Episodic Memories and Their Relevance for Psychoactive Drug Use and Addiction

Abstract

The majority of adult people in western societies regularly consume psychoactive drugs. While this consumption is integrated in everyday life activities and controlled in most consumers, it may escalate and result in drug addiction. Non-addicted drug use requires the systematic establishment of highly organized behaviors, such as drug-seeking and -taking. While a significant role for classical and instrumental learning processes is well established in drug use and abuse, declarative drug memories have largely been neglected in research. Episodic memories are an important part of the declarative memories. Here a role of episodic drug memories in the establishment of non-addicted drug use and its transition to addiction is suggested. In relation to psychoactive drug consumption, episodic drug memories are formed when a person prepares for consumption, when the drug is consumed and, most important, when acute effects, withdrawal, craving, and relapse are experienced. Episodic drug memories are one-trial memories with emotional components that can be much stronger than “normal” episodic memories. Their establishment coincides with drug-induced neuronal activation and plasticity. These memories may be highly extinction resistant and influence psychoactive drug consumption, in particular during initial establishment and at the transition to “drug instrumentalization.” In that, understanding how addictive drugs interact with episodic memory circuits in the brain may provide crucial information for how drug use and addiction are established.

Basal Hippocampal Activity and Its Functional Connectivity Predicts Cocaine Relapse

“…Of particular relevance to our findings, stronger intrinsic connectivity between the hippocampus and PCC during rest predicts superior performance on measures of episodic memory (70) and disruption of this connection is associated with age-related memory decline (71). In our CUD individuals who relapsed, heightened pHp-PCC rsFC may reflect strengthened episodic memories associated with cocaine use (72,73). This strengthened memory circuitry may underlie the persistent obsessive thoughts, or rumination, commonly observed in addicted individuals (74,75).…”

Offending: Drug-related expertise and decision making

“…Cognitive goals are also dominated by subconscious goals at the neurophysiological level. And while stimulus (S)-response (R) associations are formed due to repeated drug administration (Robinson & Berridge, 2003), it is also possible to form conscious goal representations after a single drug exposition via episodic memory (Müller, 2013). At a physiological level, reward circuitry neurons show increased dendritic branching and synaptic spine density; this is also found in neocortical structures (Robinson & Kolb, 2004).…”

CaM Kinases: From Memories to Addiction

“…Thereby, information is encoded within different behavioural systems, which can be summarized as "drug memories" [5,[7][8][9] (Box 1). It is believed that an intensification of these memories together with a loss of impulse control (compulsivity) is responsible for the transition from controlled drug use to addiction [10][11][12].…”

“…It is an autobiographical memory on the 'what', 'where', and 'when' of the personal drug encounters. This may include memories of subjectively experienced acute drug effects, e.g., the mental states the drug induced [9].…”