Depression coupled with substance abuse is called 'dual diagnosis'. Research has established that nearly half of the people addicted to alcohol or/and drugs have an overlapping mental disorder. Depression, drugs and alcohol are coherently related. Some people might resort to drugs and alcohol to seek relief from depression (called self-medication) while others might contract depression as a result of substance abuse. It is like a vicious circle and it can get extremely arduous to break away from it.
In most simple terms depression occurs when the brain produces less serotonin and norepinephrine, alcohol further reduces these chemicals, hence a person suffering from depression should stay away from it. Once the intoxication fades away you will be left feeling all the more blue and depressed. Alcohol literally boosts the depression symptoms increasing both their recurrence and asperity. About 40% people who drink heavily have this mental disorder. Depressed people my briefly experience exhilaration however it's soon replaced by irritability, fatigue, disarray and they may even pass-out totally oblivious of their surroundings.
Just like alcohol, drugs can be used as a form of self medication. Depression can set in because of the addiction or as a withdrawal symptom when a person tries to rid himself of the menace. Vice versa, an addict can get depression as one of the many adverse effects that drugs have. Drug addiction often leads to a lot of distress, one is likely to have trouble with law and in relationships, hence an addict aggravates his depression by isolating himself from the society. Also, a lot of money goes into supporting an addiction, so more often than not a person gets into huge financial losses.
Depression is curable in all forms even when a person indulges in substance abuse. It just gets a little more difficult as an addict has to cope with both the withdrawal symptoms and his mental condition. It is imperative to seek help from quarters let your loved ones know of your problems and ask for their support, visit a doctor and give him a complete account of your addiction and depression symptoms. Many support groups also help people fight both these problems, join them. Most importantly resolve to give yourself a better life devoid of substance abuse and depression.