Psychopathy is defined as a mental (antisocial) disorder in which an individual manifests amoral and antisocial behavior, shows a lack of ability to love or establish meaningful personal relationships, expresses extreme egocentricity, and demonstrates a failure to learn from experience and other behaviors associated with the condition.

What percentage of people are psychopaths?

Psychopathy is observed in about 1% of the population, is much more prevalent in men than women, and affects about 15–25% of the prison population.



Psychopaths have reduced connections between the ventromedial prefrontal cortex (vmPFC), the part of the brain responsible for sentiments such as empathy and guilt, and the amygdala, which mediates fear and anxiety.

The brains of people who have psychopathic tendencies show less emotional response to images of people being hurt. 

The emotional parts of their brains have fewer connections too hence they don’t consciously “feel” for others.

Source: The Human Brain Book, Rita Carter
In a study, it’s found that psychopaths have reduced volumes of gray matter in the brain called paralimbic system (the brain region responsible for emotion regulation and self-control) hence, these people lack empathy.

Other Factors to Developing Psychopathy


There is no “psychopathy gene” but studies tell that psychopathy tends to run in families. Parents may carry one of more genetic variants that increase their child’s chance of developing psychopathy.


Not experiencing warmth and responsive parenting in early childhood; as well as perinatal factors such as smoking, high stress levels during pregnancy, and birth complications can have an impact to developing psychopathy in people

Brain Injury

Traumatic brain injury such as damage to the ventromedial prefrontal cortex show remarkable signs similar to diagnosed psychopathic individuals like reduced response to emotional stimuli


Commonly used tests for psychopathy are the following:

Psychopathy Checklist-Revised (PCL-R)

The PCL-R is a 20-item inventory most commonly used to assess whether an individual exhibits certain traits and behaviors that could indicate psychopathy. It’s intended to be completed along with a semi-structured interview and a review of available records, such as police reports or medical information

Psychopathic Personality Inventory (PPL)

This test is used to assess psychopathic traits in non-criminal populations. It may still be used with incarcerated individuals, but it is more often applied to other populations, such as university students.

Triarchic Psychopathy Measure (TriPM):

This test is a 58-item, self-report assessment that measures psychopathy within the three traits identified in the triarchic model: boldness, meanness, and disinhibition. Each trait is measured on separate subscales and added up in resulting in a total psychopathy score.

How Psychopathy Affects Life

List of criminal psychopaths:

John Gacy​

A Des Plaines, Illinois contractor and Junior Chamber of Commerce, “Man of the Year” who entertained children as “Pogo the Clown” murdered thirty-two young men in the 1970s, burying most of the bodies in the crawl space under his house

Richard Ramirez​

A Satan-worshipping serial killer known as “Night Stalker” who proudly described himself as “evil” and convicted with thirteen murders and thirty other felonies, robbery, burglary, rape, and attempted murder

Source: With Conscience, The Disturbing World of the Psychopaths Among Us by Robert Hare

Clifford Olson​

A Canadian serial murderer who persuaded the government to pay him $100,00 to show the authorities where he buried his young victims, does everything he can to remain in the spotlight

But some individuals can also develop into successful psychopaths


Psychopathy is a personality disorder, not a mental illness. There is no cure for psychopaths, and they will never be able to change.

They can only be managed with reward-based treatment, but it’s simply a means of control rather than cure ​

There are no pharmacological therapies known to have been trialed for alleviating the emotional, interpersonal, and moral deficits of psychopathy​

One technique called the Decompression Model involving a reward of every positive, pro-social behavior an individual demonstrate can only help shape behavior – but could not treat psychopathy ​

Other Useful Videos and Articles

Inside the brains of Psychopaths

Are Psychopaths Born or Created? Nature and Biology of Psychopathy

10 Subtle Signs of a Psychopath

Can Neuroscience help us eradicate psychopathy?

What working with Psychopaths taught me about leadership - TEDxStavanger

Real-Life Psychopaths aren’t so smart