VIENNA— Anosognosia can occur in the earliest stages of Alzheimer’s disease and can affect more than 40% of patients, complicating their management. According to Mateja de Leonni-Stanonik, MD, PhD, anosognosia is “usually manifested in patients with Alzheimer’s disease as an unawareness of cognitive deficits.” The mechanism of anosognosia remains unknown, “but several studies show that patients with Alzheimer’s disease and anosognosia have significantly more severe deficits on frontal lobe–related neuropsychological tests,” she said in her remarks to the 6th Congress of the European Federation of Neurological Societies. Dr. de Leonni-Stanonik is a fellow in neuroradiology and nuclear medicine in the Department of Radiology at the Cole Neuroscience Center of the University of Tennessee Graduate School of Medicine, Knoxville.

ANOSOGNOSIA QUESTIONNAIRE

In order to identify the area of the brain affected in patients with mild Alzheimer’s disease and anosognosia, Dr. de Leonni-Stanonik and colleagues John H. Dougherty, Jr, MD, and Charles A. Licata, MA, developed the Cole Anosognosia Scale for Alzheimer’s Disease (CAS-AD) “to allow patients to rate their feelings and opinions towards specific aspects of their behaviors and cognitive abilities. The CAS-AD covers symptoms in three categories: memory, executive functioning, and behavior. The questionnaire is designed to be understood by cognitively impaired patients. There is also a similar informant questionnaire for the caregiver to rate the patient,” she explained.

There are 39 items on the CAS-AD, and each item is rated on an analog scale from “never” to “always.” This item is then converted to a score between 1 and 5. Samples from the memory section include: “I forget the date; It is hard for me to locate items around the house; I can remember where I live.” The corresponding items on the informant questionnaire are: “The client forgets the date; It is hard for the client to locate items around the house; The client can remember where he or she lives.” Significant discrepancies between patient and caregiver scores suggest the presence of anosognosia.

The researchers administered the CAS-AD to 10 patients with mild Alzheimer’s disease (Mini-Mental State Examination [MMSE] score, 20 to 25). Six of the 10 patients had abnormal CAS-AD scores. There were three males and three females with anosognosia, with a mean age of 75.5. The four patients without anosognosia were male, with a mean age of 73.6. Mean MMSE scores were 23.3 for the patients with anosognosia and 23.8 for those without.

BRAIN IMAGING

All 10 patients had baseline magnetic resonance imaging (MRI) and fluorodeoxyglucose positron emission tomography (FDG-PET) scans. According to Dr. de Leonni-Stanonik, “this is the first study which employs FDG-PET in conjunction with objective anosognosia assessment to identify the potential neural substrate of anosognosia in mild Alzheimer’s disease.”

There were no significant anatomic abnormalities on the MRI scans. Twenty minutes prior to PET scan, the patients were subjected to a cognitive stressor, the Stroop test. After the FDG-PET results were coregistered with the patients’ MRI scans, five of the six patients with anosognosia demonstrated decreased inferior anterior cingulate cortex and right posterior parietal glucose uptake. In addition, the magnitude of decreased glucose uptake in the anterior cingulate cortex correlated with the severity of the anosognosia score.

Given the role of the anterior cingulate cortex in attention, Dr. de Leonni-Stanonik postulated, “anosognosia may represent a deficit in the ability of focusing selective attention on one’s self.” She noted that quantitative analysis was necessary to elucidate these findings because “on qualitative images, one could not tell the difference between the baseline and activation FDG-PET scans.”

IN DENIAL?

Dr. de Leonni-Stanonik commented that denial could be confused with anosognosia. However, “we have a battery of other tests to assess denial, and the question of denial is also addressed by interviews with the family,” she observed. “For these patients, it’s not denial; it truly seems to be their unawareness and subsequent inability to recognize that something might be wrong with them—that is, anosognosia. Therefore, anosognosia may represent a specific defect in selective attention in Alzheimer’s disease,” she concluded.

—Andrew Wilner, MD

Suggested Reading
de Leonni-Stanonik M, Dougherty JH, Licata CA, et al. Anosognosia in mild Alzheimer’s disease: revelations by FDG-PET. Eur J Neurol. 2002;9(suppl 2):42.
Gil R, Arroyo-Anllo EM, Ingrand P, et al. Self-consciousness and Alzheimer’s disease. Acta Neurol Scand. 2001;104:296-300.

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