What Causes Paranoia? What Current Research Says About Paranoid Thoughts

Medically reviewed by Corey Pitts, MA, LCMHC, LCAS, CCS
Updated October 16, 2024by BetterHelp Editorial Team

Paranoia can be linked to a number of mental health disorders and to possible changes in brain structure and chemicals. Knowing more about paranoia and ways to address paranoid thought patterns could help people who are living in this elevated state of anxiety and fear. 

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What is paranoia?

According to the American Psychological Association, paranoia involves thoughts or behaviors “relating to or exhibiting extreme distrust or suspiciousness.” Paranoid thinking can make someone believe that other people are intentionally trying to hurt them, manipulate them, exploit them, or deceive them, even when they don’t have evidence to support these beliefs. Persistent paranoid thoughts can cause significant disruption in various aspects of functioning and well-being. 

Paranoid personality disorder

Paranoia can be associated with a number of mental health conditions, but its primary association with mental illness is with paranoid personality disorder (PPD). PPD is a personality disorder characterized by long-term patterns of distrust and suspicion of others, typically in ways that negatively impact personal connections. Paranoid personality disorder can result in avoidance of vulnerability and closeness with other people, often leading to social isolation. Since social connections are closely linked to overall health, PPD can have a serious impact on an individual's well-being.

Mental health impacts of paranoid personality disorder

More specific mental health effects of paranoid personality disorder can include:

  • A lack of interest in healthy relationships
  • An inability to trust other people
  • Social isolation
  • Loneliness
  • Depression
  • Anxiety
  • Development of other symptoms of certain mental health conditions, like obsessive-compulsive behaviors
  • Distrust of institutions, such as government, education, healthcare, etc.
  • Development of other personality disorders

Possible causes of paranoia

It’s not known exactly what causes paranoia in the brain, but there is some evidence that multiple factors can come into play. Learning more about them can help you understand how this symptom might come about.

The influence of brain structure on paranoia

Some evidence suggests that differences in the parts of the brain most closely associated with fear, self-protection, and threat detection and evasion may contribute to the development of paranoid thinking patterns. The amygdala—the part of the brain known as the “fear center,” responsible for the body’s fight-or-flight response—may be more easily activated in people with tendencies towards paranoia, potentially resulting in perceiving threats where none exist.

Increased amygdala activity can combine with lower activity in the prefrontal cortex to produce paranoid thinking. The prefrontal cortex is responsible for helping us make decisions and use logic and reason—abilities that may not be as prominent in people with paranoia, as they may tend to have trouble rationally assessing situations.   

Neurotransmitters and brain chemistry

Neurotransmitters are chemicals in the brain that act as “messengers” between neurons, or brain cells. People with paranoia may have higher concentrations of certain neurotransmitters. 

Dopamine, one of the brain’s so-called “feel good” chemicals, can be closely associated not just with the brain’s reward system, but with a person’s perception of reality. High levels of dopamine can cause distortions in how a person sees the world around them, which may contribute to paranoia. 

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The brain’s response to stress

Stress—particularly when chronic—can have a range of negative impacts on both the body and the brain. It activates the fight-or-flight response, which can heighten overall alertness and potentially predispose someone towards thought patterns that focus on fear. Chronic stress could lead the brain to start assessing every situation in terms of threat level, which could make everyday interactions seem menacing and cause paranoia to develop. 

The relationship between trauma and paranoia

Traumatic experiences can cause changes in the way the brain processes and responds to emotions and codes and stores memories. These changes could lead to hypervigilance, in which a person remains in a constant state of tension, ready to react to potential danger. Over time, hypervigilance can nurture patterns of paranoid thinking. Distrust and suspiciousness may also be more common in trauma survivors, as these attitudes may be a protective strategy. 

If you are experiencing trauma, support is available. Please see our Get Help Now page for more resources.

Other mental health conditions that can involve paranoia

Paranoia can sometimes be a symptom of an underlying mental health condition besides a personality disorder. Some of these conditions include: 

  • Post-traumatic stress disorder (PTSD): As mentioned above, traumatic experiences can lead to paranoia as a defense mechanism. People with PTSD may be more prone to regarding those around them with an elevated level of suspicion.
  • Substance use disorders: Any disorder involving a person regularly misusing a mind-altering substance could lead to changes in the brain that may make paranoia more likely. Stimulants, particularly methamphetamine, may have a higher probability of such effects according to the Substance Abuse and Mental Health Services Administration (SAMHSA).
  • Bipolar disorder: The manic episodes associated with some types of this mental health condition can lead to elevated levels of paranoia—particularly a belief that one is being watched or followed.
  • Schizophrenia: Historically, the schizophrenia diagnosis was divided into subcategories, one of which was referred to as “paranoid schizophrenia.” Now, paranoid delusions are considered a common symptom of the singular disorder of schizophrenia. 
  • Delusional disorder: With delusional disorder, a person experiences delusions, or beliefs that are not rooted in reality and that they can’t be reasoned out of. Persecutory delusions, or the belief that one is going to be harmed, can result in paranoia. 

Mental health effects of paranoia

Paranoia can lead to a sense of isolation, which may eventually evolve into self-loathing and hopelessness. These feelings can lead to the development of other mental health conditions, like depression, anxiety, and substance use disorders. 

Physical health effects of paranoia

Paranoia may cause mental strain and stress, which can lead to a number of physical health consequences—particularly when left unmanaged or untreated over the long term. Some of these include:

  • High blood pressure
  • An increased risk of heart attacks and stroke
  • Cardiovascular concerns
  • Sleep disturbances
  • Weight gain or loss
  • A weakened immune system
  • Fatigue
  • Unexplained aches and pains
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How to find support for paranoia

Paranoia can be debilitating in a number of ways, but help is available. A mental health specialist can provide the treatment options that may be right for your particular situation and needs. Meeting with a therapist for a mental health screening and treatment advice is often a recommended first step for those experiencing symptoms like paranoia.

That said, paranoia may sometimes manifest as a distrust of healthcare providers, potentially leading some people to avoid any sort of medical treatment. Online therapy could be a method of meeting with a mental health professional in a lower-pressure environment, which may help alleviate some fears associated with paranoia. 

Research indicates that online therapy may be as effective as traditional in-person therapy in many cases when it comes to addressing a number of mental health concerns, including paranoia. For example, one study suggests that completing a course of online therapy specifically intended to address paranoid thoughts helped to reduce those thought patterns

Takeaway

Neurologically, the exact cause of paranoia is unknown, but differences in brain structure and neurotransmitter levels are thought to play a role. This symptom is also associated with various mental health concerns and substance use. If you’re experiencing paranoia, meeting with a healthcare provider is usually recommended to determine the underlying cause and get support.
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