Thank you.
So we know that mefloquine and the related quinolines are neurotoxic and we know that this neurotoxicity is demonstrated in animal models. It affects very specific areas of the brain stem and limbic system. As Dr. Ritchie was alluding to, on animal model studies, these drugs cause microscopic lesions in particular areas of the brain and brain stem, and based on our knowledge of neuroanatomy and neurophysiology, we would expect that lesions in those areas manifest as certain signs and symptoms.
For example, if there were tiny microscopic lesions in the vestibular nuclei in the brain stem that control the balance sense and that contribute to our orientation in space, such lesions would manifest as chronic disequilibrium, dizziness, a sense of vertigo and an abnormal gait. This is precisely what we see in veterans who complain both of psychiatric symptoms from mefloquine and of these symptoms.
These veterans who return home complaining of persistent nightmares, anxiety, depression and cognitive dysfunction, on careful examination by clinicians such as neuro-optometrists or neuro-otologists, are found to have evidence of central—meaning brain stem—visual or vestibular dysfunction.
We have a mechanism to explain this. It's not just PTSD. It's not just traumatic brain injury. The most parsimonious explanation for this is that they were exposed to a neurotoxicant that resulted in permanent dysfunction in their brain stem, and this explains the chronic disability.