A recent study examined impulsivity and poor inhibition in patients with traumatic brain injury (TBI).
Researchers observed patients with moderate to severe TBI and a non-TBI control group first subjected to two tests: a stop-signal task that tested the patients' ability to inhibit dominant or automatic motor responses and a negative task that measured how difficult it was for the patient to resist the intrusion of irrelevant information into memory of information. A questionnaire given to an informant of each patient assessed impulsivity.
Compared to a patient's pre-TBI condition, post-TBI patient conditions revealed increases in current urgency and lack of premeditation and perseverance. Compared to the control patient group, the TBI patient group performed poorer in the stop-signal and negative tasks. The data also suggests urgency experienced by TBI patients is related strongly to the patient's ability to control dominant or automatic motor responses.
Rochat L, Beni C, et al. How Inhibition Relates to Impulsivity after Moderate to Severe Traumatic Brain Injury. Journal of the International Neuropsychological Society. (July 2013).