Social Isolation in Adolescence Can Cause Habit-Like Behavior in Adulthood

Experiments done in mice have shown that social isolation in adolescence can lead to habit-like behaviors in adulthood as opposed to goal based behavior. Humans and rodents who experience early-life traumas or adversities appear to be prone to habit-based behaviors, often occurring at the expense of goal-oriented actions. Despite consistencies across species, how adversity, particularly during specific developmental periods, causes long-term behavioral biases remains unclear. Compounding this issue, many rodent investigations using social isolation to model adversity test mice or rats while they are isolated, making it difficult to dissociate the consequences of current versus developmental hardship. 
The researchers Elizabeth A Hinton, Dan C Li, Aylet G Allen and Shannon L Gourley have concluded that habit biases were associated with glucocorticoid insufficiency in adolescence, oligodendorcyte marker loss throughout cortico-striatal regions, and dendritic spine and synaptic marker excess in the adult orbiotfrontal cortex (OFC). 
Adolescence is a critical period during which social experience optimizes one’s ability to seek and attain goals later in life. Age-typical dendritic spine elimination appears to be an essential factor, and in its absence, organisms may defer to habit-based behaviors.

Source: https://www.eneuro.org/content/6/5/ENEURO.0318-19.2019