Early Childhood Adversity Impacts Impulsive Decision-Making

Introduction

Early childhood adversity can involve a variety of negative exposures, ranging from physical and sexual abuse to chronic poverty (Anda et al., 2006; Burghy et al., 2012; Cohen et al., 2013). Evidence from population-based epidemiological studies have found that childhood adversity has significant detrimental impacts on an individual’s well-being (Cohen et al., 2001; Green et al., 2010; McLaughlin et al., 2012). People unluckily exposed to early childhood adversity are at elevated risk of developing severe mental disorders (schizophrenia, bipolar disorders, major depressive disorders, etc.) and self-destructive behaviors (alcoholism, substance use, etc.) (Barrett, 2009; Molnar et al., 2001; Troy et al., 2021).

Another negative consequence of early childhood adversity is impulsivity and, more specifically, impulsive decision-making. One meta-analysis (a study of existing studies) found that chaos in the household was inversely associated with child executive functioning and effortful control (Andrews et al., 2021). However, other recent research has found that early childhood adversity could enhance individuals’ executive functioning and result in adaptive strategies – a seeming contradiction. Identifying the factors that lead to these two different outcomes may explain why some people cope with more resilience and others with more vulnerability

In this article, I focus on the association between childhood adversity and impulsive decision-making, traumas that occur in early childhood, and their impact that accumulates during childhood development. The contradictory findings mentioned above will also be compared and discussed.

Early Childhood Adversity

Early adversity refers to a condition that threatens the satisfaction of needs and main goals of the individual, constrains their development, and leads to prolonged stress (Cicchetti & Toth, 1995). Adverse childhood experiences that occur before 18 can be broken down into three categories: (1) abuse, including emotional, physical, and sexual; (2) neglect, including emotional and physical; and (3) household dysfunction, including interpersonal violence, household substance abuse, household mental illness, parental separation or divorce, and incarceration of a household member (Lukasse et al., 2009).

Other researchers have further divided childhood adversity into two parts: experiences of deprivation and experiences of threat (McLaughlin et al., 2012). Deprivation is the absence of positive cognitive and social inputs. Threats, on the other hand, include events that involve actual or threatened death, serious injury, sexual violation, or other harm to one’s physical integrity. Researchers also may refer to complex exposures, or experiences that involve both threat and deprivation, which happen in many cases.

Early childhood is a sensitive period in human development, during which the brain, especially the circuitry related to emotion, attention, self-control, and stress, is shaped by the interplay of genetic information in the child’s genes and their lived experiences. According to developmental and evolutionary theory, biological systems, such as the reward system, show considerable functional plasticity (adaptability) early in development, making them highly malleable in the face of changing environmental conditions (Meaney et al., 2010). As children grow, the biological and environmental factors that determine their development become increasingly intertwined. Thus, early adversity and later developmental health are linked through the structural and functional development of specific brain and nervous system circuits, from those dealing with executive function to those governing responses to stress. 

Take this study for example. One group of researchers, studying an area of the brain called the amygdala that is heavily involved in the experience of emotions, have identified a critical point in childhood development for the experience of adversity They found that healthy adults first exposed to early adversity between the ages of 3 and 7, which is an important period for amygdala development, show greater cortisol awakening response in the amygdala relative to those first exposed to early adversity before 3 or after 7 (Flaherty et al., 2006).

Adverase childhood experiences that influence children’s development typically do not only include one-time, dramatic events; the daily, repeated events in a child’s life are often much more important. It is the chronic, day-to-day exposure to maltreatment, poor parenting, and other adversities, rather than an individual, dramatic occurrence of abuse, which causes the most damage to developmental health. Also, prior research has shown that different types of adverse experiences frequently co-occur, and most individuals exposed to childhood adversity have experienced multiple adverse experiences (Finkelhor et al., 2007; McLaughlin et al., 2012).

Even though adverse childhood events occur early in life, victims’ reactions tend to be subsequently kept and reinforced through a series of differential exposures to stressful and risky social contexts. For example, cognitive theory (Beck, 1976; Young et al., 2003) and attachment theory (Bowlby, 1969) both posit that negative experiences in childhood are internalized and continue to shape how the child responds to external events as they age. Those with exposure to childhood adversity and negative circumstances are more likely to continue to be exposed to – and even be drawn towards – stressful events and circumstances (Pearlin, 1989). 

 The Impact of Early Childhood Adversity

Study suggested that there is a bilateral relationship between childhood adversity and impulsivity. Childhood maltreatment leads to an elevated risk of individual impulsivity, which, in turn, results in greater subsequent maltreatment (Gershoff et al., 2002; Vasta et al., 1982). To disentangle and break this vicious circle, we would first explore how childhood maltreatment impacts individuals’ life.

Maltreatment events during childhood have deleterious effects later in life, including impulsive decision-making. Impulsive decision-making (or impulsive choice) refers to decisions based on evaluation of potential outcomes (i.e., risks and rewards) and is associated with the tendency to favor more immediate rather than delayed rewards (Demons et al., 2016; Broos et al., 2012). Two types of tasks are frequently used to assess impulsive decision-making. One is the Delay Discounting Task (DDT), which measures impulsive decision-making as a participant’s tendency to choose smaller immediate rewards over larger delayed rewards. The other is the Balloon Analogue Risk Task (BART), which models real-world risk behavior through the conceptual frame of balancing the potential for reward versus loss (Lejuez et al., 2002). For example, Delay discounting task was applied in both humans (Levitt et al., 2021; Acheson et al., 2019) and rats (Brydges et al., 2015). Similar findings showed that subjects with early adverse experiences made worse performance. Euser et al. (2013) assessed event-related potentials during a modified version of the Ballon Analogue Risk Task in adolescents with a parental history of substance use disorders. The results showed that high-risk male adolescents made significantly more risky and faster decisions than did non-risk controls. 

The link between adversity experienced early in development and increased impulsivity and reward incentive salience has been demonstrated in both animals and humans (Chugani et al., 2001). In animal models, maternal separation and isolated rearing increase impulsivity and hyperactivity. Adult rodents who, as pups, were separated from their mother show greater impulsivity, sensitivity to rewards, and behavioral inflexibility compared to adults who were reared naturally (Hall et al., 1998; Lovic et al., 2011). In humans, exposure to adversity early in life is associated with heightened ADHD symptoms, including greater impulsivity and hyperactivity (Laucht et al., 2007).

Although the relation between childhood maltreatment and impulsive decision making is well-established, further explanation of how this occurs is still needed. There are some theories on the matter. Life-history theory posits that organisms strategically allocate resources to different events and circumstances across their life span (Belsky et al. 2012; Belsky et al. 1991; Del Giudice et al. 2011; Ellis et al. 2009). Since these resources are finite by nature, it is impossible to maximally devote them to all major life functions. Thus, there is a trade-off. Natural selection favors individuals who can arrange development and activities, in other words, allocate resources, in a way that optimizes the trade-off between life course and different ecological conditions (Belsky et al. 2012). These strategies exist on a fast-slow continuum. People who adopt slower strategies tend to have high expectations and are relatively risk-averse because they have to survive to realize their expectations. Thus, they are characterized by later reproductive development and behavior, preferences toward relatively stable pair bonds, higher quality parental investment, and fewer offspring. Conversely, people reared in a harsh environment usually adopt the fast strategy, which is high-risk, impulsive, and prioritizes immediate over delayed rewards (Del Giudice et al. 2011; Ellis et al., 2014). They have low expectations with regards to future resource availability and are relatively risk-prone because they have little to lose. However, it is also worth noting that whether impulsivity is adaptive in harsh environments depends on the nature of the early life environment to which a person has been exposed.