A symptom is something the patient senses and depicts, while a sign is something other individuals, for example, the specialist take notice of. For example, drowsiness could be an indicator, but enlarged pupils are clues.
Substance dependence is when someone is addicted to a something like drugs or alcohol and they are not able to control their use of the substance. He/she continues to use it, despite the fact that it may be harmful (the person may or may not be aware of the possible risk).
Drug addiction can lead to strong cravings. It's possible that the addict wants to stop taking the substance but finds it really hard to do so on his or her own.
The clues and indicators that someone is addicted differ from one person to the other, depend on the drug, the genes of the individual and status in life.
The clues and indicators of addiction could be that:
Some people who abuse drugs or alcohol might not be technically addicted but can still suffer the effects mentioned here but do not usually suffer from withdrawal symptoms or have the same obsession to use the substance.