A longitudinal twin study of effects of adolescent alcohol abuse on the neurophysiology of attention and orienting

Abstract

Background: Long-term functional brain effects of adolescent alcohol abuse remain uncertain, partially because of difficulties in distinguishing inherited deficits from neuronal effects of ethanol and by confounds associated with alcohol abuse, especially nicotine exposure. We conducted a longitudinal twin study to determine neurocognitive effects of adolescent alcohol abuse, as measured with the auditory event-related potential (ERP) component P3, a putative marker of genetic vulnerability to alcoholism.

Methods: Twin pairs (N=177; 150 selected for intrapair concordance/discordance for alcohol-related problems at age 18½) were recruited from ongoing studies of twins born 1975-1979 in Finland. Alcohol and tobacco use were assessed with questionnaires at ages 16, 17, 18½, and ~25, and by a structured psychiatric interview concurrent with the ERP testing at mean age 25.8. During ERP recordings, subjects were instructed to detect target tones within a train of frequent "standards" and to ignore occasional "novel" sounds. To distinguish familial factors from ethanol effects, ERP and self-reported alcohol use measures were incorporated into hierarchical multiple regression (HMR) analysis, and intrapair differences in ERP were associated with intra-pair differences in alcohol variables.

Results: Novel-sound P3 amplitude correlated negatively with self-reported alcohol use in both between- and within-family analyses. No similar effect was observed for target-tone P3. HMR results suggest that twins' similarity for novel-sound P3 amplitude is modulated by their alcohol use, and this effect of alcohol use is influenced by genetic factors.

Conclusions: Our results, from a large sample of twins selected from a population-based registry for pairwise concordance/discordance for alcohol problems at 18½, demonstrate that adolescent alcohol abuse is associated with subtle neurophysiological changes in attention and orienting. The changes are reflected in decreased novel-sound P3 amplitude and may be modified by genetic factors.

Fig. 1

Grand-average event-related potential (ERP) waves (novel) and difference waves (novel minus standard) in “Low-drinking” and “High-drinking” twins, indicating a decrease of P3 amplitude for the novel sounds associated with alcohol use, as measured with the variable “Maximum number of drinks consumed in a 24-hour period” (MAX-D24) at age 25. “Low-drinking” twins are those in the lowest decile (N = 36) of maximum drinks consumed in a 24-hour period (MAX-D24 mean = 6.7, SD = 2.4) and “High-drinking” twins are those in the highest drinking decile (N = 36, MAX-D24 mean = 36.7, SD = 3.4) drawn from the total ERP twin sample.

Fig. 2

Grand-average event-related potential (ERP) waves in “Low-drinking” and “High-drinking” twins for the target tones. Alcohol use is measured with the variable “Maximum number of drinks consumed in a 24-hour period” (MAX-D24) at age 25. Same 2 groupings, N = 36 each, as in Fig. 1. EEG, electroencephalogram.

Fig. 3

Grand-average event-related potential (ERP) waves in “Low-drinking” and “High-drinking” twins for the standard tones. Alcohol use is measured with the variable “Maximum number of drinks consumed in a 24-hour period” (MAX-D24) at age 25. Same 2 groupings, N = 36 each, as in Fig. 1. EEG, electroencephalogram.