The biological basis of mental illness

Mental illness is, in part, an illness of the brain. Learning about the brain can:

• give information from a biological and medical perspective (and some idea of its complexity)
• help you understand and support treatment
• assist you in dealing with the stigmas of mental illness
• support the realisation that no one is to blame for the onset of mental illness.

About brain research

A lot of what the community commonly thinks and knows about mental illness is based on previous experience and social stigma. It is often information that is out of date and leaves us with an impression of hopelessness. In fact:

• Over half of what we know about the brain in relation to mental illness we have learnt in the last 10 years. As a consequence, medications and treatments have improved significantly and people who are now being diagnosed with mental illness have a better prognosis than people diagnosed before that time.
• New imaging technology allows the brain to be examined while the person is experiencing mental illness, whereas before we relied on autopsy information.
• Research indicates that physical changes commonly occur within the brain in mental illness.
• The brain pathways responsible for ‘higher’ mental functioning (feeling emotions, interpreting information)
  are affected.
• The linking of an illness to particular changes in the brain is extremely difficult. (Brain scanning techniques
  are used alongside assessment of behaviour and symptoms.)
• Brain research has already achieved much, and has further capacity to improve medications and other physical treatments.

What changes in the brain when mental illness is present?

Like other body parts, the brain is susceptible to injury and change. Both the chemical messaging system and the physical structures of the brain can be altered in mental illness.

The chemical, or neurotransmission system in the brain

Neurons

The brain is made up of billions of cells called neurons.

Each neuron is a link in a chain and can have thousands of connections to other neurons.

These connections of neurons form chains through which messages are relayed in the brain.

Synapses

The synapse is the meeting point of two neurons. A signal must be transmitted from one neuron across the synapse to the other neuron. These events occur within milliseconds.

Neurotransmitters

• Neurotransmitters are the chemicals that conduct the messages across the synapse.
• When a signal arrives at the end of a neuron, the neurotransmitter spills into the gap and crosses the gap.
• Scientists have identified over 50 neurotransmitters that are messengers communicating information from one part of the brain to another, and to all parts of the body.
• From this simple system, complicated brains are built. And this system seems affected in many mental illnesses.

Neurotransmitter malfunctions can occur because there is:

• not enough neurotransmitter
• too much neurotransmitter
• malabsorption of the neurotransmitter.

Some important neurotransmitters and their roles are:

• dopamine: activation level, mood, movement
• norepinephrine: mood, activation level
• serotonin: mood, sleep, appetite, aggression
• acetylcholine: mood, autonomic nervous system.

Malfunction in these neurotransmitters is found in many forms of mental illness. It is possible that, in biologically vulnerable individuals, high stress levels ‘trigger’ malfunctioning in neurotransmitters (e.g. production of neurotransmitters cannot keep up with the body’s demands or the neurotransmitters are not effectively removed from the system).

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