A clinical trial based in Medellin, Colombia, could help us understand how to identify and possibly treat Alzheimer’s disease.

Margaret Lock, professor of social studies in medicine at McGill, cited this study as part of her overview of the research in The Alzheimer’s Enigma in an Aging World at this year’s prestigious Osler Lecture, delivered last month at McGill.

The subject group in the Colombia study is from 25 extended families of Basque origin in Spain now numbering about 5,000 living in urban and rural areas, mainly around Medellin.

“These families comprise the most concentrated group of biologically close-knit individuals anywhere, all of whom carry a specific mutation of the gene presenilin 1.” It is one of the genes associated with early AD onset.

Early onset means memory loss around the age of 45, with full-blown AD by early 50s.

The research team under neurologist Dr. Francisco Lopera, who first identified this form of dementia due to a gene mutation, found that 1,500 of them are expected to develop early-onset Alzheimer’s, also known as the Paisa variation.

In spite of the evidence of identical brain lesions in early and late onset AD, Lock said she and “many eminent researchers” do not think they are one and the same. “Why so often in older brains is there a striking lack of correspondence between clinical signs of dementia and supposed neuro-pathology?” she asked, also noting, “the dilemmas of Alzheimer’s remain.” While waiting for researchers to develop effective drugs, Lock emphasized combating poverty to ensure better nutrition, sanitation, and education is crucial to improved neurological health.

“Dementia does not suddenly hit in old age, and biological detection of those at risk for aging, if proven effective, will only be available for a very small minority of the world’s population,” she cautioned.

Without a cure or preventive drug, the best way to prevent or postpone AD onset is “reduction of toxic environments, junk-food, smoking, obesity, and diabetes – all factors that reduce the risk of vascular dementia, and hence AD.”

Reducing isolation and loneliness for seniors can also combat AD onset, she said.

Scientists have identified as significant risk factors such neurotoxins as DDT exposure and residues in human blood, exposure to aluminum and the metal lead in-utero, with long term effects.

Two 2014 studies, funded by the U.S. National Institute of Health, have shown that a person’s epigenome – the chemical modifications, or markers, on our DNA that turn gene activity on and off – may influence Alzheimer’s disease-related changes in the brain. These changes may begin to show up before cognitive impairment is perceived.

Then again, Lock stressed, these physiological changes are detected in “normal aging, indicating that other unknown factors must somehow be implicated.”

AD prevalence, in some societies, may improve over time. In the U.K., the Cambridge Group under
Dr. Carol Brayne studied more than 7,000 seniors aged 65 and over, one group from 1984-1994, and a second from 2008-2011. “The results show that dementia rates had dropped by about 24 per cent over the years between sampling.”

A Danish study compared a group born in 1905 and assessed at 93 years old, and another born in 1915 and assessed at 95 years old. “The 1915 cohort scored significantly better on cognitive testing and being able to carry out daily activities independently.”

Similar findings in Sweden, Germany, and the U.S. indicate that “the mantra of a pandemic of Alzheimer’s rising exponentially year by year may have to be modified, though there will be regional variations.”

The annual Marva Whyte Alzheimer’s Awareness Conference, titled Confusion, Delirium and Dementia – The Myth and Reality of Aging, with Drs. Howard Chertkow and Serge Gauthier, is to be held January 20 at Hotel Ruby Foo, 7655 Decarie. Details and registration: 514-485-7233, info@agiteam.org.