A Medical Device Daily

Those involved in Alzheimer’s disease (AD) research believe that accurate early diagnosis would enable the new generation of drugs to be successfully administered in the first stages of the disease.

Scientists from DiaGenic (Oslo, Norway) presented the prototype of and results of initial trials of a simple blood test for AD at the Alzheimer’s Association (Chicago)-sponsored International Conference on Prevention of Dementia at the Marriott Wardman Park Hotel in Washington earlier this week.

Using peripheral blood as a sample, the test detects a unique gene expression profile or “signature,” DiaGenic said. The company said it expects the test to be available to researchers early next year, paving the way for widespread use.

“The development of a blood-based diagnostic test has been one of the major goals of Alzheimer’s disease research,” said professors Khalid Iqbal and Bengt Winblad. “The new blood ‘signature’ test from DiaGenic is an important step in the right direction.”

They added that the test also is very timely, with several pharmaceutical companies in the process of developing a next generation of therapeutic drugs that can inhibit the underlying pathology of AD. “The test will require validation in a large number of Alzheimer’s and control patients, and at multiple centers, to become useful,” Iqbal and Winblad said.

Researchers combed through many Alzheimer’s patient samples and several thousand genes to identify a common gene signature for Alzheimer’s. The company said the most informative genes isolated in these discovery phase studies were then used to design and develop customized test arrays.

DiaGenic said the prototypes that employ alternate technologies for gene expression profiling have been “extensively tested.” It said a new, mixed cohort of 100 Alzheimer’s disease and age-matched non-Alzheimer’s subject samples was employed in the studies.

CEO Erik Christensen said the results presented in Washington “show that the test can detect Alzheimer’s disease with a clinically acceptable accuracy of above 80%.”

Also at the dementia prevention conference, studies dealt with the relationship between heart health and brain health. One study suggested that treating risk factors for heart disease and stroke, such as high blood pressure and diabetes, may slow the progression of AD.

“The best-known and most solid risk factors for Alzheimer’s are age, family history and genetics, but those are things you can’t change,” said William Thies, PhD, vice president of medical and scientific relations for the Alzheimer’s Association. “Research that identifies lifestyle risk factors gives people actions they can do, and positive choices they can make, to reduce their risk of Alzheimer’s — like lowering their blood pressure and treating their diabetes, or better still avoiding them in the first place. That’s a good research investment.”

Yan Deschaintre, MD, of the Centre Memoire at Hopital Roger Salengro (Lille, France) and colleagues investigated whether vascular risk factors treatment slows cognitive decline once Alzheimer’s and/or vascular dementia is already evident.

The researchers analyzed medical records of patients attending the memory clinic for the first time between 1997 and 2003 who had a final diagnosis of Alzhiemer’s, Alzhiemer’s with cerebro-vascular disease, or vascular dementia. Vascular risk factors sought were high blood pressure, diabetes, dyslipidemia and atherosclerotic vascular disease. The patients were considered treated if they received an antihypertensive, an oral antihyperglycemic or insulin, a statin or a fibrate, an antiplatelet or an anticoagulant.

Among the 891 dementia patients studied, the researchers found that those who had their vascular risk factors treated declined less than those who had not. For people with Alzheimer’s without signs of vascular dementia, vascular risk factors treatment reduced yearly cognitive decline by almost one-third, according to the mini-mental state evaluation (MMSE) score.

“That means the patients whose vascular risk factors were treated declined at a slower rate such that it took them three years to decline as much as untreated patients did after two years,” Deschaintre said. “By slowing dementia progression, vascular risk factors treatment may delay the severe stages and have a significant impact on reducing the burden of dementia.”

Rosebud Roberts and colleagues at the Mayo Clinic (Rochester, Minnesota) investigated whether people who have had a carotid endarterectomy or stroke are more likely to have an impairment in their memory and thinking skills known as mild cognitive impairment (MCI), which is in some cases a precursor to Alzheimer’s.

Some 885 persons aged 70 to 89 in Olmsted County, Minnesota, received a comprehensive examination of memory and thinking skills, and were asked if they had ever had a carotid endarterectomy or a stroke or transient ischemic attack (TIA). 295 persons in the study group were found to have MCI and were age and sex-matched to 590 controls.

Among those who had MCI, 13 of 295 (4.41%) reported having had a carotid endarterectomy, but only 12 of 590 (2.03%) of controls had this surgery. Similarly, 77 (26.1%) MCI cases reported having had a stroke or TIA compared to 83 (14.07%) controls.

“In this population, elderly subjects who have had a carotid endarterectomy or stroke or TIA are about two times more likely to have MCI,” Roberts said. “This may be due to the effects of the severe blockage of blood flow to the brain that made the surgery necessary, or to the effects of the stroke or TIA. Although carotid artery surgery could be associated with complications, an alternate explanation for our findings is that carotid artery surgery may be a marker for generalized atherosclerosis.”