How does episodic memory develop in adolescence?

Key areas of the episodic memory (EM) network demonstrate changing structure and volume during adolescence. EM is multifaceted and yet studies of EM thus far have largely examined single components, used different methods and have unsurprisingly yielded inconsistent results. The Treasure Hunt task is a single paradigm that allows parallel investigation of memory content, associative structure, and the impact of different retrieval support. Combining the cognitive and neurobiological accounts, we hypothesized that some elements of EM performance may decline in late adolescence owing to considerable restructuring of the hippocampus at this time. Using the Treasure Hunt task, we examined EM performance in 80 participants aged 10–17 yr. Results demonstrated a cubic trajectory with youngest and oldest participants performing worst. This was emphasized in associative memory, which aligns well with existing literature indicating hippocampal restructuring in later adolescence. It is proposed that memory development may follow a nonlinear path as children approach adulthood, but that future work is required to confirm and extend the trends demonstrated in this study.

Episodic memory (EM) describes the ability to encode, store, and retrieve representations of previously experienced episodes and their temporal-spatial context (Tulving 1972). EM development continues well into the third decade of life (Ruggiero et al. 2016); however, its developmental trajectory after the preschool years remains controversial, with some studies suggesting linear improvements (Ofen et al. 2007) and others no improvement (Picard et al. 2012) or a nonlinear pattern (Tulving 1985; Keresztes et al. 2017). While there has been some debate as to the “defining features” of EM (Cheke and Clayton 2013, 2015) most theorists agree that it is not a unitary ability, instead reflecting the combination of a number of contributing features. Given that many of these studies used different methods for testing EM, and that different tests may emphasize different features (Cheke and Clayton 2013, 2015), it is likely that empirical differences reflect the fact that different features of memory may develop differently during later childhood and adolescence (Picard et al. 2012).The importance of understanding the developmental trajectory of EM in adolescence is highlighted in the close association between EM and other cognitive processes. EM is thought to support decision-making, particularly in the incorporation of memories into task- and goal-relevant responses (Murty et al. 2016); thus, immaturity of EM may influence the high levels of risk taking observed in adolescence. Adolescence also represents a period of vulnerability to the development of mental illness (Kessler et al. 2007). Evidence that deficits in EM have been linked to a number of mental health disorders such as depression (Goodwin 1997) and anxiety (Airaksinen et al. 2005) raises the possibility that individual differences in memory development during this period may influence this vulnerability. Finally, adolescence is a demanding time academically: During these school years, large quantities of knowledge must be acquired to be successful in exams, which have long-term impacts on individuals’ academic and professional future. It is therefore important to understand factors that may contribute to individual differences and challenges in learning and memory during this period.Memory development in adolescence has attracted considerable research attention in recent years, with the majority of work conducted on developmental trajectories of brain areas within the memory network. EM relies on a distributed network of brain areas, including the medial temporal and superior parietal lobes and the prefrontal cortex (PFC) (Simons and Spiers 2003). Each area within the network, as well as the network itself, shows protracted maturation across adolescence.