"Individuals hospitalized with acute mania have a markedly increased rate of bacterial infections, as evidenced by the recent prescription of antimicrobial agents. The prevention and effective treatment of bacterial infections may be important interventions for the management of individuals with mania."
That was the research bottom-line reported by Robert Yolken and colleagues  (yes, that Robert Yolken) who continued a theme of how immune function/response might be something pretty important when it comes to all-things psychiatry and in particular, when it comes to diagnoses like mania (see here). Some media interest in this work can be seen here.
On this occasion, the name of the game was to investigate "whether individuals hospitalized with acute mania have evidence of bacterial infections as determined by the prescription of systemic antimicrobial agents." Antimicrobial agents normally means antibiotics; evidence of their use was searched for in over 230 people "hospitalized for acute mania in either an inpatient unit or a day hospital" compared with some 550 controls.
Researchers reported that among their cohort there was "a substantially increased rate of recent antimicrobial prescription, defined as exposure within three days of ascertainment." 'Substantial' in this respect meant 18 of 234 hospitalised people (~7%) compared with 7 of 555 controls (~1%). Interestingly, authors also reported that the site of bacterial infection for which antimicrobials were given was most commonly urinary tract infection for women "while the respiratory tract and mucosal surfaces were the most common sites in men." Mention of the the urinary tract as a source of infection brought me back to another post a while back (see here) and some intriguing data about urinary tract infection and risk of acute psychosis.
This latest Yolken data further add to the growing body of research suggesting that either cause or effect, the immune system does seem to be associated with various behavioural and psychiatric labels. My reading of this work suggests that the authors favour the idea that the infection itself (or response to infection) might be the more important aspect to any relationship but I'm not so sure that things are so straight-forward. Indeed, on the other occasions where I've talked about infection and psychiatry, the use of antibiotics - particularly recurrent prescriptions of antibiotics - might not be without possible side-effects (see here) in certain contexts.
There is more to do in this area, not least with regards to possible mechanisms of effect and whether the "prevention and effective treatment of bacterial infections may be important interventions for the management of individuals with mania." I would also hope that given the 'when you swallow a grenade' sentiments associated with antimicrobial use, the trillions of wee beasties that call us home (the gut microbiota) might also figure in any future research strategy.
 Yolken R. et al. Individuals hospitalized with acute mania have increased exposure to antimicrobial medications. Bipolar Disorders. 2016. 17 July.
Yolken R, Adamos M, Katsafanas E, Khushalani S, Origoni A, Savage C, Schweinfurth L, Stallings C, Sweeney K, & Dickerson F (2016). Individuals hospitalized with acute mania have increased exposure to antimicrobial medications. Bipolar disorders PMID: 27425597