A recent study by researchers at the Stanford University School found that sea lions in California develop a type of epilepsy similar to what humans experience. The findings were published on March 19 in the Journal of Comparative Neurology.
The sea lions are exposed to domoic acid, found in algae bloom, which is increasing in frequency along the coast of California. The algae is a neurotoxin with several side effects, including memory loss, convulsion, tremors, and worst of all, death.
Other marine mammals, such as dolphins, could also be affected by the acid, as noted by co-author Frances Gullan. However, it is not known if this is the case, as they do not wash up on shore, though there is a possibility they could just drown in the open water following a seizure.
The domoic acid link with epilepsy in sea lions was made in 1998; however, what underlay their condition had perplexed scientists until now. The research involved studying the brains of affected sea lions. Buckmaster and colleagues found hippocampus damage, the area of the brain responsible for memory and similar to the condition of temporal lobe epilepsy in humans.
Temporal lobe epilepsy is the most common form of the disorder that affects 65 million people worldwide. According to epilepsy.com, 60 percent of all patients with the disorder have temporal lobe epilepsy, which can then be broken down to two different types. The type associated with the hippocampus, is known as medial, occurring in 80 percent of people with temporal lobe epilepsy and often resistant to treatment, along with being harder to detect on an MRI.
The cause for temporal lobe epilepsy is usually from brain injury, including head trauma or not enough oxygen in the brain. This injury would develop into epilepsy later on in life ranging from months to years. Sometimes, the only treatment is surgery involving a removal of the hippocampus, which can be a cure in some cases, but in turn affect an individuals memory.
The condition has been a huge concern for sea lions. Every year, a few hundred of them are rescued, but only half can be treated. Some suffer brain damage due to continuous seizures that last for hours, and thus they have to be euthanized. The study is noted by Buckmaster as being great progress in finding better treatments for the animals, along with humans with temporal lobe epilepsy.
The professor is currently planning further studies looking at the whole brain of the mammal, soon after it dies. He also has grants to look at exposure of domoic acid through the uterus. Buckmaster notes how it has been found that the algae also affects younger sea lions exposed before birth through the amniotic fluid and during the development stage of the nervous system. There is a belief that this is also similar in humans. Buckmaster said the goal is to prevent epilepsy from occurring in the sea lions by early intervention, and as a result, finding better treatments for humans as well.
By Kollin Lore