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Mental illness and its Types

A person with mental illness may have difficulty thinking and affect emotional state and behaviours.

What is a mental illness?

Mental illness is a general term that refers to a group of illnesses that significantly affects how a person feels, thinks, behaves, and interacts with other people.

Mental illnesses can be very difficult and draining to those experiencing them, as well as their families and friends. They can also be permanent, temporary, or irregular.

If you or your loved ones is suffering from mental illness or a crisis in your life, please consider calling Lifeline on 13 11 14, beyondblue on 1300 22 4636, or the Kids Helpline on 1800 55 1800.

Types of mental illnesses

Bipolar disorder


Bipolar disorder is a mental illness marked by extreme shifts in mood. Symptoms can include an extremely elevated mood called mania. They can also include episodes of depression. Bipolar disorder is also known as bipolar disease or manic depression.

People with bipolar disorder may have trouble managing everyday life tasks at school or work, or maintaining relationships. There’s no cure, but there are many treatment options available that can help to manage the symptoms.

When episodes are extreme, some people may experience suicidal thoughts and symptoms of psychosis. A person may be affected so much that they are unable to distinguish reality from fantasy (Better Health).

The causes of bipolar disorder are not fully understood but are likely to be a combination of genetics and other causes.

Depression is a mental illness which significantly affects the way someone feels, causing a persistent lowering of their mood and feelings of dejection and loss.

While we all feel sad, moody or low from time to time, some people experience these feelings intensely, for long periods of time (weeks, months or even years) and sometimes without any apparent reason. Depression is more than just a low mood – it's a serious condition that affects your physical and mental health.

While the exact cause of depression isn’t known, it is generally due to a combination of recent events, personal factors, family history, drug and alcohol use, as well as changes within the brain itself.

Anxiety disorders

An anxiety disorder is a medical condition characterised by persistent, excessive worry.


Anxiety disorders can take a number of forms. Common to all of these is anxiety so distressing it can interfere with a person’s ability to carry out, or take pleasure in, day-to-day life.

Examples of anxiety disorders include generalised anxiety disorder, social anxiety disorder (social phobia) and specific phobias (Mayo Clinic).

Other symptoms of anxiety disorders can include panic attacks, trembling, sweating, difficulty breathing, feeling faint, rapid heartbeat, nausea, or avoiding certain situations.

Some of the causes or triggers of anxiety include the environment, stressful situations, trauma, family history, and substance abuse.



Schizophrenia is a psychosis, a type of mental illness characterized by distortions in thinking, perception, emotions, language, sense of self and behaviour.

If not receiving treatment, people with schizophrenia may experience persistent symptoms of psychosis.

They can have hallucinations such as seeing things, hearing voices, smelling odours, and feeling sensations on the skin. They can also have delusions which are false beliefs that strongly persist in their mind, and refuse to go away.

Other signs and symptoms can include low motivation, dulled emotions, rambling and disorganised speech, lack of desire to form social relationships, and a lack of ability to express emotion.


Schizophrenia is associated with considerable disability and may affect educational and occupational performance.

People with schizophrenia are 2 - 3 times more likely to die early than the general population (2). This is often due to physical illnesses, such as cardiovascular, metabolic and infectious diseases.


Anorexia nervosa

Bulimia nervosa

Anorexia nervosa is a psychological illness that has devastating physical consequences. It is characterised by low body weight and body image distortion with an obsessive fear of gaining weight, which manifests itself through depriving the body of food. It often coincides with increased levels of exercise.

People who have anorexia can restrict their eating, compulsively exercise, and misuse laxatives or diet aids. It’s important to know that this behaviour is not connected to vanity or a lifestyle choice in any way.

Anorexia has one of the highest mortality rates of all mental illnesses, with 10-20% of people dying within 20 years from complications or suicide.

Bulimia nervosa is a serious psychiatric illness characterised by recurrent binge-eating episodes (the consumption of abnormally large amounts of food in a short period of time), immediately followed by self-induced vomiting, fasting, over-exercising and/or the misuse of laxatives, enemas or diuretics.

The cycle of binge eating and purging/exercising, leads to intense feelings of guilt and shame for the person. This mental illness often goes undetected because those with bulimia are normal weight or slightly overweight, and they often hide the behaviours associated.

Obsessive compulsive disorder (OCD)

Obsessive compulsive disorder (OCD) is an anxiety disorder that affects two to three percent of the population (more than 500,000 Australians). It usually begins in late childhood or early adolescence. People with OCD experience recurrent and persistent thoughts, images or impulses that are intrusive and unwanted (obsessions). 

Some common obsessions include:

  • Fear of germs, dirt, and poisons

  • Fear of harm to yourself or others

  • Excessive concern with symmetry and orderliness

  • Hoarding, or saving and collecting things

Some common compulsions can include:

  • Excessive checking of items associated with safety such as locks and appliances

  • Excessive cleaning, washing, and showering

  • Touching, tapping or moving in a particular way or a number of times

  • Repeating words or numbers a certain number of times


Post-traumatic stress disorder (PTSD)

Impulse control disorder (ICD) and addiction

Post-traumatic stress disorder (PTSD) is a particular set of reactions that can develop in people who have been through a traumatic event which threatened their life or safety, or that of others around them. This could be a car or other serious accident, physical or sexual assault, war or torture, or disasters such as bushfires or floods. As a result, the person experiences feelings of intense fear, helplessness or horror.

Other symptoms include sleeping difficulties, lack of concentration, being easily startled, being constantly on the look out for danger, avoiding reminders of the event, and feeling emotionally numb.

Impulse control disorder (ICD) is a class of disorders characterised by impulsivity and being unable to resist temptation which may harm oneself or others.

Impulse control disorders (ICDs) are characterized by urges and behaviours that are excessive and/or harmful to oneself or others and cause significant impairment in social and occupational functioning, as well as legal and financial difficulties. ICDs are relatively common psychiatric conditions, yet are poorly understood by the general public, clinicians, and individuals struggling with the disorder.

Addiction and substance abuse can be of a variety of legal and illegal substances such as alcohol, drugs, gambling, prescription medicines (pain killers or sedatives), inhalants such as household cleaners, and even internet usage. When someone becomes dependent, they can experience cravings or withdrawal symptoms when they stop.

Body dysmorphic disorder

Body dysmorphic disorder is a mental health disorder in which you can't stop thinking about one or more perceived defects or flaws in your appearance — a flaw that appears minor or can't be seen by others. But you may feel so embarrassed, ashamed and anxious that you may avoid many social situations.

These perceived flaws cause the person substantial distress, and this obsession impacts their daily life. People often obsess over their appearance and body image, repeatedly check the mirror, groom themselves obsessively, constantly diet, over exercise, and seek reassurance.

It’s not uncommon for people to seek out numerous cosmetic procedures to try to ‘fix’ the perceived flaws, but are never satisfied.

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