Nicotine effects on immediate and delayed verbal memory after substance use detoxification

Abstract

Decrements in verbal memory are commonly reported by detoxified treatment-seeking individuals. Although acute nicotine has been shown to improve attentional performance, its effects on verbal memory in substance abusers have not been addressed. Treatment-seeking alcohol-dependent (ALCs, n = 29; 14 male), illicit-stimulant-dependent (predominantly cocaine; STIMs, n = 25; 15 male), and alcohol- and illicit-stimulant-dependent (ALC/STIMs, n = 50; 35 male) participants with comorbid nicotine dependence were studied. Subjects had been abstinent from their drugs of choice for 41 (±18) days and were in short-term abstinence from tobacco (∼8–10 hours). Subjects received double-blind administration of either transdermal nicotine (high dose: 21/14 mg for men and women, respectively, or low dose: 7 mg) or placebo. The Logical Memory (LM) subtest from the Wechsler Memory Scale–Revised (WMS–R) was used to assess immediate and delayed verbal memory recall. Results indicated that STIMs receiving the high dose of nicotine recalled more words at immediate recall than STIMs who received placebo. Trend level differences were also noted at delayed recall between STIM nicotine and placebo doses. Nicotine failed to impact either recall in alcoholic subgroups. Although not the primary focus, results also revealed differences in the forgetting rates between the groups with the ALC/STIMs demonstrating the steepest forgetting slope. In summary, this study suggests that nicotine effects may be differentially experienced by substance-using subgroups; that nicotine may have a direct effect on memory; and that in considering neurocognitive processes (e.g., encoding vs. retrieval), underlying endpoint indicators (e.g., correct recall) may be critical in predicting outcomes.

Keywords:

• Alcoholic
• Verbal memory
• Substance dependent
• Nicotine
• Wechsler Memory Scale–Revised

Acknowledgments

Research was performed in the Neurocognitive Laboratory (director S.J.N.), at the Department of Psychology, University of Kentucky, Lexington, KY, and Department of Psychiatry, University of Florida, Gainesville, FL. Support was provided in part from NIDA (National Institute on Drug Abuse) R01 DA-13677 (to S.J.N.). A preliminary abstract of this work was published in Alcoholism: Clinical and Experimental Research (2008, Suppl. 6, p. 175A). Additional salary support was provided through U54RR025208 (D. Nelson, PI, Nixon, Co-I). The authors would like to thank Christine Stilz, Amanda Ross, and Andy Shelton for their assistance in data collection.