Hopkins investigates IEDs’ effects on brain

The structure and functions of the brain are highly complex, and in turn, the way it reacts to injury and insults can be perplexing. In fact, it is arguably the most complex and least understood structure in nature. Researchers at the Johns Hopkins School of Medicine have recently published some interesting and startling findings on the pathological effects observed in the brains of soldiers exposed to improvised explosive devices (IEDs).

An IED, a common weapon of choice for terrorists and insurgents, is a homemade device designed to cause death or injury by using explosives alone or in combination with chemical or biological toxins or radioactive materials. IEDs are hidden to avoid detection and improve effectiveness. Most are activated when the victim interacts with them in some way. Currently, IEDs are employed in Iraq and Afghanistan.

Bomb-induced brain damage is far from a new occurrence, with documented observations as far back as World War I when it was referred to as “shell shock.” It is only with the recent advent of modern technology that this type of damage to the human brain is beginning to be studied and understood.

Vassilis Koliatsos is a pathologist at the School of Medicine. Koliatsos and his team have recently published their discovery that IEDs may cause a unique injury. According to their report, soldiers who have survived an IED explosion may experience yet-to-be-revealed injuries to their brains that may cause social and psychological issues that manifest after they return home. Common side effects suffered by the veterans are depression, anxiety, post-traumatic stress disorder, adjustment disorder and substance abuse.

According to Koliatsos, examining the brain is like examining the life history of an individual. In the brains of veterans who experienced an IED explosion and later died, researchers observed specific pathological features that may be unique to these victims. Where these lesions occur and the extent of the damage that appears may be a clue to explaining the difficulties that some soldiers experience when trying to readjust to their former lives returning from duty.

Koliatsos and his colleagues studied amyloid precursor protein (APP) in this investigation. APP is a protein expressed in many tissues and concentrated in the synapses of neurons. It has been suggested that APP is a regulator of synapse formation and is involved in changes in brain structure, known as neuroplasticity. However, its major function is presently unknown. It has also been implicated in the formation of the plaques found in the brains of Alzheimer’s disease patients.

The researchers tracked APP, which routinely travels between nerve cells through an axon. When an axon is broken by a traumatic injury, APP cannot travel past the break, forming a build-up that induces swelling. Swelling can occur due to numerous forms of trauma; however, the type swelling produced in the brains of IED blast survivors was unique and was found in a honeycomb pattern adjacent to blood vessels.

These lesions were observed in various regions in the brains, including areas that are involved in memory, decision making and reasoning. They may have been remnants of normal nerve fibers that were broken at the time of the explosion or weakened fibers that were broken by some subsequent insult to the brain. The discovery of these lesions may eventually help in the treatment of soldiers who return traumatized from combat.