Animation: depression

View this animation to see the changes that happen in your brain if you have depression.

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The brain is made up of billions of nerve cells that provide overall control of how you think, feel, make decisions and move.

These nerve cells are called called neurons. They transmit signals through the body, including the brain, by connecting with each other across junctions called synapses.

These signals are transmitted across the synapse via chemical messengers called neurotransmitters.

  • An electrical impulse carries the signal down the sending neuron to the end, where neurotransmitters are released into the synapse.
  • When the concentration of neurotransmitters in the synapse reaches a certain level, they start to bind to receptors on the end of the receiving neuron.
  • This generates the impulse that allows the electrical signal to be passed down the receiving neuron.
  • Afterwards, the neurotransmitters are reabsorbed back into the sending neuron.

In people with depression, communication between the nerve cells does not occur as it should. The reasons for this are varied:

  • depressed brains may not produce as much serotonin as normal brains;
  • the receptors on the receiving neuron may not have the same affinity for serotonin as those in a normal brain;
  • the brain may not be as efficient in reabsorbing the serotonin back into the sending neuron; or
  • the serotonin may be reabsorbed back into the sending neuron too quickly, before it can bind to the receptors.

While chemical changes in the brain are an important part of the picture of depression, genetic and environmental factors also come into play.

Factors that can contribute to depression include:

  • Family history
  • Stress
  • Chronic illness
  • Pessimistic outlook and low self-esteem
  • Financial problems
  • Alcohol abuse
  • Hormones
  • Some medicines
  • Recently having given birth

If you think you may be depressed, seek help from your doctor or a mental health professional. There are medicines and treatments available that can help people with depression and which can cut short episodes of depression. The earlier you seek help, the sooner you will start to feel better.

If you have feelings of wanting to harm yourself or of suicide, please contact a doctor, mental health professional or telephone helpline immediately.

National Helplines
If you or someone you know is depressed and/or having suicidal thoughts, see your doctor, or phone one of these helplines.
Lifeline (24 hours)13 11 14
Kids Helpline (under 18 years of age)1800 55 1800
Just Ask - rural mental health information1300 13 11 14
Mensline Australia (24 hours)1300 78 99 78
SANE Helpline - mental illness information, support and referral1800 18 SANE (7263)


1. Black Dog Institute [website]. Depression � causes of depression: Biochemical (updated 2009, Sep 28). Available at: (accessed 2010, Jun 22)
2. Black Dog Institute [website]. Biochemical causes of depression. Available at: (accessed 2010, Jun 22)
3. Beyondblue [website]. Depression � what puts a person at risk? (updated 2009, May 25). Available at: (accessed 2010, Jun 22)
4. Mayo Clinic [website]. Video: Antidepressants � how they help relieve depression (updated 2008, Dec 6). Available at: (accessed 2010, Jun 28)
5. McKenzie K. Treating depression. In: Ames D, Arnold P, editors. The Australian Medical Association (AMA) Home Medical Guide to Depression Sydney: Dorling Kindersley; 2001. p. 19, 57-59.