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Parkinson’s disease is a progressive motor disorder that causes tremors and stiffness and is often accompanied by dementia. In the small minority of cases, it’s hereditary -- it runs in families.

The rest of the time? We don’t really know what causes it, which means it’s hard to predict or treat. But in a recent study published in the journal Molecular Psychiatry, researchers have identified a gene that appears to be linked to those other cases, which are known as sporadic Parkinson’s disease.

And that’s a big step forward in understanding this disease. The researchers were interested in the idea that, even though this kind of Parkinson’s isn’t directly passed on from family member to family member, it could still have a genetic component. A certain gene could potentially be a kind of risk factor for sporadic Parkinson’s disease, predisposing someone to getting it under the right environmental circumstances.

So, the researchers took a look at several different genome-wide studies of people with Parkinson’s disease. They were on the lookout for sets of genes that had effects on the same group of cellular processes. See, we haven’t been able to spot any one gene that’s strongly associated with sporadic Parkinson’s.

And it’s not for lack of trying. But many genes can all affect the same process in a cell. So if you look at all of those genes together, you might turn up genes that don’t always cause Parkinson’s but that can definitely be a risk factor for it.

This approach pointed researchers towards type I interferon signaling, a process involved in sounding the alarm against infecting viruses and microbes. It seemed to be disrupted in many people with Parkinson’s. There were several troublesome genes, but one in particular, a gene called PIAS2, seemed to be especially involved in the process.

Tests in mice showed that increasing PIAS2 was enough to cause. Parkinson’s-like pathology and cognitive impairment. And reducing the expression of the gene improved the motor skills and cognitive performance of mice with Parkinson’s-like symptoms.

Why? Well, in addition to its role in the immune system, they found that PIAS2 also plays a role in everyone’s favorite organelle: the mitochondria, which provides energy for the cell. Too much PIAS2 kept damaged mitochondria from being disposed of.

They accumulated in the neurons instead, which could eventually lead to neuronal cell death, and, potentially, the symptoms of Parkinson’s. There’s still a lot to be done, but this provides a solid direction for future research. And it’s a pretty cool illustration of what can happen when you look at groups of risk factors, instead of just one.

For our next story today, it’s hurricane season in the Atlantic right now. And that’s increasingly bad news. Since the 1980s, the number of Category 3, 4, and 5 North Atlantic hurricanes has increased.

Now, meteorologists definitely believe that climate change is putting us at risk of more of these intense tropical cyclones. That is, the big dangerous storms that are often referred to as hurricanes or typhoons. But a paper published this week in the journal Nature Communications suggests the current increase in hurricanes in the North Atlantic ocean could be more tied to other types of human activity.

And the researchers say that could be making it harder to understand what effect climate change is really having. See, to predict cyclones in the future, we need to understand how they’ve behaved in the past. And we’ve only been tracking North Atlantic hurricanes with high-resolution satellites since 1972.

Now, records do go back to 1851, but the earliest observations mostly depended on people on land or on ships actually running into hurricanes. Which doesn’t exactly catch them all. So, the authors of this paper wanted to answer the question: has there actually been a trend towards more intense hurricanes in the North Atlantic over the last century?

They started their analysis from an interesting observation: the proportion of recorded Atlantic hurricanes that make landfall in the US, as a fraction of the total North Atlantic hurricanes, has decreased over time. So it’s possible that the ratio has decreased because we’ve gotten better at spotting all the hurricanes that don’t hit the US. It’s also possible that where they form is shifting around.

And that changes where they hit. The researchers used the data we do have to try to reconstruct a more accurate record of historical storms from 1851 to 1971. To do this, they built a model that cross-referenced tracks and characteristics of storms from years with complete records against ship logs from years with incomplete records.

While the model does rely on some pretty big assumptions, they were able to estimate about how many hurricanes may have been missed, and how much variability there is year to year in hurricane activity. More importantly, the study says there really isn’t evidence to suggest that our current glut of major hurricanes is that unusual over the long term, or that it’s part of a century-long trend. Instead, the trend we're seeing in the satellite era of more and worse storms from 1979 onwards looks to be just a natural rebound from a decrease in activity in the 60s and 70s.

Several explanations for this dip have been proposed, some natural and some caused by humans. These researchers, however, agreed with an earlier hypothesis that it may be a result of air pollution. So the idea is, we belched so much stuff into the air around that time that it obscured the sun and decreased ocean surface temperatures.

And tropical cyclones need very warm water to form and build in intensity. But the researchers also think it’s even more complicated than that. They say that these complicating factors could actually be making it more difficult to see what effect climate change is really having, from the data we have available.

In other words, far from letting humans off the hook, this study shows how much effect we may be having on this planet, and how hard we’re making it on ourselves to untangle all those threads. Thanks for watching this episode of SciShow News. If you would like to support what we do here, consider joining our amazing community of patrons.

Not only do you get to be one of the cool kids with access to our ridiculous blooper reels and et cetera, you will also be making SciShow possible. And to those of you who are already patrons: Thanks! [♪ OUTRO].