In certain situations the Social Security Administration will approve or deny a claim where there is substance abuse involved. The first thing Social Security will determine is if the substance abuse is a contributing factor to the disability. Essentially, this means that they will determine if the substance abuse makes the alleged conditions worse, or perhaps even caused the alleged condition. If it is determined that it is a contributing factor then SSA will take the stand point that if the substance abuse stopped, the medical condition would not be as severe therefore, denying the benefits.
On the other hand, what happens if the substance abuse is definitely the cause of the medical condition? For example: You have been diagnosed with cirrhosis of the liver with a history of alcohol abuse. The alcohol abuse has been determined to be the cause of the medical condition but you have not drunk in numerous years. SSA will not hold it against you for the reason the medical condition began, as you are no longer drinking, and no matter what, the damage is so severe that it has no affect if you are still currently drinking or not, as the damage can not be reversed.
Therefore, it can be very confusing if your substance abuse will prevent you from receiving benefits or not, especially if you are suffering from a mental health condition. Speaking with someone knowledgeable in this area can help answer all these important questions for you.