Journal Article Annotations
2016, 4th Quarter
Annotations by Nicholas Kontos, MD and Sean Glass, MD
The finding: Neither retrospective inquiry nor feedback about correctness (regarding a multiple choice learning/recent-recall task) affected “feeling of knowing” in subjects with mild to moderate Alzheimer’s disease. This is particularly interesting in the subgroup of subjects grouped as “moderate” or “shallow” for awareness of their anterograde memory deficits (i.e., those with anosognosia). In a model of anosognosia that includes mnemonic (impaired error integration), executive (impaired error detection), and primary (impaired explicit awareness of errors), these findings point to the latter type as the best explanation of anosognosia for cognitive impairment in Alzheimer’s disease.
Strength and weaknesses: Introduction contains a nice review of the concept of anosognosia in Alzheimer’s disease, along with a breakdown of its possible dimensions. The writing is not the clearest, and there are no figures to illustrate the concepts. The study itself is performed in a thoughtful manner, although the diagnosis of probable Alzheimer’s, based merely on MMSE score, seems a bit sketchy. This makes for a potentially heterogeneous sample.
Relevance: The concept of anosognosia is too often confined to right parietal strokes in medical education. In neuropsychiatric practice, however, it is found in disorders ranging from Wernicke’s aphasia, to schizophrenia, to the dementias, as seen in this study. A better understanding of the roots of anosognosia for cognitive impairment in Alzheimer’s disease can help clinicians explain this frustrating phenomenon to caretakers, even if the findings here do not lend themselves readily to therapeutic intervention.
The finding: A computerized cognitive assessment (including the Stroop Test, the Symbol Digit Modalities Test, and the Paced Auditory Serial Addition Test 2-second Trials) detected cognitive impairment in more than 50% of participants with TBI who were deemed cognitively intact on the MoCA test (those with a cutoff of 26/30 or greater occurring at least 3 months after brain injury). These tests were performed to detect problems with executive functioning, information processing speed, and working memory. The MoCA and the three aforementioned batteries took approximately 10 minutes each. Deficits seen on the computerized tests were independent from psychiatric comorbidities and were associated with greater psychosocial dysfunction, as measured on the Rivermead Head Injury Follow-up Questionnaire. This measure has items related to the quality of work, relationships, and domestic activities.
Strengths: The study was performed on consecutive patients in a general hospital setting and the number of participants with mild versus moderate versus severe TBI mirrors the known prevalence data in the general TBI population. The battery does not take long to complete, is easy to learn and administer, and the tests chosen reflect significant cognitive functions that negatively impact functioning in various domains as well as quality of life.
Weaknesses: While the three tests in the sample are useful at detecting critical cognitive functions that may be missed by the MoCA exam, they are much more specific and could very well miss other critical deficits in patients who were excluded from the study (particularly those with CNS disease or more severe psychiatric comorbidities—who are at an increased risk of TBI). Furthermore, the study was not geared to detect possible relevant confounders such as comoribid psychiatric symptoms and emotional distress. Finally, the study did not differentiate between patients with mild, moderate, or severe TBI, which could very well impact the utility of chosen tests.
Relevance: The use of cognitive tests and batteries can greatly aid the diagnosis, treatment, referral, and monitoring of patients with TBI. Many clinicians may become familiar with selected tests (such as questions related to orientation, clock drawing, and verbal recall) or batteries (such as the Mini Mental Status Examination or Montreal Cognitive Exam) which lack sensitivity or specificity for certain disorders, but are nonetheless used because they are “common.”