In this issue

C is best defined as the acquiring, storing, retrieving, and use of knowledge. Cognitive impair­ ment has long been linked with the chronic abuse of alcohol. Because al­ coholics express many types and de­ grees of cognitive deficits, however, defining a deficit pattern has been a complex and inexact task. Drs. Denise L. Evert and Marlene Oscar­Berman describe theoretical models devel­ oped by scientists to better character­ i z e t h e c o g n i t i v e i m p a i r m e n t s observed in alcoholics. The authors also discuss the experimental evi­ dence supporting and challenging each model. (pp. 89–96)


ASSESSING COGNITIVE IMPAIRMENT
T he fact that excessive alcohol con sumption can impair cognitive functioning is well documented in the alcohol literature. Yet the descriptions of how impairment has been assessed ofte n are i n ad equat e. Dr. Sara Jo N i xo n re v i e ws a sa m pli n g o f t h e plethora of assessment tools currently used to evaluate alcohol's impact on cognitive functioning. These tools are based on different testing princi ples: Some instruments allow assess me nt o f ov er al l i n t el l i g en ce a n d cognitive functioning, whereas others analyze only specific cognitive do mains. By choosing the appropriate assessment tool for each patient and research situation, researchers can gain a clearer understanding of alcohol's effects on the brain. (pp. 97-103) WHEN ALCOHOLISM AFFECTS MEMORY FUNCTIONS: MRI OF THE BRAIN D espite serious memory deficits, alcoholic amnesics may perform normally on certain tests that require learning, although they may not be able to recall the information learned. B ec a u s e of t hi s p h e n om en o n, r e searchers have postulated that inde pendent memory mechanisms may exist for implicit (unconscious) and ex plicit (conscious) memory. Magnetic resonance imaging (MRI) makes it possible to examine directly the rela tionship between brain abnormalities and memory impairment. MRI stud ie s sh o w t h a t d a ma g e t o sp ec i fi c brain structures is associated with particular memory defects. Research ers Drs. Terry L. Jernigan and Arne L. Ostergaard discuss results of re cent MRI studies which suggest that the observed distinction between im plicit and explicit memory does not require the existence of independent memory mechanisms. (pp. 104-107)

EVENTRELATED POTENTIALS AND COGNITIVE FUNCTION IN ALCOHOLICS
S ubtle cognitive defi cits c an be studied using eventrelated poten tials (ERP). These brain waves are elicited in response to sensory stim uli to provide an immediate record of the brain activity associated with information processing. Drs. Bernice Porjesz and Henri Begleiter discuss the abnormal ERP patterns found in alcoholics. Some ERP abnormalities m a y b e c o n s e q u e n c e s o f h e a v y drinking, whereas anomalies that are not a lt ered w it h prolonged abst i nence may antecede the develop ment of alcoholism. The authors also review evidence indicating that ERP characteristics are themselves geneti cally determined. (pp. 108-112)

ALCOHOLRELATED THIAMINE DEFICIENCY: IMPACT ON COGNITIVE AND MEMORY FUNCTIONING
W ernickeKorsakoff syndrome (WKS) is one of the best rec ognized and identified neurologic disorders associated with chronic al cohol abuse. In addition to other cog ni tive de f i ci ts, WK S p ati ents a re unable to learn and form new memo ries and to remember past events. Dr. Philip J. Langlais reviews studies in human patients and laboratory ani mals which suggest that inadequate levels of vitamin B 1 (thiamine) may contribute to the brain damage and cognitive impairments characteristic of WKS. Dr. Langlais then describes the link between alcohol, thiamine deficiency, and the disruption of es sential brain regions. (pp. 113-121)

THE ROLE OF LIVER DISEASE IN ALCOHOLINDUCED COGNITIVE DEFECTS
L iver cirrhosis, a consequence of chronic alcohol abuse, prevents the liver from effectively eliminating toxic metabolic products from the bloodstream. Consequently, toxic substances reach the brain, where they can disrupt normal brain func tioning. The most prevalent brain disorder resulting from liver dys f u n c t i o n i s p o r t a l s y s t e m i c e n cephalopathy (PSE). PSE progresses from subtle signs, such as anxiety and depression, to severe complica tions, such as hepatic coma. As Dr. Roger Butterworth describes, the ex act correlation between cirrhosis, toxic substances (such as ammonia), and cognitive and motor dysfunctions stemming from PSE still are under in tense investigation.

IN THIS ISSUE
and Thomas Roth propose that alcohol induced sleepiness does indeed con tribute to memory impairment. Such a correlation could mean that any c ondit io n t h at i nduc es s le epine s s may increase the risk of memory im pairment after alcohol consumption.

RECOVERY OF COGNITIVE FUNCTIONING IN ALCOHOLICS: THE RELATIONSHIP TO TREATMENT
A n encouraging observation is that a ll im p ai r ed a lco h o li cs s h o w some degree of recovery of cognitive and behavioral functioning once alco hol use is discontinued, according to Dr. Mark S. Goldman. Moreover, re covery can be facilitated using meth ods such as repeated mental exercises. Dr. Goldman reviews the nature and course of recovery from alcoholrelated deficits and offers strategies for en hancing this process. He also dis cusses growing evidence that supports an as s oc ia tion b et w een co g n i ti ve functioning and treatment outcome. (pp. 148-154)