# Indirect causal relationship

An indirect causal relationship is said to exist if one condition has an effect upon an intermediary factor that, in turn, increases the likelihood of developing the second condition [38]. For example, research has shown that the presence of early onset AOD use reduces the likelihood of completing high school, entering tertiary education, and completing tertiary education [39, 40]. This poor level of education may lead to later life difficulties (e.g., unemployment) that may lead to other problems, such as depression [38]. Similarly, the reverse is possible, whereby a depressive disorder may lead to difficulties in completing study and work commitments, which may in turn lead to difficulties finding employment, increasing the risk of AOD misuse [41-43].