Alcoholics' Smell Deficits Linked to Frontal Lobe Impairment

July 25, 2006

INNSBRUCK, Austria -- Impaired olfactory function among chronic alcoholics appears to be associated with prefrontal lobe cognitive dysfunction, researchers here reported.

INNSBRUCK, Austria, July 25 -- Impaired olfactory function among chronic alcoholics appears to be associated with prefrontal lobe cognitive dysfunction, researchers reported.

Chronic alcoholism is associated with numerous olfactory losses, such as odor judgment, identification, and sensitivity, according to an online report in the August issue of Alcoholism: Clinical & Experimental Research. Deficits in both smell and cognitive competence may derive from a common neural substrate, most likely dysfunctional mechanisms involving the front lobe,

In a controlled study of alcohol-dependent patients, the researchers assessed the role of neurocognitive tests (executive function and memory) sensitive to the integrity of brain areas that are also crucial in olfactory processing.

Executive function (the ability to form and shift conceptual sets, for example), a frontal lobe function, but not memory, a medial temporal lobe function, was linked to olfactory loss, Claudia Rupp, Ph.D., of Innsbruck Medical University here, and colleagues reported.

Dr. Rupp's team examined 32 alcoholics (18 men; 14 women), with a mean history of 19.4 years of regular alcohol consumption and 9.3 years of alcoholic dependence, and 30 controls (16 men; 14 women). All participants were matched for age, gender, education, general cognitive ability, and smoking status.

Olfactory function (detection threshold, quality discrimination, identification) was assessed with the Sniffin' Sticks Test battery. Executive function was measured with the Wisconsin Card Sorting Test (WCST); memory with the German version of the California Verbal Learning Test.

Compared with the healthy controls, the alcoholics were significantly impaired in all three investigated olfactory functions (P

Dr. Rupp said that these findings help support the hypothesis that the frontal lobes, which are particularly vulnerable to alcoholism-related damage, may be involved in the development of addiction and may play a key role in understanding the neurobiology of alcoholism.