5457367049_8fb6a84f41_zA blood test that can detect early signs of dementia – good news, surely?   When I saw the recent reports I hoped it was, but knowing how these things work – and being a cynical cove – I wondered about the upbeat certainty of many of the headlines.

These are the facts.  Researchers from Georgetown University Medical Centre in America examined 525 healthy participants aged 70 and over and monitored them for five years.  Their research, published in the journal Nature Medicine, identified molecules in blood that could be used to predict with 90 per cent accuracy whether people will go on to develop mild cognitive impairment or Alzheimer’s.

I know a little about dementia.  My mum suffered (and I’m afraid in her case, that word is accurate) from three different forms of it in the last 10 years of her life, but I’m not a medic and have limited knowledge of the science of the condition.

The first worrying fact to jump out at me was the 90 per cent accuracy rate.  Even with my shaky maths I knew this meant that 10 per cent of those tested could get a false positive result – they could be told that they were going to develop the condition when they weren’t, or vice versa.

And of course, there is no cure for Alzheimer’s.  Medical screening for an incurable condition raises thorny ethical issues.

I decided to garner reactions to the news from those far better qualified than me, including several people now living with different dementias.

When she was 12, Beth Britton’s father developed vascular dementia, which he lived with for 19 years before passing away in 2012.  During that time Beth cared for him and since his death she has become one of the UK’s leading campaigners on the condition.

Her reaction to the blood test announcement was characteristically thoughtful.  First, she highlighted the confusion in many people’s minds between dementia and Alzheimer’s.

“Many people do not understand that Alzheimer’s is only one form of dementia. So anyone taking this test, should it ever come to market, will need to fully understand that even if it shows as negative for Alzheimer’s, that doesn’t mean that they won’t develop another form of dementia in the future”.

How clear, and true.   She goes on to describe a greater flaw in the patina of good news.  “Moreover, if the test cannot distinguish between Mild Cognitive Impairment and Alzheimer’s that is quite worrying. Mild Cognitive Impairment is not a form of dementia and may never lead to a form of dementia. This could be very misleading for patients”.

Having read the reports, Beth concluded that she wouldn’t take the blood test in its current form, or advise any of her family to do so.  Coming from someone with her knowledge of the subject and close personal connections to it, her carefully worded advice is not to be ignored.

But what of those currently living with dementia – would they be tempted to have such a test?

Chris Roberts is in his 50s and has Alzheimer’s.  He qualified his response to me with the words, “Sorry, I’m not very intellectual these days, my learning and memory are pretty basic”.  His comments were anything but – and showed exactly why the maxim “no decision about me without me” is so important.

Chris may not be completely au fait with the details of the proposed screening but he made the very valid point that an earlier understanding of unusual actions could help relationships, “and even save marriages”.   Chris knows the nitty-gritty of living with dementia – the stresses it places on everyday life.  “If nothing else, it (a test) would enable understanding and support could then be put into place”.

The word “inspirational” is overused.  In Kate Swaffer’s case, it’s spot on.   This 50-something woman lives in Australia, is intelligent and forthright.  Six years ago she was diagnosed with dementia.

Without knowing the details and limitations of the test, Kate said she’d possibly have had it and, had it shown she was at risk, she would have focused on her brain and body health.  As for medical announcements in general, she says she gets ticked off with them and believes nothing should be reported until human trials are in progress, while recognising that this may impact funding.

An academic expert in frontotemporal dementia, Shibley Rahman produced a forensic analysis of the week’s news in his blog, “The truth behind *that* blood test for Alzheimer’s”.  Some of his more complex arguments were beyond my grasp, but his overall message is clear.  We need to consider such reports with caution.

He questions, among other things, the reliability of the diagnoses of the different conditions that go on to cause dementia (a crucial aspect of the research) and, using expert citations, concludes that the wrong diagnosis is given in 20-30 per cent of cases.   So, for Shibley, the very basis of the research has a high rate of inaccuracy.

He explains that the blood tests are not routine ones, but “specialist assays” with subsequent and considerable cost implications.  And, like Beth Britton, he is worried by the misleading conflation of Alzheimer’s and Mild Cognitive Impairment – and by the often overlooked fact that there is not one dementia and therefore not one cure-all, but hundreds of varieties of the condition, each requiring different treatments (and diagnoses).

So, what has my very unscientific survey revealed?

First, that I was right to be wary of the story.  Journalism, it is said, is the first rough draft of history – and we would do well to remember that.

But I return to Chris Roberts, who has dementia.  At least they are trying, he said. “And any research is better than none, obviously”.   He may say his intellectual powers are not what they were, but to me he’s expressed the nub of the issue.

The fact that research into the various dementias is happening, being reported on so that it can be talked about, analysed, queried and criticised, by you and me, by Kate, Chris, Shibley and Beth, by journalists (medical and otherwise), in broadcast and print news, on Twitter and Facebook, is good.

All research, by its very nature, is a slow, incremental progression towards a stated end, with helpful advances and unhelpful setbacks along the way.  It is difficult to translate complex medical findings into the sort of easily understood language that newspapers rightly demand of their writers.  A daily publication full of precisely accurate but incomprehensible medical stories would soon fold through lack of readership.

By all accounts, the findings of the Georgetown team are a step in the right direction.  Whether that step is a stride, a stroll or a creep is another question, which (judging by my own little study) will be answered according to the amount of one’s prior understanding and knowledge of the subject.

So my message to you, for what it’s worth, is please read on – with care and caution.   And then discuss further.