Narcissistic personality disorder (NPD) is a personality condition. Such people show exaggerated feelings of self-importance. They find it difficult to show empathy and love to other people. They want to be admired by others and need to gain power and success.
Cluster B personality disorders are also known as “dramatic” personality disorders. Common to these is very emotional behaviour which creates problems in relationships. Studies have found that around 1-6% of the general population suffer from narcissistic personality disorder. It is usually found in men.
Before the introduction of narcissistic personality disorder, the term narcissism was used to explain a person’s extreme self-love and self-admiration. The word narcissism comes from Greek mythology. A handsome young man named Narcissus saw his own reflection in a pool of water and fell in love with himself. Narcissus’ love could not be returned back and therefore he became a flower, which was named after him. 
In 1925 Robert Waelder introduced the term narcissistic personality and by 1968 the term narcissistic personality disorder was used by Heinz Kohut.
People with NPD feel very confident in their self and in what they are able to do and achieve and think that they are the best in everything. They need to be admired by people around them and are obsessed with fantasies of power, beauty and talent. They consider themselves unique and special and believe that they should be treated differently. They find it difficult to care for and show empathy to others and therefore struggle to keep stable relationships and show love or interest in anyone else. An obvious symptom of NPD is arrogant and impatient behaviour and attitude. These traits make it difficult for people suffering from narcissistic personality disorder to ask for clinical help as they often do not understand they need to do so.
According to the DSM-5 narcissistic characteristics are often seen in successful people, but an individual can be diagnosed with NPD only when these traits affect their every day life by making it harder.
People with NPD often also have additional psychological disorders such as depression, bipolar disorder and substance abuse, as well as other disorders from the second cluster of personality disorders. 
Narcissistic personality disorder can take many forms. These are the three general categories and their descriptions:
– Grandiose narcissists: likely to take advantage of others and ignore their well-being and emotions
– Shy narcissists: tend to feel both better and worse than people around them, narcissistic traits act as a defence strategy when they don’t feel “enough”.
– High-functioning narcissists: are competitive and look for attention, they are flirty and energetic 
A clear cause for the narcissistic personality disorder has not yet been found. As with many mental conditions, it is believed that NPD is a result of both nature and nurture. Studies have suggested that there is 45-80% heritability, meaning that these traits are passed on from a parent to a child, supporting the genetic cause of the disorder. This means that traits that have to do with sensitivity, aggression and low levels of anxiety can be passed down to a child from a family member.
Other studies support the role of the environment in the development of NPD, meaning that the way a child grew up can play a role in having NPD as an adult later on in life. One theory thinks that having a distant and cold parent could lead to the child developing NPD. A different theory focuses again on parenting style but supports that a child can develop NPD if the parents are treating the child as very “special” and “unique”. Other recent theories believe that a traumatic bad experience when a child is young can cause narcissistic traits and symptoms to develop.
Finally, from a neurological view, studies have found that NPD is connected to a “problem” in the brain, making it hard to express and control emotions such as empathy.