April 19, 2011 -- Alzheimer's disease should be diagnosed early, before a person develops severe, late-stage dementia, new guidelines suggest.
It's been 27 years since guidelines for diagnosing Alzheimer's disease were laid out. Since 1984, research has shown Alzheimer's to be a disease that begins decades before dementia appears.
Now panels from the National Institute on Aging and the Alzheimer's Association have split Alzheimer's disease into three stages:
Dementia, including mental impairments not as severe as those previously required for an Alzheimer's diagnosis.
Mild cognitive impairment due to Alzheimer's disease. This new category of Alzheimer's disease includes patients with changes in memory and thinking ability that do not keep them from performing everyday functions, but which strongly suggest that a patient will develop Alzheimer's dementia.
Preclinical Alzheimer's disease. The new guidelines recognize that the Alzheimer's disease process begins before there are any symptoms. But for now, there aren't good enough tests to tell whether a person has this stage of Alzheimer's.
Perhaps the biggest change is the way doctors will diagnose Alzheimer's dementia, says Gary Kennedy, MD. Kennedy, a geriatric psychiatrist who specializes in treating patients with Alzheimer's disease at Montefiore Medical Center in New York, was not a member of the guideline-writing committees.
"The real new component here is you need not have memory impairment to have Alzheimer's dementia. They are ratcheting down the dementia criteria," Kennedy tells WebMD. "If you're having trouble making plans, have problems adapting to changes in your environment, or have lapses that impair your social involvement with others, you may have Alzheimer's disease even if your memory is not so bad."
Also new is that the guidelines assume it is possible to identify people with mild cognitive impairment whose worsening symptoms likely reflect an early stage of Alzheimer's disease.
The criteria for diagnosing mild cognitive impairment due to Alzheimer's disease are:
Concern expressed by a patient, family member, friend, or doctor, about a change in mental function: specifically, memory, reasoning/problem solving, language ability, visual/spatial skills, or ability to pay attention.
Objective evidence, usually test results, showing that a patient has one or more of these changes in mental function.
The person is still independent and able to carry out everyday functions.
The person is not demented.
"'Mild' here means you are not socially impaired, but it does imply you know there is a problem, and your family and friends notice a problem," Kennedy says.
The problem, of course, is that many people with mild cognitive impairment deny there is a problem.
"So the criteria need refinement," Kennedy says. "This is more of a provisional diagnosis. That is why the guidelines put an emphasis on biomarkers -- signposts that dementia may be down the road."