The etiology of idiopathic intracranial hypertension (IIH) remains largely unknown; however, this vision-threatening condition is most common among young obese women, which may link changes in gut microbiota to the development of metabolic disorders such as IIH. A recent study sought to compare the gut microbial populations of obese patients with and without IIH, demonstrating that the two microbial ecosystems are in fact distinct.

To determine how microbiota composition could possibly be correlated to IIH in affected patients, researchers included 45 women in their study: 25 IIH patients and 20 healthy controls. According to the BMI classification used, were three subjects of normal weight (BMI 18.5-25), 13 overweight (BMI 25-30), 12 obese Class I (BMI 30-35), eight obese Class II (BMI 35-40) and nine obese Class III (BMI over 40). Using feces samples from each participant, taxonomic data for bacteria and archaea were collected.

Compared with healthy individuals, IIH patients were found to have less variety of health-promoting bacterial species including Lactobacillus ruminis (L. ruminis), Atopobium parvulum, Megamonas hypermegale, Ruminococcus gnavus, MEL.A1 and Streptococcus sp. I-G2. The researchers also discovered that those treated with acetazolamide had more Lactobacillus brevis, another beneficial bacterium.

“In each of the lower BMI groups, S. thermophilus was found higher among the patients compared with the controls,” the researchers wrote in their paper. “S. thermophilus was shown to possess many beneficial health effects in humans, such as improving gut inflammation, possessing antimutagenic and antitumorigenic effects, lactose digestion in lactose intolerant individuals, stimulation of the immune system and more. Intriguingly, a recent study demonstrated a significant reduction in body weight and BMI following the ingestion of probiotic bacteria such as S. thermophilus, Lactobacillus acidophilus, Bifidobacterium infantis, Bifidobacterium breve, and Enterococcus faecalis,” they wrote. Previous research has also found that a 6% weight reduction can improve a patient’s papilledema. 

Understanding the many roles of gut bacteria could help determine which bacterial groups could be used to improve IIH patients’ overall health and reduce their BMI. Acetazolamide, as referenced above, may be helpful in treating IIH patients by encouraging the growth of beneficial bacterium. 

Berkowitz E, Kopelman Y, Kadosh D, et al. “More guts than brains?”–the role of gut microbiota in idiopathic intracranial hypertension. J Neuro-Ophthalmol 2021;00:1-8.