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Understanding

Brain and behaviour · 2 min read

Why addiction affects behaviour

Many families say the person they love seems to have changed. They may be unreliable, secretive, irritable or unkind. Understanding why can help you respond with clarity, while still protecting yourself.

Published 13 October 2026

Cravings and priorities

As addiction develops, getting and using a substance can start to take priority over other things, including relationships and responsibilities.

Withdrawal and mood

The effects of using, and of coming down or withdrawing, can cause irritability, anxiety, low mood or aggression.

Shame and secrecy

Many people feel deeply ashamed of their use. Shame can drive secrecy and defensiveness, which in turn damages trust.

The person is still there

Addiction can mask parts of someone's personality, but many families find that the person they know is still present, and may become more visible again during recovery.

Key considerations

  • Explaining behaviour is not the same as excusing it.
  • You don't have to accept abuse or harm in any circumstances.
  • If you feel unsafe, contact specialist support.

Suggested next steps

  • Read 'Navigating dishonesty and broken trust'.
  • Set a boundary that protects your wellbeing.
  • Talk to a family support group.

Further reading from trusted sources