Substance abuse complicates loneliness by adding an additional layer of concern. Either habitual substance abuse like the use of marijuana or addictive substance abuse like nicotine or alcohol can be, but not necessarily, used to cover over a multitude of problems. Alcohol can be used as a tranquilizer that covers psychosis. Various substances can be used to dull feelings from physical pain to loneliness itself. Another problem with substance abuse is the power of the addiction or habit. Another level of complication with abused substances is the illusion of power or control. Emotions, thoughts and behavior are changed in various ways by the abused substances. But since the person administers the substance herself there is an illusion of being in control. Many of these same persons object strongly when prescribed a drug for medical reasons. Then not taking the drug is viewed as being in control.
Since abused substances hide the essential nature of the individual loneliness is inevitable. As long as the person presents himself through the haze of substance controlled behavior he will not connect with others.
I have been with friends when we all were drinking. There is a sense of togetherness, a belonging that feels close and intimate. I have also been with the same people when I was not drinking. Then the close intimate behavior is unmasked. When I listen with a clear mind, I hear monologues. Everyone is talking but not responding to each other. Each person is lost in his or her own thoughts even though they take turns talking and laugh together the comments miss each other.