Medical professionals diagnose TBI using a variety of tests. They may rely on brain imaging through a CT scan or an MRI. They may utilize the Glasgow Coma Scale, which assesses physical abilities such as speech and movement to determine the severity of the injury (mild, moderate, or severe). They may assess behavioral measures such as speech, cognition, and memory. They may take a blood test to identify proteins that are often elevated after a head injury. Diagnosis can be difficult because it can sometimes be challenging to distinguish between TBI and other conditions such as post-traumatic stress.