Prior research has shown that chronic alcoholism is associated with numerous olfactory deficits in odor judgment, odor identification, odor sensitivity, and the ability to qualitatively discriminate between odors.
New findings indicate that olfactory deficits among alcoholics are associated with prefrontal cognitive dysfunction, specifically, impairment in the functional integrity of the prefrontal lobe.
Results are published in the August issue of Alcoholism: Clinical & Experimental Research.
"Both frontal and medial temporal lobe brain regions play a major role in olfactory functioning, particularly in the abilities of odor quality discrimination and identification," said Claudia I. Rupp, clinical neuropsychologist and assistant professor in the department of psychiatry at Innsbruck Medical University, and corresponding author for the study.
"Given that alcohol can cause brain damage and dysfunction in frontal and medial temporal brain regions, and that neuropsychological tasks such as executive function and memory may represent sensitive measures of the integrity of these brain areas, we were interested in whether olfactory deficits in alcohol dependence are related to executive dysfunctions or memory impairments," she said.
Rupp and her colleagues examined 32 alcoholics (18 males, 14 females) and 30 healthy "controls" (16 males, 14 females) that were matched on age, gender and smoking status. All participants were assessed in three areas: olfactory function (detection threshold, quality discrimination, identification), executive function (using the Wisconsin Card Sorting Test), and memory (using the German version of the California Verbal Learning Test).
"We found that the alcoholics, when compared to the controls, were impaired in all three domains investigated: olfactory functions, executive function, and memory," said Rupp. "We also found that impairments in all three domains appear resistant to early recovery after alcohol drinking stopped. Furthermore, olfactory discrimination deficits appear to be associated with executive function impairment. Collectively speaking, our results suggest that olfactory discrimination deficits and executive function impairment may share a common neural substrate - that is, a pathological process may be mediating both deficits - most likely dysfunctional mechanisms involving the frontal lobe."