The two disorders often carry similar symptoms, such as irritability, restlessness, hypersensitivity to stimulation, memory loss, fatigue and dizziness. If someone is rating high on an mTBI scale, for example, that person may also rate high for PTSD symptoms. The researchers used electroencephalogram, or EEG, a test that measures electrical activity in the brain. The size and direction of the brain waves can signal abnormalities. The study included 147 active-duty service members or veterans who had been exposed to blasts in Iraq and Afghanistan. Of those, 115 had mTBI, which accounts for nearly 80 percent of all traumatic brain injuries. Forty of the participants had PTSD, and 35 had both conditions.