Using magnetic resonance imaging (MRI), scientists from the National Neuroscience Institute (NNI) found lesions and plaque build-up in parts of the brain which control short-term memory, and the part that links the right brain to the left.

The damages were caused by severe low blood sugar, a result of the illegal drug that had been contaminated by glibenclamide, which is used to treat high sugar in diabetic patients.

Severe low blood sugar can lead to coma and death, if left untreated.

Of the eight patients in the study, seven were found to have damages in the forebrain that controls short-term memory and spatial navigation and three had unusual damage in one side of the brain.

The findings is published in this month's Radiology, a peer review journal and represents one of the largest series of hypoglycaemic brain damage in the world.

Hypoglycaemic brain damage or brain damage resulting from severely low blood sugar is a rare condition.

Illegal sex enhancement pills have killed 10 men here in the past seven months.

The 10, aged between 35 and 84, were comatose when they died from complications such as infections and major organ failure.

A check with the Health Science Authority (HSA) found more than 220 patients who had indulged in illegal sex enhancement pills.