Pathological lying doesn’t have a single cause. It arises from a combination of brain structure differences, personality traits, underlying mental health conditions, and learned behavioral patterns. Unlike ordinary lying, which people do for clear practical reasons, pathological lying is persistent, often disproportionate to any obvious benefit, and can feel automatic to the person doing it.
Brain Differences in Pathological Liars
One of the most striking findings comes from brain imaging research. A study published in The British Journal of Psychiatry found that people identified as pathological liars had significantly more white matter in several regions of the prefrontal cortex, the area of the brain responsible for planning, decision-making, and social behavior. Specifically, white matter volume was 22 to 26 percent higher in the orbitofrontal cortex, 28 to 32 percent higher in the middle frontal cortex, and 32 to 36 percent higher in the inferior frontal cortex compared to both antisocial individuals who didn’t lie pathologically and people with no antisocial traits at all.
White matter is the wiring that connects different brain regions. More of it in the prefrontal cortex may make it easier to link ideas, craft narratives, and juggle the cognitive demands of deception, essentially giving pathological liars a brain that’s structurally better equipped for complex lying. Notably, gray matter volume (the tissue that handles processing and judgment) showed no difference between groups. This suggests the issue isn’t a lack of processing power but rather an overconnected network that may lower the mental effort required to fabricate stories.
Personality Disorders and Pathological Lying
Pathological lying frequently appears alongside cluster B personality disorders: borderline, antisocial, and narcissistic personality disorder. Each drives lying for different reasons.
- Borderline personality disorder: Lying often functions as a coping mechanism for feelings of inadequacy. People with this condition may fabricate stories to maintain relationships or avoid the abandonment they deeply fear.
- Narcissistic personality disorder: The lies tend to center on exaggerating accomplishments, status, or importance. The underlying motivation is a need for admiration and validation from others.
- Antisocial personality disorder: Deception here is typically more calculated, used for personal gain or to manipulate people. Lying may feel like a natural tool rather than something that requires justification.
Not everyone who lies pathologically has a personality disorder, but the overlap is substantial enough that clinicians evaluating chronic lying will typically look for these conditions as part of the picture.
Internal Rewards and the “High” of Deception
One of the defining features of pathological lying is that the lies often seem pointless to an outside observer. The person isn’t avoiding punishment or gaining money. Instead, the reward is internal. Some pathological liars experience something similar to a high when they successfully deceive someone, comparable to the rush seen in other compulsive behaviors. The gratification may come from feeling clever, from controlling how others perceive them, or from inhabiting a more exciting version of their life.
Research distinguishes between internally and externally motivated lies. Externally motivated lies respond to outside pressure, threats, or tangible rewards like money. Internally motivated lies are driven by the person’s own desires for reputation, attention, or amusement, and sometimes they’re told for no discernible reason at all. Pathological lying falls heavily into this internal category, which is part of what makes it so confusing to the people around the liar.
Compulsive Lying vs. Pathological Lying
These terms are often used interchangeably, but some clinicians draw a useful distinction. Compulsive lying is characterized by an uncontrollable habit of fabricating stories, often without a clear motive. The person may genuinely struggle to tell the truth even when they want to, and the lying has an addictive quality to it.
Pathological lying, by contrast, typically involves some degree of motive, whether it’s seeking attention, admiration, pity, or assistance. The lies tend to blend truth and falsehood in ways that make them harder to detect, and they can serve as tools of manipulation. In practice, many people who lie chronically show features of both patterns, and the line between them is blurry enough that even mental health professionals debate it.
Why It’s Hard to Diagnose
Pathological lying is not recognized as a standalone diagnosis in the current psychiatric classification system. It doesn’t have its own entry in the DSM-5-TR, the manual clinicians use to diagnose mental health conditions. Instead, it’s treated as a feature or symptom of other disorders, most commonly the cluster B personality disorders described above.
This creates a real problem. Because there’s no formal diagnosis, there are no systematic studies on how common it is in the general population, no validated screening tools, and no research-tested treatments. Clinicians who work with pathological liars are essentially improvising based on clinical experience and treatments borrowed from related conditions.
How Pathological Lying Is Treated
Most mental health professionals who treat pathological lying lean toward cognitive behavioral therapy, which helps people identify the thoughts and situations that trigger lying and develop alternative responses. In a survey of psychotherapists, 73 percent recommended CBT as part of treatment. Other approaches included dialectical behavioral therapy, behavioral techniques like habit reversal training (which treats lying as a behavioral pattern that can be interrupted and replaced), and group therapy, which provides accountability and social feedback.
The honest challenge is that nobody knows how well these treatments work for pathological lying specifically. As one researcher with the American Psychological Association put it, without a formal diagnosis, there are no research-based treatments to evaluate. Clinicians tend to be optimistic about the possibility of change, but the evidence base simply doesn’t exist yet. When pathological lying occurs alongside a personality disorder, treating the underlying condition often reduces the lying as well, which is currently the most practical path forward.
What Drives It in Everyday Life
If you’re trying to understand why someone in your life lies pathologically, the causes are rarely simple. The behavior usually reflects some combination of a brain that makes deception cognitively easy, personality traits that reward attention-seeking or manipulation, emotional needs that the person doesn’t know how to meet honestly, and years of reinforcement where lying worked. Many pathological liars started lying heavily in adolescence or early adulthood, and the behavior became so ingrained that it feels automatic rather than deliberate.
Some pathological liars are fully aware they’re lying and choose to continue. Others seem to partially believe their own fabrications, especially when they’ve told the same story repeatedly. This self-deception can make the behavior especially resistant to change, because the person may not experience their lies as lies in the way an outside observer would.