Changes in the brain are detectable years before devastating memory loss.

In April 2011, the National Institute on Aging and the Alzheimer's Association released revised guidelines for the diagnosis of Alzheimer's disease (AD), including criteria for spotting the disease before it develops into full-blown dementia. The guidelines also address the experimental use of biomarkers that may help diagnose AD earlier. (A biomarker is a measurable substance or condition in the body that can indicate the presence or absence of a disease.) The revised guidelines and criteria appeared online April 19, 2011, in the journal Alzheimer's & Dementia (www.alzheimersanddementia.org/content/ncg).

Numerous studies have identified a correlation between higher consumption of the omega-3 fats contained in fish and fish oil and a lower risk of dementia and cognitive decline. Dig a little deeper, and one of the two main omega-3s, docosahexaenoic acid (DHA), seems to deserve most of the credit. Donepezil (Aricept) and other cholinesterase inhibitors are the most common treatment for mild to moderate Alzheimer's disease. But, at best, they somewhat slow down the pace at which Alzheimer's gets worse, and the side effects are a problem. With the lack of effective treatment and DHA's promise — and low cost — a study to see if the omega-3 might benefit people in the early stages of Alzheimer's disease would seem worth a try.

The Alzheimer's Disease Cooperative Study (ADCS), a consortium of Alzheimer's disease clinics with funding from the federal government to run clinical trials, conducted a high-quality (randomized, double-blinded, placebo-controlled) trial of DHA. About 400 patients with mild-to-moderate Alzheimer's were assigned to take either 2 grams of DHA derived from algae or a placebo pill every day for 18 months. (Algae-derived DHA is becoming popular because of concerns about overfishing and contamination with pollutants and the growing number of people adhering to vegan diets.) The study participants took a battery of tests to measure attention, language, and other cognitive abilities at the beginning and end of the study.

Alzheimer's and driving ability

As people grow older, their vision, hearing, reflexes, strength, flexibility, and coordination tend to deteriorate. These physical changes can undermine driving skills, such as being able to see and hear other vehicles, stop suddenly, navigate an intersection safely, or maintain control of a car. Alzheimer's disease only compounds age-related challenges by impairing memory, insight, and reasoning.

As Alzheimer's progresses, for instance, a patient may have trouble remembering how to get somewhere, or may become confused (such as stopping at a green light or stepping on the gas pedal instead of the brake).

Research we’re watching

The Framingham Heart Study—which has charted the lifestyles and health status of the residents of Framingham, Mass., since 1948—has been tracking the development of dementia among participants since 1975. In a recent analysis, published in the Feb. 11, 2016, issue of The New England Journal of Medicine, researchers calculated the dementia rate among 5,205 people ages 60 or older. The participants had physical exams, including tests for dementia, every five years. The researchers determined that the five-year rate of dementia was 3.6% between 1982 and 1986, 2.8% between 1991 and 1996, 2.2% between 1998 and 2003, and 2.0% between 2009 and 2013. Moreover, the average age when dementia was diagnosed went from 80 to 85 over those three decades.

The declining dementia rate was registered only in high school graduates, but they made up most of the Framingham participants. The rate of cardiovascular disease—including stroke, atrial fibrillation, and heart failure—also fell during the three decades. In that sense, the results give further support to findings that education (which may build up cognitive reserves) protects against dementia, and cardiovascular disease (which restricts blood flow to the brain) may promote it. They provide encouragement that pursuing a healthy, engaged lifestyle may pay off.