Describing addiction: physical and psychological dependence, tolerance and…

The idea

Addiction is a disorder in which someone keeps using a substance, or repeating a behaviour, despite knowing what it costs them. Physical dependence is a bodily adaptation: the nervous system has recalibrated around the drug, so stopping it throws the body out of balance and produces withdrawal, a cluster of symptoms usually opposite in direction to the drug’s own effects. Stopping nicotine brings irritability, anxiety and craving that peak at 24 to 72 hours. Psychological dependence is the compulsion side, the craving and the sense of not coping without it. Tolerance is why the dose climbs: repeated use downregulates receptors, so the same amount does less than it used to. Evaluate the split, because it leaks. Gambling involves no ingested chemical yet produces craving and withdrawal-like symptoms, which is why DSM-5 (2013) moved gambling disorder in with the substance disorders.

What earns the marks

• Physical dependence: the body has adapted to the substance, so its absence produces a physiological withdrawal state and use continues partly to avoid that state.
• Psychological dependence: a compulsion to experience the effect again, shown in craving, preoccupation and the belief that one cannot function without it.
• Tolerance: a reduced response to the same dose after repeated use, explained by receptor downregulation, so the user escalates the amount to get the original effect.
• Withdrawal syndrome: symptoms appearing on cessation or reduction, typically the opposite of the drug’s acute effects (a stimulant leaves fatigue and low mood).
• Named illustration: nicotine withdrawal produces irritability, anxiety, poor concentration and craving, peaking within roughly 24 to 72 hours of the last cigarette.

Common mistakes and how to put them right

• Treating tolerance and dependence as the same thing.

  Put it right: Tolerance is a shrinking response to a given dose; dependence is needing the substance to feel or function normally, and an examiner wants them separated.

• Describing withdrawal as simply "feeling ill" or "wanting it badly".

  Put it right: Credit comes from naming symptoms and noting they typically oppose the drug’s own effects, not from vague discomfort.

• Equating addiction with heavy use.

  Put it right: Someone can drink a great deal without tolerance, withdrawal or loss of control, and the term describes the pattern of dependence rather than the quantity.

• Claiming behavioural addictions such as gambling are "only psychological" and therefore not real addiction, which ignores the DSM-5 reclassification and the physiological craving evidence.

Exam tips

• In a "distinguish between" question, define both terms and then supply one contrasting example each. The mark is for the contrast, so an answer defining only the first term caps itself.
• Given a scenario, quote the stem back: if the person "needs three cans to feel what one used to do" that is tolerance, and if they are "shaky and irritable by lunchtime" that is withdrawal. Labelling the evidence is where the AO2 marks sit.
• Do not spend an evaluation paragraph listing symptoms. AO3 here is the argument that the physical/psychological boundary is blurred, with gambling as the worked case.