A new examination of memory retrieval among recovering alcoholics has found lower activation than among nonalcoholics in key areas of the brain even in the absence of demonstrable brain structural damage.
Researchers refer to this alcohol-induced damage as “latent lesions.”
Results are published in the September issue of Alcoholism: Clinical & Experimental Research .
“Even in the alcoholic brain without apparent structural brain changes, some cognitive impairment exists,” said Motoichiro Kato, associate professor in the department of neuropsychiatry at Keio University in Japan. “We believed that the associated functional changes could be visualized by neuroimaging techniques.” Kato is also corresponding author for the study.
“Impairment in different aspects of cognitive, sensory or motor function can arise from problems with impairment in neurochemical systems that enable information to be carried quickly and efficiently between brain regions,” explained Edith V. Sullivan, professor in the department of psychiatry and behavioural sciences at Stanford University School of Medicine. “Such deficits in neurotransmission are not visible with conventional magnetic-resonance imaging methods. However, Doctor Kato used another method, functional magnetic resonance imaging (fMRI), which is sensitive to localized changes in brain-blood volume that occur when an individual engages in a cognitive or motor task. fMRI has been demonstrated to be useful in identifying compromised functional brain systems even in the absence of detectable brain lesions.”
Study authors gave a modified “false recognition task,” a word-matching exercise, to two groups: nine (8 men, 1 woman) alcoholic patients whose onset ages were less than 30 years of age and who were abstinent for an average of 40 months; and nine (7 men, 2 women) community-based “controls” matched on age and education. All participants were scanned with fMRI while performing the task.
Results showed that long-term memory retrieval induced by the task led to lower brain activity in the prefrontal lobes, anterior cingulate cortex, thalamus, and ventral striatum of the alcoholics than the controls.