This post was originally published on October 6, 2014.
Anyone who doubts the addictiveness of cocaine should consider the fact that some people keep using it until their brains bleed. Literally. We’ve known for some time that cocaine can sometimes cause strokes and aneurism-like bleeding inside the brains of its users—because we see it happening from the outside—but until recently, scientific imaging tools were too crude to get an accurate picture of what really goes on inside the brain of a cokehead.
This Is Your Brain on Drugs
Now, scientists at Stony Brook University have developed a new way to see how drugs like cocaine affect the blood vessels in the brain. These are the first images to capture what we already know—that coke disrupts the flow of blood to the brain. And it’s not a pretty picture.
To get these images, yet another bunch of mice had to get high. Whether the mice received a moderate dose of cocaine each day or a larger dose all at once, the images showed the blood flow in their brains slowing to an alarming pace. And for the first time, researchers were able to directly observe cocaine-induced microischemia—when the brain’s blood flow shuts down altogether—which happens just before a stroke.
It’s not that technology hasn’t been able to see inside our brains before. But earlier methods of imaging blood flow had always come with limitations. One common technology, fMRI, is great at capturing a wide field of view but doesn’t have a high enough resolution to capture what goes on inside the tiniest blood vessels, called capillaries. Conversely, higher-res techniques like two-photon microscopy (which follows actual blood cells around using fluorescent dyes) can only look at a few vessels at a time, missing the big picture.
The new technique is the first to offer the best of both worlds: a big picture at a high resolution. Called optical coherence Doppler tomography (ODT for merciful short), it works by literally shooting lasers at the blood vessels. Then, when the laser beams bounce back off the blood cells, researchers can determine the speed of the blood flow by measuring the change in the light’s frequency. If the name Doppler sounds familiar, you may be remembering high school physics. ODT employs a version of the same “Doppler effect” that makes sirens sound different when they’re coming towards you than they do passing you by.
ODT has actually been in use for a few years, but until now it could only pick up on a limited range of blood speeds and hadn’t been sensitive enough to work at the level of the capillaries. The upgraded ODT method uses something called “phase summation” (I don’t know either) that allowed it to work around both these snags, so that now we can get an accurate picture of what happens in your tiniest blood cells when you blow rails. Better still, unlike methods using fluorescent dyes, the laser beams don’t have side effects or cause drug interactions
Not Quite Down with ODT
There’s still a few more issues with ODT, though. For one, it doesn’t work when the blood vessel is perpendicular to the laser beam, which leaves its images full of dark gaps for researchers to “fill in.” A bigger problem is that ODT can only penetrate 1-1.5 millimeters (the width of the credit card you’re chopping up your lines with) below the surface. So yeah, it’s great for mice, but for humans it would mostly be useful when the brain is exposed, such as during an operation.
Being able to accurately map blood flow could help facilitate brain surgery, but until a newer version can probe deeper, its human applications will be limited. But as for providing a scary picture of your actual brain on drugs, it’s super effective.