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

BIOLOGICAL APPROACH

Assumptions about causes:Same as physical illness

Brain anatomy

Infection Neurotransmitters/Chemical

imbalance Genetics

Chemical imbalance

Levels of chemicals in brain too high or too low

These chemicals transmit signals between nerves

Chemicals called neurotransmitters

Vesicles release neurotransmitter into synaptic cleft

psyc

hlot

ron.

org.

uk

Neurotransmitter binds to receptors & activates them

psyc

hlot

ron.

org.

uk

Enzymes are released to break down the neurotransmitter

psyc

hlot

ron.

org.

uk

Excess neurotransmitter is taken up by the pre-synaptic neuron

psyc

hlot

ron.

org.

uk

Vesicles are replenished with new & reused neurotransmitter

psyc

hlot

ron.

org.

uk

Chemical imbalance

Levels of neurotransmitters may be too high or too low

Depression- too low serotonin Schizophrenia – too high dopamine

Infection

Bacteria and viruses may lead to mental disorders

streptococcus infection has been linked to OCD in some children

glandular fever linked to anorexia (only 4 patients) Today Show Saving Sammy PANDAS -

YouTube

Neuroanatomy Damage to brain structures May be abnormal from birth or due to injury E.g. hypothalamus role in eating disorders Ventricles and schizopheniaEvidence: In mice if hypothalamus cut they either

starve or overeat

Mouse lesion hypothalamus

Schizophrenic twins

Genes inherit a tendency for mental disorders in

DNA from parents Tested using: Family studies e.g. schizophrenia 18x more

likely if 1st degree relative with it 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