Yes, and the main reason would be that creative people are getting more mental stress, compared to the normal type of person. It is a very sad thing when losing talented artists because of drugs and alcohol addictions. Hopefully, talented artists will realize that addictions only brings disaster and they will not take that route.
Psychologists often see artistic work as a healthy conversion of strong emotions. While this sometimes results in great masterpieces, all too often the process fails, leaving the artist unable and unequipped to handle their feelings. In our society, the most common method of dealing with strong feelings is self-medication through the use of recreational substances, both legal and illegal. The temporary relief provided is frequently a simple gateway to addiction disguised as relief.
Artists and musicians tend to be very emotional and sensitive, and this can create barriers to dealing with life's problems effectively. It is very common for them to deal with their pain through the use of alcohol and/or drugs rather than suffer. The same sensitivity that makes their art powerful can also be a source of difficulty when it comes to having a thick skin or coping with stress.
According to studies ten percent of Americans suffer from alcohol or drug addiction and only ten or eleven percent (depending on what study you read) seek treatment. Addiction has no social-economic preference. It will go after someone that is in Yale or in jail.
The only difference between people that are in the public spotlight and regular people is that the media follows their every move. Because of this it is harder to seek treatment anonymously.