INFECTIOUS TRIGGERS OF PSYCHIATRIC SYMPTOMS
With mounting evidence, there is a growing appreciation in the scientific community of the ability of bacterial and viral infections to have profound effects on the brain and behavior. In March of 2019 in JAMA Psychiatry (see resources section below), a group of researchers studying Danish medical records for more than 1 million individuals reported that the risk of developing OCD in teenagers increased by a staggering 8-fold following an infection. As stated in an accompanying editorial, the recent studies demonstrate a definitive link of infections to psychiatric symptoms in children and “bring a sense of urgency to detailing the underlying mechanisms of this association, in particular, because of the possibility that these severe and occasionally permanent neuropsychiatric conditions might be rapidly recognized and treated by pharmacological compounds already in clinical use.”
PANDAS AND PANS
Two infection-triggered disorders, Pediatric Autoimmune Neuropsychiatric Disorder Associated with Streptococcal Infections (PANDAS) and Pediatric Acute-Onset Neuropsychiatric Syndrome (PANS), were only described in the past 20 years. For reasons not yet fully understood, some children experience an abrupt onset of obsessive-compulsive behaviors (OCD) and/or motor or vocal tics following infection. In addition, children may develop severe food restriction/anorexia, separation anxiety, frequent urination, deterioration of fine motor skills (often seen as deterioration in handwriting), trouble sleeping, and/or significant mood changes.
BIOLOGICAL BASIS OF NEUROIMMUNE DISORDERS
Although research into the biological basis of PANDAS is still in its infancy, evidence suggests that an aberrant immune response to the strep infection disrupts normal functioning of the basal ganglia, a region of the brain involved in emotion, cognition, and movement. Research and clinical experience has confirmed an immune response to infectious pathogens in the onset of a subset of cases of mental illness in children, defining a broader class of post-infectious neuroimmune disorders.
CRITICAL NEED FOR RESEARCH
There are currently no laboratory tests or biomarkers which aid in the diagnosis of these conditions. Many children are initially misdiagnosed as having a primary psychiatric illness, which in the best of cases delays access to proper treatment, and in the worst of cases prevents proper treatment entirely. Rigorous scientific study is needed to unravel the mystery of how infections can trigger these psychiatric symptoms given the potential implications for thousands of children. Understanding the biological mechanism will enable patients to be diagnosed definitively and allow the best therapeutic approaches to be identified.