A new method of detecting the early signs of dementia has proved 100% accurate in a preliminary study at the University of Cambridge. The research was conducted on patients attending the Addenbrooke's Hospital Memory Clinic.

Dr Andrew Blackwell, Professor Barbara Sahakian and their colleagues found that two simple tests of learning and memory combined with the person's age was sufficient to calculate with 100% accuracy the probability that someone with mild memory impairment will go on to develop a diagnosis of probable Alzheimer's disease 32 months later.

Blackwell and Sahakian and colleagues are now applying this algorithm to a non-clinic sample of the elderly population and it is proving very sensitive to cognitive deterioration.

Blackwell commented:

"We believe this to be an important breakthrough in our understanding of the early stages of Alzheimer's disease."

The new system is not only more accurate than other tests currently used; in aiding early detection it promises more prompt and effective treatment. Sahakian is optimistic about the potential benefits:

"Many pharmaceutical companies are committed to finding effective treatments for Alzheimer's disease - whether with anti-amyloid deposit agents, cholinergic drugs or disease modifying agents. Early detection will maximise the therapeutic benefit of treatment and enhance quality of life for patients and their families. In so doing it will also reduce the burden on residential and nursing care services."

But the researchers urge caution about the important issues raised by their findings.

"Our research raises compelling ethical questions. For example, what are the implications of identifying individuals in the prodromal stage of AD? What is the impact on the individual in regard to support and care? What are the implications for early treatment? In addition, it is important to remember that patients who are in the later stages of Alzheimer's disease also need effective treatments for the cognitive and behavioural consequences of this devastating disease."

According to the Alzheimer's Society dementia currently affects over 700,000 people in the UK. Approximately 18,500 people with dementia are under the age of 65. Dementia affects one person in 20 over the age of 65 and one person in five over the age of 80. The number of people with dementia is steadily increasing. Alzheimer's disease is the most common form of dementia, making up 55 per cent of all cases of dementia.

'Detecting Dementia: Novel Neuropsychological Markers of Preclinical Alzheimer's Disease' by Blackwell AD, Sahakian BJ, Vesey R, Semple JM, Robbins TW, Hodges JR. appears in Dementia and Geriatric Cognitive Disorders Vol 17 Nos 1-2, 2004 and is published online this week.

The study was funded by a Medical Research Council LINK grant with GlaxoSmithKline and by the Wellcome trust.

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