Drug and alcohol addiction can lead to a number of dangerous long-term health consequences. Many people know that these types of substances can lead to short-term physical health issues like respiratory depression and liver problems, and can lead to overdoses and death. However, there are many mental effects of using drugs and alcohol that are not discussed as often. Some of these substances can lead to problematic mental health problems. And there is evidence that even after reaching sobriety, these problems may persist.