Retrograde amnesia is the inability to recall memories before the amnesia began, although you can still form new memories. This type of amnesia is usually caused by a brain injury or stroke. Anterograde amnesia is the inability to form new memories after the amnesia began. You can recall old memories but can’t store new ones. This type is often caused by damage to your brain’s hippocampus, which is responsible for forming memories. It is possible to have both types of amnesia at the same time.