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Work that involves complex thinking and interaction with other people seems to help protect against the onset of Alzheimer’s disease, according to research presented Sunday at the Alzheimer’s Association’s International Conference in Toronto.

Two studies looked at how complex work and social engagement counteract the effects of unhealthy diet and cerebrovascular disease on cognition. One found that while a “Western” diet (characterized by red and processed meats, white bread, potatoes, pre-packaged foods and sweets) is associated with cognitive decline, people who ate such food could offset the negative effects and experienced less cognitive decline if they also had a mentally stimulating lifestyle.

Occupations that afforded the highest levels of protections included lawyer, teacher, social worker, engineer and doctor; the fewest protections were seen among people who held jobs such as laborer, cashier, grocery shelf stocker and machine operator.

“You can never totally forget about the importance of a good diet, but in terms of your risk of dementia, you are better able to accommodate some of the brain damage that is associated with consuming this kind of (unhealthy) diet,” said Matthew Parrott, a post-doctoral fellow at the Rotman Research Institute in Toronto, who presented the study.

In another study, researchers found that people with increased white matter hyperintensities (WMHs) — white spots that appear on brain scans and are commonly associated with Alzheimer’s and cognitive decline – were able to better tolerate WMH-related damage if they worked primarily with other people rather than with things or data.

Occupations involving “mentoring” — such as social worker, physician, school counselor, psychologist and pastor — were considered most complex, said Elizabeth Boots, a research specialist at the University of Wisconsin and the study’s presenting author. Work involving taking instructions or helping was considered least complex. The study, conducted by the Wisconsin Alzheimer’s Disease Research Center and Wisconsin Alzheimer’s Institute, focused on people who were cognitively healthy but at risk for Alzheimer’s.

“By showing that cognitive reserve is already at work early in the disease process, we believe this could have potential implications for early intervention, such as identifying those with potentially lower reserve and suggesting ways to boost that reserve in some way,” Boots said, adding that it could be possible for those with lower reserve to implement more complex skills into their daily lives.

The studies support previous findings that more stimulating lifestyles are associated with better cognitive outcomes later in life and bolster the importance of intellectual engagement, said Ronald Petersen, director of the Mayo Clinic Alzheimer’s Disease Research Center and the Mayo Clinic Study of Aging.

“Physical activity has been reasonably well-documented, but with intellectual activity the data get pretty soft. . . . These two studies speak to that,” he said. “What it may mean is the development of Alzheimer’s disease or cognitive change with aging need not be a passive process; you can do something about it. . . . Staying intellectually active whether it be your job or other kinds of activities may actually be beneficial.”

When it comes to training your brain, speed may be more important than content. Researchers at the conference presented 10-year results from the advanced cognitive training for independent and vital elderly, or ACTIVE, study, which looked at the impact of different kinds of brain training on 2,785 older adults across the United States.

They were divided into three groups who received classroom-based memory strategies, classroom-based reasoning strategies and computerized speed-of-processing training, along with a control group. The groups had 10 60-minute training sessions over five weeks, and some received booster sessions a year and three years after the training.

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After 10 years, only the speed-of-processing group showed an effect: a 33 percent reduction in new cases of cognitive impairment or dementia, which rose to 48 percent among those who had participated in the booster session. The other two training groups did not show a significant difference from the control group.

A newly identified condition — mild behavior impairment (MBI) — may precede the onset of Alzheimer’s before symptoms of memory loss become apparent, according to new research also presented Sunday at the conference.

Typically, memory loss has been the primary hallmark of Alzheimer’s. However, other signs such as anxiety, confusion and disorientation often become apparent first. MBI defines a set of neuropsychiatric symptoms, acquired in later life and sustained over six months, which doctors can use as a checklist to detect the disease earlier.

The list is made up of five categories of symptoms: apathy, mood, impulse control, social appropriateness and perception.

“Research is increasingly showing that if you’re a midlife or older adult and you have a new onset of any of those neuropsychiatric symptoms, then you’re more likely to decline and go on to mild cognitive impairment or dementia,” said Zahinoor Ismail, a specialist in neuropsychiatry at the Hotchkiss Brain Institute at the University of Calgary who presented the new condition at the conference.

Symptoms include sadness, disorientation, panic episodes, aggressiveness or argumentativeness, frustration, stubbornness, hoarding and substance abuse.

Until now, such symptoms have not always been seen as precursors to dementia, resulting in inappropriate treatment, Ismail said. “Often these people end up under psychiatric care and . . . end up being prescribed pharmaceuticals. . . . If these symptoms are identified earlier, that can change the course of treatment, from antipsychotic to dementia treatment.”

Maria Carrillo, the Alzheimer Association’s chief science officer, praised the proposed checklist, saying it “has the potential to represent a paradigm shift.”