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19 March 2014

Sea lions develop epilepsy similar to humans

Sea lions are under threat from domoic acid, a neurotoxin that can cause memory loss, tremors, convulsions and death. The toxin is carried in algae, which in recent years has been proliferating along the coast of San Francisco Bay and beyond, and the sea lions ingest it when feeding on small contaminated fish.

Sea lions develop epilepsy

Sea lion being rescuedAs a result of the exposure, the sea lions develop a form of epilepsy that is very similar to that in humans, according to a new study led by researchers from Stanford University School of Medicine and published online today (19 March) in the Journal of Comparative Neurology.

The sea lions suffer damage in the hippocampus – the brain’s memory centre – which mimics the damage in humans with temporal lobe epilepsy, said lead author of the study Paul Buckmaster, a Stanford veterinarian and expert in epilepsy in animals.

He said; 'We found there was a loss of neurons in specific patterns that closely matched what is found in people.' The researchers also noticed a pattern of rewiring in the brains of the animals that resembled that in humans with epilepsy.

Developing treatments

He added that sea lions could serve as good models for studying the disease and developing much-needed treatments.

The hope is that the new findings will help lead to interventions to prevent seizures in the animals and lead to better treatments for them, as well as their human counterparts.

Temporal lobe epilepsy is one of the most common forms of epilepsy in humans and has no cure. It can be caused by a head injury, high fever or lack of oxygen, resulting in seizures. Seizures caused by epilepsy may be treated with anti-convulsive medication or, in some cases, surgery.

There is one documented case of a patient who was found to have developed temporal lobe epilepsy following exposure to domoic acid. The 84 year old Canadian was one of more 250 people who became ill in 1987 after eating mussels from Prince Edward Island that were found to be contaminated with domoic acid. The man, who suffered nausea, vomiting, coma and convulsions, initially recovered but was diagnosed a year later with temporal lobe epilepsy.