Paediatric acute-onset neuropsychiatric syndrome (PANS) is a perplexing condition that causes children to develop severe psychiatric symptoms seemingly overnight, transforming happy, healthy youngsters into children struggling with obsessive thoughts, restrictive eating, and dramatic behavioral changes that can leave families searching desperately for answers.
Understanding PANS: A Sudden Change in Children
Paediatric acute-onset neuropsychiatric syndrome, known as PANS, describes a clinical condition where children experience an unusually abrupt onset of severe mental health symptoms. The hallmark of this syndrome is how quickly it appears—often within 72 hours or less. One week a child may be functioning normally at home and school, participating in activities, and socializing with friends. The next week, that same child might be consumed by obsessive thoughts they cannot control or suddenly refusing to eat, accompanied by other distressing symptoms that seem to emerge from nowhere.[1][3]
The condition is defined by the sudden appearance of obsessive-compulsive symptoms (intrusive, unwanted thoughts that lead to repetitive behaviors) or severely restricted food intake, along with at least two other acute behavioral, cognitive, or neurological symptoms. These additional symptoms can include severe anxiety, mood swings, sleep disturbances, changes in handwriting, difficulty concentrating, urinary problems, or sensory sensitivities. The symptoms typically follow a pattern of flare-ups and periods of relative calm, known as a relapsing-remitting course, where acute episodes alternate with times when symptoms lessen.[3][7][9]
Stanford University established the first academic institution program dedicated to PANS in 2012, recognizing the need for specialized, multidisciplinary care for affected children and their families. The program was created to provide comprehensive care while conducting groundbreaking research to better understand this challenging condition.[1]
PANDAS: A Specific Type of PANS
PANDAS, which stands for Pediatric Autoimmune Neuropsychiatric Disorders Associated with Streptococcal Infections, is considered a subset of PANS. This term was first described by researchers at the National Institute of Mental Health in 1998, more than a decade before the broader PANS category was established. The discovery came after scientists observed five children who all developed sudden-onset obsessive-compulsive disorder and tics (involuntary, purposeless movements) after being diagnosed with strep throat caused by Group A streptococcus bacteria.[4][8]
PANDAS has five specific diagnostic criteria. First, the child must have obsessive-compulsive disorder or tics, particularly multiple, complex, or unusual tics. Second, there is an age requirement—symptoms must first appear between the ages of 3 years and puberty. Third, the symptoms must have an acute onset and follow an episodic course, with relapses and remissions. Fourth, there must be a temporal association with a Group A streptococcal infection, meaning the symptoms appear around the time of a strep infection. Finally, the child shows neurological abnormalities such as unusual movements.[5][13]
The key difference between PANS and PANDAS is the trigger. PANDAS specifically requires evidence of a strep infection, whereas PANS does not require any particular trigger to be identified. Both conditions cause similar symptoms that appear suddenly, but PANDAS is thought to be linked specifically to streptococcal bacteria, while PANS may result from other infections such as Lyme disease, influenza, Mycoplasma pneumonia, or upper respiratory infections. Some cases of PANS may also be triggered by metabolic disturbances, other inflammatory reactions, or psychological trauma, though not all cases have a clear identifiable trigger.[4][5][9]
How Common Is PANS?
Research indicates that PANS is considered a rare condition, though the exact prevalence remains uncertain. Most reported cases occur in children between the ages of 3 and 12 years, with the average age of onset around 6 to 7 years for PANDAS cases specifically. Some healthcare providers believe the condition may be more common in boys, though this pattern is not definitively established.[4][5]
The rarity of PANS, combined with its dramatic and sometimes frightening presentation, means that many families struggle to find healthcare providers who are familiar with the condition. Parents often spend significant time researching online, desperately seeking specialists who understand what they are experiencing. The lack of widespread awareness about PANS can lead to delayed diagnosis and treatment, adding to the distress families experience.[18]
It appears to be very uncommon for teenagers or adults to develop mental or neurological symptoms following strep infections, though some researchers are investigating potential long-term effects of these illnesses. The condition primarily affects prepubescent children, and the symptoms typically have a pre-pubescent onset.[4][9]
What Causes PANS and PANDAS?
The underlying cause of PANS is believed to involve immune-mediated processes, though the exact mechanisms are not fully understood. The prevailing theory suggests that the central nervous system is affected by immune responses triggered by various pathogens—organisms such as bacteria or viruses that cause disease. In more than 80 percent of well-characterized PANS patient groups, evidence of post-infectious autoimmunity or neuroinflammation (inflammation affecting the brain and nervous system) has been found.[3][10]
For PANDAS specifically, some researchers believe the condition occurs when a child’s immune system produces antibodies (protective proteins) to fight the bacteria causing a strep infection. However, these antibodies may mistakenly attack healthy cells in other tissues because those cells structurally resemble the strep bacteria—a phenomenon called molecular mimicry. When these misdirected antibodies affect brain tissue, they may lead to the psychological and neurological symptoms observed in affected children.[4]
PANS symptoms are thought to result from brain changes secondary to inflammation triggered by infections, metabolic disturbances, other inflammatory reactions, and potentially psychological trauma. Expert opinions increasingly view PANS as the effect of post-infectious events or stressors leading to what can be described as brain inflammation, similar to what occurs in anti-neuronal psychosis and other autoimmune conditions affecting the brain.[3][9]
The question of why some children develop PANDAS after a Group A strep infection while others do not remains unanswered. Several hypotheses have been proposed. One possibility involves strain differences—there are over 150 strains of Group A streptococci, and only 10 to 12 of these cause acute rheumatic fever and Sydenham’s chorea, which serve as medical models for PANDAS. It is reasonable to hypothesize that only certain bacterial strains trigger PANS or PANDAS symptoms. Geographic clusters of new cases have been reported, which supports this theory.[5]
Genetic vulnerability may also play a role. Potential defects in clearing Group A strep infections, resolving inflammation after infection, differences in brain circuitry, variations in how cells respond to immune signals in the brain, or abnormal expression of molecules involved in nerve signaling during infection are all hypothesized to contribute to neuroimmune disorders including PANS and PANDAS. However, no specific genetic marker has been identified to date.[5]
Risk Factors for Developing PANS and PANDAS
Children who have frequent Group A streptococcal infections, such as repeated cases of strep throat or scarlet fever, may be at higher risk of developing PANDAS. A family history of autoimmune diseases or rheumatic fever also appears to increase risk, suggesting a genetic component to susceptibility.[4]
The location of the strep infection may matter. While strep throat infections are the most common trigger reported for PANDAS, cases have also occurred following perianal strep infections (strep affecting the area around the anus). Strep infections can occur in the throat, tonsils, and anus, and each area should be examined and tested when PANDAS is suspected. Animal research suggests that strep bacteria in the nasal cavity may potentially access or influence immune cells in the brain through pathways along nerves, providing another possible route for infection to trigger symptoms.[5]
Importantly, strep bacteria that produce post-infectious complications like PANDAS often do not cause typical symptoms such as sore throat, fever, or abdominal pain. This means infections can go undetected and untreated for prolonged periods, potentially allowing the immune response that triggers PANS symptoms to develop. A child can have PANDAS even without obvious evidence of a preceding strep infection, particularly if the infection was not symptomatic or if the child was exposed to someone else with strep.[5]
Recognizing the Symptoms of PANS
The symptoms of PANS vary widely from child to child and can involve a combination of psychological and neurological manifestations. What makes PANS distinctive is the sudden, dramatic onset of these symptoms and their tendency to occur in episodes that last for days or weeks before subsiding and potentially returning.[4][6]
Psychological symptoms that have been reported in children with PANS include severe anxiety or depression that was not previously present. Children may experience bedwetting even if they were previously toilet-trained. Dramatic changes in mood or personality are common, including sudden rage or irritability that seems out of character. Difficulty sleeping, whether trouble falling asleep or staying asleep, frequently occurs. Some children develop a disinterest in food or severely restrictive eating patterns that can resemble an eating disorder. Fidgeting and symptoms similar to attention-deficit/hyperactivity disorder may appear. Obsessive-compulsive behaviors become prominent, with children performing repetitive actions or experiencing intrusive thoughts they cannot control. Severe separation anxiety may develop, making it difficult for children to be away from their primary caregiver. Tics similar to those seen in Tourette syndrome, such as repeated blinking, head movements, or vocalizations, may emerge.[4][8]
Neurological symptoms associated with PANS include changes in motor skills, particularly problems with handwriting that parents and teachers may notice suddenly. Children may have difficulty concentrating or learning, with schoolwork becoming significantly more challenging. Poor performance in school often follows, even in previously high-achieving students. Reduced coordination may make physical activities more difficult. Some children develop heightened sensitivity to light and sound, finding normal environmental stimuli overwhelming.[4]
Additional symptoms described in the PANS diagnostic criteria include behavioral regression, where a child seems to lose previously acquired skills or maturity. Sudden deterioration in school performance extends beyond just concentration difficulties to encompass overall academic functioning. Mood disorders manifest as irritability, aggression, or severe oppositional behaviors. Urinary symptoms such as increased frequency of urination may occur. Sensory amplification or motor abnormalities, including tics and difficulty with handwriting (called dysgraphia), are common. Various physical signs may appear, particularly sleep disturbances that disrupt normal rest patterns.[5][13]
Children experiencing these symptoms may beg their parents for help, desperately seeking relief from the mental anguish they cannot understand or control. Some children scream in terror, feeling trapped by thoughts or fears that exist only in their minds. Parents describe being unable to comfort their child with hugs or reassurance that previously would have helped. The child who was once comforted by parental presence may become inconsolable, unable to accept the support offered to them.[18]
Preventing PANS and PANDAS
Because the exact mechanisms that trigger PANS remain unclear, specific prevention strategies are limited. However, for PANDAS specifically, preventing or promptly treating streptococcal infections may help reduce risk. This means taking children to a healthcare provider when they develop symptoms of strep throat, such as sore throat with fever, and completing the full course of antibiotics if prescribed. Ensuring that family members with strep infections receive appropriate treatment can reduce household exposure.[5]
Some children with PANDAS may benefit from antibiotic prophylaxis, which means taking antibiotics regularly to prevent new infections. However, this approach should only be undertaken under medical supervision and is not appropriate for all children. The decision to use preventive antibiotics depends on individual circumstances, including the frequency of infections and severity of symptoms.[10][13]
Testing household contacts and treating any identified strep carriers can help reduce a child’s exposure to the bacteria. Perianal, throat, and tonsil areas should all be cultured when screening for strep in family members. Good hygiene practices, including regular handwashing and avoiding sharing eating utensils or drinking cups, can reduce transmission of infections in general.[5]
Beyond infection prevention, maintaining overall health through adequate sleep, nutritious diet, and stress management may support immune system function, though no specific dietary or lifestyle interventions have been proven to prevent PANS.[8]
How PANS Affects the Body: Pathophysiology
PANS is understood as a condition where the central nervous system—the brain and spinal cord—experiences dysfunction due to immune-mediated inflammation. The pathophysiology involves complex interactions between the immune system and neurological tissues. When a child encounters an infection or other trigger, their immune system mounts a response. In susceptible individuals, this immune response may inadvertently target brain tissue, leading to inflammation that disrupts normal brain function.[3]
Research has identified brain abnormalities in children with PANS using neuroimaging techniques. These brain changes suggest that inflammation affects specific regions involved in behavior, emotion, and movement control. The inflammation may alter how nerve cells communicate with each other, disrupting the delicate balance of neurotransmitters—chemical messengers that allow brain cells to send signals. When this communication system is disturbed, the behavioral and cognitive symptoms of PANS emerge.[1][3]
The immune-mediated nature of PANS means that the body’s defense system, which normally protects against disease, becomes dysregulated. Abnormal activation of the immune system may lead to production of antibodies or immune cells that attack neuronal cells—the specialized cells that make up the nervous system. This autoimmune process, where the body attacks its own healthy tissues, creates ongoing inflammation that manifests as psychiatric and neurological symptoms.[5][10]
Studies examining cerebrospinal fluid and blood from children with PANS have found evidence supporting immune system involvement and inflammation. Genetic factors may influence how a child’s immune system responds to infections, potentially explaining why some children develop PANS while others with similar infections do not. Differences in how the immune system clears infections, resolves inflammation, or regulates immune responses in the brain may all contribute to disease susceptibility.[3][5]
The relapsing-remitting course typical of PANS suggests that inflammation waxes and wanes over time. During acute flares, inflammatory processes intensify, leading to severe symptoms. During periods of remission, inflammation subsides, and symptoms improve or resolve. This pattern mirrors other immune-mediated conditions and supports the theory that ongoing immune dysregulation drives the disease process.[9]
Interestingly, when comparing PANS to other conditions like autoimmune encephalitis, Sydenham’s chorea, or even traditional psychiatric disorders such as obsessive-compulsive disorder and Tourette syndrome, researchers have found more similarities than differences. This overlap suggests that PANS may represent part of a broader spectrum of neuroimmune conditions rather than a completely distinct disease entity.[3]