Chronic Pain May Dim Memory

May 23, 2007 -- Chronic pain may distract the mind, hampering the memory-making process, according to a new Canadian study.

Learning more about chronic pain's effects on mental skills such as memory may one day lead to new treatments, note the researchers, who included Bruce Dick, PhD, of the University of Alberta.

They studied 24 adults with chronic pain who were in their mid- to late 40s, on average.

The patients' pain had lasted for at least six months. Their pain score was at least 4 on a scale ranging from 0 to 10, with 0 indicating no pain and 10 indicating the worst pain imaginable.

The patients, who were being treated at the university's Multidisciplinary Pain Centre, took memory tests twice -- once after getting a pain-relief procedure such as an epidural injection, and on another day when they hadn't had a recent pain-relief procedure.

The memory tests involved verbal memory (remembering specific words from sentences) and spatial memory (remembering how the letter "J" was shown on a computer screen).

Two-thirds of the patients performed worse on the tests on the days when they hadn't had a recent pain-relieving procedure. Spatial memory was particularly tricky for them, the study shows.

The results didn't seem to be tied to the patients' sleep problems, psychological distress, or age, note the researchers.

"Our findings suggest that pain may disrupt the maintenance of the memory trace that is required to hold information for processing and to later retain it for storage in longer-term memory stores," write Dick and colleagues.

They add that it remains to be seen whether attention training can offset those memory problems.

The study appears in the journal Anesthesia & Analgesia.