" The side effect that has been feared is the risk of brain swelling. We call this aria, and there is also a side of that called aria H which is little micro-hemorrhages. This can sound quite terrifying. This is one reason why Biogen has been very slow to escalate the dosage of Aducanumab in its trials. It turns out that aria, and it’s other branch aria H is very manageable and can be traced by titrating Aducanumab up to the higher dose. Also, the vast majority of people who have aria show this on an MRI but have no symptoms at all. Aria can also go away with time. We can expect this and monitor this - but this doesn’t mean because it is present you have to stop taking the our drug or drop out of our study. "