Increased impulsivity after injected alcohol predicts later alcohol consumption in rats: Evidence for "loss-of-control drinking" and marked individual differences.

“Alcohol administration in rats produced a dose-dependent increase in impulsive choice (Evenden and Ryan 1999; Poulos et al. 1998), contrasting with the lack of alcoholinduced effects on DD in humans.”

“Along these lines, Reynolds et al. (2006) found that self-report measures of impulsivity did not correlate strongly with behavioral tasks assessing aspects of impulsive behavior.”

“However, this possibility is inconsistent with some non-human animal discounting research showing alcohol and diazepam effects (e.g.Evneden and Ryan, 1996; Poulos et al., 1998; Tomie et al., 1998).”

“Critically, the high reactive animals drank a significantly greater amount of the more concentrated alcohol solutions (Poulos et al., 1998), again affirming the relationship between high levels of impulsivity on the delaydiscounting paradigm and subsequent alcohol intake.”

“Individual differences in impulsivity may also be substantial and predictive of between-subjects differences in alcohol drinking (Poulos et al., 1995, 1998).”

“Limited access also induces rats to drink ethanol, but in daily binges such as 1 h/day (Cichelli & Lewis, 2002; Kunin et al., 2000; MacDonall & Marcucella, 1979; Marcucella & Munro, 1987; Poulos et al., 1998; Smith et al., 1999).”

“In rats, alcohol increases the preference for small immediate rewards over larger delayed rewards [139, 140], but in humans, the effects of acute alcohol on delay discounting are inconsistent across studies [141-143], which may be partly attributable to methodological differences between studies [142].”

“To date, there is limited evidence on this question: In rats, cognitive impulsivity correlates with voluntary ethanol intake (Poulos et al., 1998), and displays of impulsivity in monkeys predict patterns of ethanol drinking (Higley & Linnoila, 1997).”

“These null findings are inconsistent with several nonhuman-animal studies that have shown diazepam and alcohol effects on delay discounting (Evenden and Ryan, 1996; Poulos et al., 1998; Tomie et al., 1998).”

“…using different paradigms of impulsivity in rats, including the delay of reinforcement paradigm where ethanol increased impulsive behaviour (Evenden and Ryan 1999; Olmstead et al. 2006; Poulos et al. 1998; Tomie et al. 1998), suggesting that ethanol increases impulsive choice and impulsive action.”

“Priming with alcohol increases the desire to drink (De Wit and Chutuape, 1993; De Wit, 1996) and may have disinhibiting effects that lead to loss of control of drinking (Collins, 1993; Poulos et al., 1998; Bensley, 1991).”

“METHODS ARTICLE published: 27 January 2014 doi: 10.3389/fnint.2014.00003 Isolating the delay component of impulsive choice in adolescent rats”

“This hypothesis is in accordance with the results of the study by Poulos et al. (1998), who showed that injecting alcohol in rats produced a dose-dependent increase in impulsivity.”

“Introduction A growing body of animal and human evidence suggests that alcohol can attenuate control processes, leading to disinhibited and impulsive behaviour, which may relate to risky and/or excessive drug taking (Poulos et al., 1998; Fillmore, 2003; Volkow et al., 2004).”

“[12] showed that injecting alcohol in rats produced a dose-dependent increase in impulsivity, and that individual differences in impulsive reactivity to injected alcohol strongly predicted the magnitude of voluntary alcohol intake.”

“The effect of alcohol on impulsivity was not as strong as that previously reported (Poulos et al. 1998), but baseline impulsivity scores were higher in our study due to a longer delay to the large reward (10 vs 5 s).”

“However, ethanol increased impulsive choice in rats pre-selected as high- and low-impulsive [19], suggesting that preexisting differences may not change the effects of ethanol on delay discounting.”

“Poulos and colleagues were among the first to assess how preexisting individual differences in impulsive decision-making in drugnaïve rats subsequently predict vulnerability to ethanol drinking (Poulos et al., 1995; Poulos et al., 1998).”

“These findings are supported by results from studies using different paradigms of impulsivity in rats, including the delay of reinforcement paradigm, where ethanol increased impulsive behaviour (Poulos et al., 1998; Tomie et al., 1998; Evenden and Ryan, 1999; Olmstead et al., 2006), suggesting that alcohol given acute…”

“Common aspects of impulsivity comprise decreased inhibitory control, intolerance of delay or other costs of rewards, quick decision-making owing to lack of consideration, as well as other deficits, such as poor attention and hyperactivity (Daruna and Barnes, 1993; Poulos et al., 1998).”

“Others have reported similar effects of ETOH on impulsive choice (delay discounting) in rats (Evenden and Ryan 1999; Olmstead 2006; Poulos et al. 1998) and in humans using the Stop Signal Reaction Time Task (de Wit et al. 2000; Fillmore et al.”

“Treatments that induce reinstatement, including priming doses of drugs or exposure to stress increase DYN [1] and are also associated with increased impulsivity [16,17].”

“More impulsive animals, as measured by the inability to withhold responses or by delay discounting, exhibit higher rates of drug self-administration (Belin et al. 2008; Perry et al. 2008; Poulos et al. 1998).”

“On the one hand, animal research often demonstrates that alcohol leads to disinhibited behaviour, such as increased aggression (Miczek et al., 1993), impulsivity ( Poulos et al., 1998; Evenden and Ryan, 1999), and playfulness (Varlinskaya et al., 2001), consistent with the idea that alcohol is a general disinhibitor.”

“Notably, both animal (Poulos et al. 1998) and human (Weafer and Fillmore 2008) studies suggest individual variability in alcohol-induced impulsivity or response inhibition.”

“Humans and other animals that are highly susceptible to this effect tend to drink more when given free access to alcohol (Poulos et al., 1998; Weafer and Fillmore, 2008).”

“In these models, greater discounting of delayed rewards is predictive of increased drug taking (Perry et al., 2005; Perry et al., 2008; Poulos et al., 1998; Wilhelm and Mitchell, 2008) and results from exposure to multiple drugs of abuse (Dallery and Locey, 2005; Dandy and Gatch, 2009; Helms et…”

“T-maze paradigms have consistently shown an increase in DD with acute alcohol (Olmstead et al., 2006; Poulos et al., 1998).”

“, 2006), the majority of published studies using animal subjects have indicated that acute ethanol increases impulsivity in a delay discounting model (Evenden and Ryan, 1999; Hellemans et al., 2005; Olmstead et al., 2006; Poulos et al., 1998; Tomie et al., 1998; but see Wilhelm and Mitchell, 2012); that is, ethanol in…”

“Moreover, alcohol-induced disruptions of inhibitory control have been linked to risky behaviors such as excessive binge drinking in humans and laboratory animals (Poulos et al., 1998; Weafer and Fillmore, 2008).”

“Evidence from both human and rodent research indicates that acute alcohol administration enhances impulsivity, likely through its effects on inhibitory control (Poulos et al. 1998 ; de Wit et al. 2000; Olmstead et al. 2006; Dougherty et al. 2008 ; Adams et al. 2012).”