MRI Shows Memory Changes Following Traumatic Brain Injury

MR imaging demonstrates that mild traumatic brain injury affects working memory function, even if there is no obvious change in behavior, according to a small study published in the September issue of the journal Radiology.

Researchers in Taiwan studied the brain activation patterns of 20 patients who had experienced a mild traumatic brain injury (MTBI) within the previous month and 18 healthy control subjects. The goal was to analyze the brain patterns in response to tests of working memory.

The subjects were assessed with functional MR imaging and all study participants underwent a series of tests involving number memory; digit span, a memory test for how many numbers a person can remember in a sequence; and a continuous performance test, which measures a person’s sustained and selective attention and impulsivity.

The findings revealed that brain activation patterns differed between the subjects who had sustained a MTBI and the controls in response to increased working memory loads. While the controls maintained their ability to increase activation in the working memory circuitry with each increase in working memory load, those with MTBI were not as able to do so. This group had difficulty increasing activation in working memory circuitry under both moderate and high working memory load conditions.

The researchers also found that MTBI patients showed cerebral plasticity, shown by more activation in some areas outside and inside the working memory circuitry, as compared with the controls.

Nine MTBI patients underwent follow-up functional MR imaging six weeks after the initial imaging and, compared to baseline, these patients showed an improvement in activation in response to increased working memory loads.

“MTBI-induced differences in working memory functional activity were observed even though differences in behavioral performance between MTBI patients and controls were absent,” the authors said, “which suggests that this approach may increase sensitivity to MTBI compared with neuropsychological evaluation alone.”