Memory functioning can be disrupted by alcoholism prior to later-stage Korsakoff's syndrome, a neurological disorder generally linked to alcohol abuse, states a new study.
The researchers examined associative memory, used in remembering face-name associations, in alcoholics.
Alcoholism can disrupt memory functioning well before incurring the profound amnesia of Korsakoff's syndrome. For example, associative memory - used in remembering face-name associations - can be impaired in alcoholics.
A study of the cognitive and brain mechanisms underlying this deficit, through testing of associative memory performance and processing in study participants during structural magnetic resonance imaging (MRI) scanning, have found that impaired learning abilities are predominantly associated with cerebellar brain volumes.
"There are several memory systems and alcoholism does not disrupt all of them," explained Edith V. Sullivan, a professor in the department of psychiatry and behavioral sciences at Stanford University School of Medicine, and corresponding author for the study. "Chronic alcohol consumption mainly affects episodic memory and working memory."
Episodic memory is the memory system that 'files' personally experienced events associated with a precise spatial and temporal context of encoding, and it appears to have an unlimited capacity.
"For example, episodic memory includes memories of vacation such as: 'when I went to Paris with my husband, I ate a delicious ratatouille for dinner in a very cute restaurant; I can remember the place, how I was dressed, and how I burned my tongue when I tasted the meal,'" said Sullivan, quoting Anne-Lise Pitel, the lead author.
"Such memories are unique to the individual. Episodic memory is impaired in some alcoholics, who may have difficulties in remembering a grocery list, a route to a new restaurant, or new face-name associations as encountered in a new job."
Associative memory is a component of episodic memory, she added.
Conversely, working memory is a short-term memory system with a limited capacity, which enables temporary storage and manipulation of information, which is quickly forgotten unless consolidated into a long-term storage system.
"Alcoholics have deficits of working memory resulting in difficulties like holding a phone number in mind while dialing it," Sullivan said.
"This study focused on a cognitive process essential in daily living," said Sara Jo Nixon, a professor in the department of psychiatry at the University of Florida.
"Effective associative learning and memory processes such as learning that two items 'go' together and remembering this link or association later are essential for successful interactions throughout our personal and professional environments.
"Learning the names of new friends, colleagues or acquaintances is only one example of this type of learning, but it is of particular social and personal importance."
Sullivan, Pitel, and their colleagues presented learning tasks to two groups: 10 alcoholics (8 men, 2 women) recruited from community treatment centers, outpatient clinics, and hospitals, as well as 10 "controls" or non-alcoholics (5 men, 5 women) recruited from the local community.
Tasks were either associative such as face-name, or single-item such as face or name.
The participants' recognition retrieval was designated as "shallow encoding" if the face was recalled as that of a "man," or "deep encoding" if the face was recalled as "honest."
"Alcoholics had impaired learning abilities for both face-name association and single face or name. Learning performances correlated with different brain regions in alcoholics from those of controls; in particular, associative learning in alcoholics was related to cerebellar brain volumes measured on MRI."
This pattern was different from associations we observed in controls, who showed relations between associative learning and limbic system volumes," Sullivan added.
The study will be published in Alcoholism: Clinical 'n' Experimental Research and is currently available at Early View.