the strange noise. The scientists write that "the emission's persistence suggests that Voyager 1 may be able to continue tracking the interstellar plasma density in the absence of shock-generated plasma oscillation events."
Voyager Captures Sounds of Interstellar Space www.youtube.com
The researchers think the droning sound may hold clues to how interstellar space and the heliopause, which can be thought of as the solar's system border, may be affecting each other. When it first entered interstellar space, the PWS instrument reported disturbances in the gas caused by the sun. But in between such eruptions is where the researchers spotted the steady signature made by the near-vacuum.
Senior author James Cordes, a professor of astronomy at Cornell, compared the interstellar medium to "a quiet or gentle rain," adding that "in the case of a solar outburst, it's like detecting a lightning burst in a thunderstorm and then it's back to a gentle rain."
More data from Voyager over the next few years may hold crucial information to the origins of the hum. The findings are already remarkable considering the space probe is functioning on technology from the mid-1970s. The craft has about 70 kilobytes of computer memory. It also carries a Golden Record created by a committee chaired by the late Carl Sagan, who taught at Cornell University. The 12-inch gold-plated copper disk record is essentially a time capsule, meant to tell the story of Earthlings to extraterrestrials. It contains sounds and images that showcase the diversity of Earth's life and culture.
As the American population grows, fewer people will die of cancer.
- A new study projects that cancer deaths will decrease in relative and absolute terms by 2040.
- The biggest decrease will be among lung cancer deaths, which are predicted to fall by 50 percent.
- Cancer is like terrorism: we cannot eliminate it entirely, but we can minimize its influence.
As the #2 leading cause of death, cancer takes the lives of about 600,000 Americans each year. In comparison, heart disease (#1) claims more than 650,000 lives, while accidents (#3) take about 175,000 lives. (In 2020 and likely 2021, COVID will claim the #3 spot.)
Headlines are usually full of terrible news about cancer. Seemingly, you can't get away from anything that causes it. RealClearScience made a list of all the things blamed for cancer — antiperspirants, salty soup, eggs, corn, Pringles, bras, burnt toast, and even Facebook made the list.
The reality, however, is much more optimistic. We're slowly but surely winning the war on cancer.
Winning the war on cancer
How can we make such a brazen statement? A new paper published in the journal JAMA Network Open tracks trends in cancer incidence and deaths and makes projections to the year 2040. The authors predict that around 568,000 Americans will have died of cancer in 2020, but they project that number to fall to 410,000 by 2040. That's a drop of nearly 28 percent, despite the U.S. population being projected to grow from roughly 333 million today to 374 million in 2040, an increase of 12 percent. That means cancer deaths will decrease in both relative and absolute terms.
What accounts for this unexpected good news? The lion's share is the number of deaths attributable to lung cancer, which is projected to decrease by more than 50 percent, from 130,000 to 63,000. This drop is largely due to the decreasing use of tobacco products. Other deaths predicted to decline include those from colorectal, breast, prostate, and ovarian cancers, among others, such as leukemia and non-Hodgkin lymphoma (NHL).
The authors credit screening and biomedical advances for saving many of these lives. For instance, lead author Dr. Lola Rahib wrote in an email to Big Think that "colonoscopies remove precancerous polyps." She also noted that targeted therapies and immunotherapies have helped reduce the number of deaths from leukemia and NHL.
We'll never cure cancer
Now the bad news: We'll never cure cancer. There are at least three reasons for this. The first is obvious: We all die. The lifetime prevalence of death is 100 percent. The truth is that we are running out of things to die from. After a long enough period of time, something gives out — often your cardiovascular system or nervous system. Or you develop you cancer.
The second reason is that we are multicellular organisms and, hence, we are susceptible to cancer. (Contrary to popular myth, sharks get cancer, too.) The cells of multicellular organisms face an existential dilemma: they can either get old and stop dividing (a process called senescence) or become immortal but cancerous. For this reason, the problem of cancer may not have a solution.
Finally, there isn't really such a thing as a disease called "cancer." What we call cancer is actually a collection of several different diseases, some of which are preventable (like cervical cancer with the HPV vaccine) or curable (like prostate cancer). Unfortunately, some cancers probably never will be curable, not least because cancers can mutate and develop resistance to the drugs we use to treat them.
But the overall optimism still stands: We are slowly and incrementally winning the war on cancer. Like terrorism, it's not a foe that we can completely vanquish, but it is one whose influence we can minimize in our lives.
China has reached a new record for nuclear fusion at 120 million degrees Celsius.
This article was originally published on our sister site, Freethink.
China wants to build a mini-star on Earth and house it in a reactor. Many teams across the globe have this same bold goal --- which would create unlimited clean energy via nuclear fusion.
But according to Chinese state media, New Atlas reports, the team at the Experimental Advanced Superconducting Tokamak (EAST) has set a new world record: temperatures of 120 million degrees Celsius for 101 seconds.
Yeah, that's hot. So what? Nuclear fusion reactions require an insane amount of heat and pressure --- a temperature environment similar to the sun, which is approximately 150 million degrees C.
If scientists can essentially build a sun on Earth, they can create endless energy by mimicking how the sun does it.
If scientists can essentially build a sun on Earth, they can create endless energy by mimicking how the sun does it. In nuclear fusion, the extreme heat and pressure create a plasma. Then, within that plasma, two or more hydrogen nuclei crash together, merge into a heavier atom, and release a ton of energy in the process.
Nuclear fusion milestones: The team at EAST built a giant metal torus (similar in shape to a giant donut) with a series of magnetic coils. The coils hold hot plasma where the reactions occur. They've reached many milestones along the way.
According to New Atlas, in 2016, the scientists at EAST could heat hydrogen plasma to roughly 50 million degrees C for 102 seconds. Two years later, they reached 100 million degrees for 10 seconds.
The temperatures are impressive, but the short reaction times, and lack of pressure are another obstacle. Fusion is simple for the sun, because stars are massive and gravity provides even pressure all over the surface. The pressure squeezes hydrogen gas in the sun's core so immensely that several nuclei combine to form one atom, releasing energy.
But on Earth, we have to supply all of the pressure to keep the reaction going, and it has to be perfectly even. It's hard to do this for any length of time, and it uses a ton of energy. So the reactions usually fizzle out in minutes or seconds.
Still, the latest record of 120 million degrees and 101 seconds is one more step toward sustaining longer and hotter reactions.
Why does this matter? No one denies that humankind needs a clean, unlimited source of energy.
We all recognize that oil and gas are limited resources. But even wind and solar power --- renewable energies --- are fundamentally limited. They are dependent upon a breezy day or a cloudless sky, which we can't always count on.
Nuclear fusion is clean, safe, and environmentally sustainable --- its fuel is a nearly limitless resource since it is simply hydrogen (which can be easily made from water).
With each new milestone, we are creeping closer and closer to a breakthrough for unlimited, clean energy.