Stability of psychological symptoms: drug use consequences and intervening processes.

We integrate aspects of coping response, impaired ability, and motivational explanations for the causes and consequences of drug abuse, all which were cast previously as competing or alternative paradigms. We projected a model of 1) continual daily drug use as a consequence of early adolescent psychological symptoms and 2) continual daily drug use as an influential variable in maintaining or exacerbating these symptoms over the young adult life-course. Gender, race, and education also were modeled explicitly according to their presumed theoretical importance. Finally, we modeled contemporaneous factors such as physical health and employment status as the common consequences of the shared independent variables in order to reduce bias in the estimated structural relationships. We found that continual daily drug use is significantly dependent on early psychopathology and increases psychological symptoms significantly. Daily proximate drug use has direct negative effects on education. Education, in turn, improves both mental and physical symptoms significantly. During young adulthood, psychological symptoms are related significantly to contemporaneous unemployment and physical health limitations; thus modeling these symptoms as common consequences reduces potentially biased estimates of the effect of shared independent variables.