Troops who don't pass the smell test likely have traumatic brain injury

Decreased ability to identify specific odors can predict abnormal neuroimaging results in blast-injured troops, according to a new study. The olfactory system processes thousands of different odors, sending signals to the brain which interprets the smell by linking it to a past memory. If memory is impaired, as is the case with Alzheimer's disease, sleep deprivation, and acute traumatic brain injury, the task is not entirely possible.