Paths to hippocampal damage in neuromyelitis optica spectrum disorders

This research explores how the hippocampus, a brain region crucial for memory and learning, is affected in neuromyelitis optica spectrum disorders (NMOSD). NMOSD is an autoimmune disease where the body's immune system attacks the central nervous system, often leading to vision problems and spinal cord damage. The study found that damage to the hippocampus in NMOSD can occur in two main ways: either through direct attack on the hippocampus itself, or indirectly, as a result of damage in other areas of the brain and spinal cord. Direct attacks involve the destruction of astrocytes, support cells in the brain, leading to inflammation and neuronal damage. Indirect damage happens when lesions in the optic nerves or spinal cord cause nerve fibers to degenerate backwards towards the hippocampus, ultimately leading to hippocampal volume loss. These findings help explain why some NMOSD patients experience cognitive problems and depressive symptoms.

• 1
  Hippocampal damage in NMOSD can result from direct astrocyte injury and subsequent microglial activation and neuronal damage within the hippocampus.
• 2
  Hippocampal volume loss in NMOSD patients is associated with large tissue-destructive lesions in the optic nerves or spinal cord, leading to retrograde neuronal degeneration.
• 3
  Lesions with AQP4 loss can form anywhere in the hippocampus, and their location and size correlate with the size of the hippocampal subfields.