There they go again. Taiwan and their 'big data' publishing, yet again, some rather interesting population-based research trends derived from data from the National Health Insurance Research Database (NHIRD).
This time around it is the paper by Han-Cheng Wang and colleagues  and the hypothesis to evaluate the "association between group A streptococcal (GAS) infections and the risks of developing tic disorders, obsessive-compulsive disorder (OCD), and attention-deficit/hyperactivity disorder (ADHD)." For those in the know, the relationship between Strep infection and those neuropsychiatric labels brings us into the realm of PANDAS and PANS (and no, not the fluffy black-and-white kind of panda either).
Based on a not insignificant participant number - "2,596 patients and 25,960 controls" - researchers set about looking at under-18 year olds newly diagnosed with a GAS infection and their subsequent risk of receiving one or more of those neuropsychiatric labels.
Compared to controls, the incidence of neuropsychiatric disorder in the GAS group was higher (60.42 per 10,000 person-years vs. 49.32 per 10,000 person-years) particularly when it came to the presentation of a tic disorder. If said GAS infection was serious enough to put someone in hospital, the risk of neuropsychiatric disorder was even higher compared with than those who did not have a GAS infection. The authors conclude: "Our results confirmed an association between previous group A streptococcal infection and neuropsychiatric disorders."
Set within the growing research base suggesting that various infections can very much lead to behavioural outcomes (see here for another example) as well as physical ones, there is some interesting science still to be done on the hows and whys. Whether said infection meets us during the nine months that made us (see here) or some time after provides some intriguing insights on how timing and infection type might show differential effects for a person. The question of whether (a) we can prevent certain infections or (b) offset their primary effects via the use of agents affecting immune function or immune response perhaps represent some of the more important avenues for further investigations in this area.
 Wang HC. et al. Group A Streptococcal Infections Are Associated With Increased Risk of Pediatric Neuropsychiatric Disorders: A Taiwanese Population-Based Cohort Study. J Clin Psychiatry. 2016 Jul;77(7):e848-54.
Wang, H., Lau, C., Lin, C., Chang, A., & Kao, C. (2016). Group A Streptococcal Infections Are Associated With Increased Risk of Pediatric Neuropsychiatric Disorders The Journal of Clinical Psychiatry DOI: 10.4088/JCP.14m09728