Hormone treatments given to thousands of men with prostate cancer may double their risk of developing dementia, research suggests.
About 18,000 British men start taking hormone pills or having jabs every year – nearly 40 per cent of the 47,000 diagnosed with prostate cancer.
The drugs work by lowering levels of testosterone, which is normally harmless but in prostate cancer patients can drive the growth of tumours.
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The therapy is standard for those whose cancers have begun to spread and cannot be eliminated just by surgery or radiotherapy.
But a study of nearly 9,300 US patients found that men treated with hormones were more than twice as likely to develop Alzheimer’s and other forms of dementia within five years. The participants, with an average age of 67, had a 7.9 per cent chance of being diagnosed with dementia if they were on hormone treatments. Men not on them had only a 3.5 per cent risk.
Lead researcher Dr Nigam Shah, of Stanford University in California, said: ‘The risk is real, and depending on the prior dementia history of the patient, we may want to consider alternative treatment.’
Findings published in journal JAMA Oncology showed that men of 70 and older who had been on hormones for at least 12 months were most at risk.
Scientists suspect that hormone treatments affect dementia risk as testosterone protects brain cells.
When testosterone levels are driven down – reducing cancer risk – it may leave brain cells exposed, meaning dementia is more likely.
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The most common form of hormone therapy in the UK is a drug called goserelin, sold under brand name Zoladex, which is injected.
It interferes with signals from the brain that tell the testicles to make testosterone. The scientists urged prostate cancer patients receiving hormone therapy not to change treatment without medical advice.
Co-author Dr Kevin Nead, from the University of Pennsylvania, said: ‘I was surprised at how ubiquitous the effects on all types of dementia were, but I would definitely not alter clinical care based on our results.’ He said more research was needed to look at the link between hormone treatments and dementia and identify what kinds of patients may be most at risk. Male hormones are known to play a role in the health and growth of neurons, which may help explain the association, said the experts.
Dr Matthew Hobbs, deputy director of research at charity Prostate Cancer UK, said: ‘Hormone therapy is a highly effective treatment for prostate cancer and can keep the disease at bay for many years.
‘However, all prostate cancer treatments can result in side effects and so it’s vital that men speak with their consultant to weigh up the benefits and risks of all available treatments. Although this research suggests that there may be a link between hormone therapy and dementia, it’s very hard to draw clear-cut conclusions.
‘Men having treatment for prostate cancer are likely to be living with other health problems which may also increase their risk of dementia. No man should stop taking hormone therapy based on these findings.’
Dr Laura Phipps of Alzheimer’s Research UK, said: ‘Studies like this, which take advantage of the rich data held in medical records, can be very useful. We need to better understand the impact of sex hormones in the brain in diseases like Alzheimer’s.
‘Age is the biggest risk factor for dementia, with genetics and lifestyle also playing a role. The weight of current evidence suggests that eating a healthy and balanced diet, not smoking, staying mentally and physically active, and keeping weight and blood pressure in check can all contribute to maintaining a healthy brain as we age.’
Daily Mail