Increased levels of hormone testosterone — male sex hormone — in women could cause a brain disorder that can lead to blindness, finds a new study.

The study, led by the University of Birmingham in Britain, showed that excess testosterone leads to Idiopathic Intracranial Hypertension (IIH) — high pressure in the brain — resulting in blindness and daily long-term headaches in women.

The findings showed that women with IIH had raised levels of testosterones compared to those with obesity and polycystic ovary syndrome (PCOS).

The hormones were also found to be increased in the brain fluid of women with IIH.

"These findings mark a key step forward. For the first time we have found a pattern of androgen dysregulation that is unique to IIH and potentially a driver of abnormal brain pressure in people with the condition," said Alex Sinclair, Researcher from the varsity.

"Taken together this provides the first evidence that IIH may be a manifestation of female androgen excess," Sinclair added.

Originally identified over 100 years ago, the cause of IIH has remained unknown yet, despite speculation about why more than 95 per cent of the total incidence is in women with obesity.

For the study, published in the journal JCI Insight, the team examined the levels of testosterone in blood and urine, as well as in brain fluid known as cerebrospinal fluid (CSF), in 55 women aged 18 to 45 years with IIH.

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They then compared the results with the levels observed in women with obesity of the same age and body mass index (BMI), as well as a cohort of women with polycystic ovary syndrome (PCOS).

PCOS is known to be associated with increased levels of specific types of androgens, which can cause excess hair and irregular periods. (IANS)