ROSEMONT, IL. – Experimental technologies for evaluating patients with suspected mild cognitive impairment hold great promise, but until their clinical relevance is well understood, they should not be used in routine practice, Dr. Paul B. Rosenberg said at a conference sponsored by the American Association for Geriatric Psychiatry.
Clinically, magnetic resonance imaging (MRI)is already useful for ruling out unusual causes of cognitive impairment such as a brain mass, occult subdural hematoma, and stroke, said Dr. Rosenberg, a neuropsychiatrist with Johns Hopkins University, Baltimore.
In the research arena, however, MRI is being taken to the next level. By visualizing hippocampal volume loss in patients, for example, the imaging technology is helping to define subtypes of mild cognitive impairment (MCI).
Likewise, genotyping is being used to identify carriers of the apolipoprotein ϵ4 (apo ϵ4) allele, which has been shown to be associated with an elevated risk of converting to Alzheimer's disease. But for many reasons, these experimental applications of available technologies should remain in the research setting for now, Dr. Rosenberg cautioned.
Genotyping for apo ϵ4 is particularly controversial. “Personally, I'd like to do it for my own curiosity, but ethically I don't. … I'm worried about patients getting blackballed. The mere fact that a patient got tested [for apo ϵ4] may bar them from getting long-term care insurance,” he said.
Clinicians may be tempted to perform genotyping because of a study in which the treatment effect of donepezil (Aricept) was more significant and lasting in patients who were apo ϵ4 positive (N. Engl. J. Med. 2005;352:2379–88). But the same investigation also showed that donepezil was no more effective than vitamin E or placebo in slowing progression to Alzheimer's at 36 months.
The results underscore the need for more effective interventions before routine genotyping would be practical, Dr. Rosenberg said.
Unlike Alzheimer's patients, who are often unaware of their cognitive decline, people with MCI will complain of memory problems when they present. “These are the most anxious patients I've ever worked with. … They are absolutely terrified they have [gotten] that disease [Alzheimer's], and it's no less scary than thinking you've got cancer,” he said.
The diagnostic work-up for MCI should include interviews, family and medical histories, functional assessments, and psychiatric, cognitive, and neurologic exams.
During interviews, be alert to complaints about forgetting names, problems doing bills, repeating stories, and forgetting appointments. Getting lost in unfamiliar environments is frequently the first sign of MCI, he said.
MCI patients rarely present with complaints that they no longer remember how to do things such as drive a car, which is a well-ingrained skill that doesn't require much short-term recall.
Patients and family members should be interviewed separately to avoid prompting and to tease out difficult issues such as violence.
If a cognitive deficit isn't indicated in the patient history, it's unlikely it will be found on further examination, he noted.
Functional assessments should address topics such as activities of daily living, social life, and functioning on a job. But with retirement, cognitive impairment may be less apparent as patients face fewer cognitive challenges in their daily lives.
A past history or current symptoms of depression, anxiety, or irritability on a psychiatric exam are particularly noteworthy because they are risk factors for conversion to dementia.
Results from a prospective study indicated that a staggering 85% of MCI patients who were depressed went on to develop dementia at 3 years, compared with only 32% of nondepressed MCI patients (Arch. Neurol. 2004;61:1290–3).