High hormone levels may cause a brain condition that can lead to blindness in women, reported researchers from the University of Birmingham.

Idiopathic intracranial hypertension (IIH) is caused by high pressure in the brain resulting in vision loss and incapacitating, daily, long-term headaches.

The Birmingham study explored the role of androgens (a type of hormone) in IIH. Androgen levels in blood, urine and cerebrospinal fluid (CSF) were tested in 55 women with IIH aged between 18 to 45 and compared with levels in obese women of the same age and body mass index (BMI) and a cohort of women with polycystic ovary syndrome (PCOS) where increased levels of androgens are typical. Researchers found IIH patients had a very different profile of raised androgen levels. Most notably, the high level of the androgen testosterone in the blood and, crucially, in the CSF of IIH women.

When the researchers analysed human choroidal plexus tissue where CSF is produced, they confirmed androgens could increase the rate of CSF secretion. Senior author, Dr Alex Sinclair, said, “For the first time we have found a pattern of androgen dysregulation unique to IIH and potentially a driver of abnormal brain pressure in people with the condition. This provides the first evidence IIH may be a manifestation of female androgen excess.”

IIH was originally identified more than 100 years ago and despite speculation about why more than 95% occurs in obese women, the exact cause is still not known. The incidence of IIH has increased 150% in the last 10 years, in line with the global rise in obesity, but current treatment options remain limited. The Birmingham study was released soon after a group of specialists in neurology, neurosurgery, neuroradiology and ophthalmology, with expertise in managing IIH, released the first international collaborative guidelines to try to improve IIH diagnosis and treatment.