1. We expect to find that the silent cerebral infarct (SCI) rate is two fold higher in patients treated without caplacizumab. We also expect to find that the rate of mild and major cognitive impairment in patients treated with caplacizumab within 3 days of starting plasma exchange will be lower than patients treated without caplacizumab.
2. We expect that the differences in cognitive impairment in cases (caplacizumab) versus controls (no caplacizumab) will persist on serial evaluation 1 year later. We also expect that there will be differences in these groups even after adjusting for time since episode and severity of presentation.
3. We expect to find that SCI and cognitive impairment is associated with worse scores on the health related quality of life instrument (SF-36)
4. Based on studies in non-TTP populations, we expect to find that the rate of incident stroke over the period of follow up is at least 2 fold higher in patients that have SCI compared with patients who do not have SCI

Inclusion Criteria:

1. Age >= 18 years
2. Confirmed iTTP based on ADAMS13 activity < 10 % (or 10-20% with positive inhibitor or antibody) during an acute iTTP episode
3. Only 1 episode of iTTP that was treated with plasma exchange and caplacizumab started within 3 days of diagnosis (or if more than 1 episode, then all episodes treated with plasma exchange and caplacizumab started within 3 days of diagnosis)

Exclusion Criteria:

1. Any contraindication for MRI (metallic implants, shrapnel, MRI incompatible stents, etc)
2. Unable to speak, read or understand instructions in English (for NIH ToolBox)
3. Combination of iTTP episodes treated without caplacizumab or with caplacizumab.
4. Caplacizumab started at >= 4 days from diagnosis or for refractory iTTP

Adults with iTTP