Final answer:
Physical drug dependence involves physiological need and withdrawal symptoms, leading to tolerance and potentially overdose. Psychological drug dependence is characterized by the emotional need to use the drug to relieve distress. Addiction represents the compulsive use of the drug despite negative consequences.
Step-by-step explanation:
Physical drug dependence is the physiological need for a drug that causes unpleasant withdrawal symptoms and a craving for the drug when it is discontinued. This involves changes in normal bodily functions, and the user will experience withdrawal upon cessation of use. Physical dependence can lead to tolerance, where the person requires more of the drug to achieve the previously experienced effects. This increasing use can become dangerous and lead to overdose and death.
Whereas psychological drug dependence is the strong desire to repeat the use of a drug for emotional reasons. A person with psychological dependence may use the drug to relieve psychological distress, such as anxiety or depression, rather than because of a physical need for the drug.
Drug addiction may follow as the compulsive use of a psychoactive substance in spite of the negative consequences. Over time, increasing amounts of the drug may be needed to obtain the desired effect, which can also lead to an increased risk of overdose and death.