2. Assumptions about causes: Same as physical illness  Brain anatomy  Infection  Neurotransmitters/Chemical imbalance  Genetics

3. Chemical imbalance too high too low  Levels of chemicals in brain too high or too low  These chemicals transmit signals between nerves  Chemicals called neurotransmitters

4. Vesicles release neurotransmitter into synaptic cleft psychlotron.org.uk

5. Neurotransmitter binds to receptors & activates them psychlotron.org.uk

6. Enzymes are released to break down the neurotransmitter psychlotron.org.uk

7. Excess neurotransmitter is taken up by the pre-synaptic neuron psychlotron.org.uk

8. Vesicles are replenished with new & reused neurotransmitter psychlotron.org.uk

9. Chemical imbalance neurotransmitters  Levels of neurotransmitters may be too high or too low serotonin  Depression- too low serotonin dopamine  Schizophrenia – too high dopamine

10. Infection  Bacteria and viruses may lead to mental disorders  streptococcus infection has been linked to OCD in some children  glandular feveranorexia  glandular fever linked to anorexia  (only 4 patients)  Today Show Saving Sammy PANDAS - YouTube Today Show Saving Sammy PANDAS - YouTube

11. Neuroanatomy  Damage to brain structures birthinjury  May be abnormal from birth or due to injury hypothalamus  E.g. hypothalamus role in eating disorders  Ventricles and schizophenia Evidence Evidence:  In mice if hypothalamus cut they either starve or overeat

12. Mouse lesion hypothalamus

14. Schizophrenic twins

15. Genes DNA  inherit a tendency for mental disorders in DNA from parents  Tested using:  Family studies e.g. schizophrenia 18x more likely if 1 st degree relative with it  Twin studies  Twin studies e.g. Comparing MZ (identical) & DZ twins  Concordance rates (both have disorder)  Anorexia MZ 56%, DZ 7%  Bipolar disorder MZ= 80%, DZ= 16%  Gene Found At The Root of Hair-Pulling Disorder - YouTube Gene Found At The Root of Hair-Pulling Disorder - YouTube