Alcohol

Alcohol releases inhibitions, and can lead to violent and impulsive behaviour, which is particularly dangerous for those who are already suffering from mood problems.  Consumption of alcohol remains implicated in nearly all behavioural and health problems experienced by young adults, including sexual aggression, impaired academic performance, vandalism and fighting, sexually transmitted diseases and motor vehicle accidents and fatalities. 

As one might expect, harmful consequences of drinking rise in proportion to the amount of alcohol consumed.  Excessive consumption of alcohol leads to loss of coordination, concentration, and memory, and in some cases to complete memory blackouts.  Alcohol abuse can also facilitate self-harm and suicide.