Subjective Versus Objective Assessment of Cognitive Functioning in Primary Care

Courtney Hess, MS; Boaz Levy, PhD; Ardeshir Z. Hashmi, MD; Jacqueline Hogan, MS; Sarah Greenspan, MS; Allison Elber, MA; Kathryn Falcon, MS; Daniel F. Driscoll, MD

Disclosures

J Am Board Fam Med. 2020;33(3):417-425. 

In This Article

Abstract and Introduction

Abstract

Purpose: This study examined the clinical utility of highly efficient subjective and objective screens of cognitive impairment.

Method: Participants (N = 124, age ≥ 65, mean = 73.59, SD = 6.26) completed a 2-item questionnaire of subjective memory functioning, a brief computerized cognitive test, and the Montreal Cognitive Assessment (MoCA). Next, participants were assigned to 1 of 4 conditions, based on their subjective (low/high) and objective (impaired/unimpaired) levels of cognitive functioning. Further analysis divided the sample into age-based groups (ie, age < 75, age ≥ 75).

Results: The proportion of participants in the impaired subsample (ie, MoCA < 26), who reported a high level of subjective concern about their memory, was low (ie, 0.15). Among unimpaired participants, analysis detected significant group differences across subjective memory levels (P < .0003) and age (P < .005) categories on one of the three tasks of the computerized test (ie, cognitive control). In contrast, the MoCA offered no differentiation between these groups.

Conclusion: Screening protocols in which cognitive testing is administered subsequent to patient complaint are prone to underdiagnosis. In addition, common dementia screens are insensitive to subjective deficits and healthy cognitive aging. Therefore, they may lead to dismissing valid concerns that deserve preventive attention. Primary care needs efficient screening tools that are sensitive to prodromal decline.

Introduction

Engaging primary care in the early detection of neurocognitive disorders is likely to promote healthy aging in the community.[1,2] Results of a high-quality clinical trial indicate that early behavioral and lifestyle interventions reduce the cognitive decline expected in at-risk aging adults.[3] Additional evidence, summarized in systematic and metanalytic reviews of population-based studies, have led the Alzheimer's Association to conclude that regular physical activity, cognitive training, diet, and effective management of medical risk factors reduce the risk of cognitive impairment and dementia.[4–6] Beyond notable prophylactic and clinical gains, early detection can reduce the cost of care, decrease family stress, and improve overall illness management.[7–10]

These advances collectively challenge widely held notions about the limited treatability and preventability of dementia,[11] or the value of making a diagnosis per se.[12] In this regard, the new evidence attenuates previous arguments against community-wide screenings.[12,13] Accordingly, the debate about public screenings for dementia has now shifted in favor of implementation, as reflected by new policies, such as the Affordable Care Act, which explicitly require health assessment protocols for Medicare clients to include a cognitive evaluation during the annual wellness visit.[14] This development will likely place the task of screening the public within the purview of primary care; however, the clinical protocols and guidelines for effective application in this setting have not yet been fully developed.[15]

At present, many primary care physicians assess cognitive functioning subsequent to patient complaints. However, this stepwise model, in which the objective assessment of cognitive functioning follows a voluntary complaint, may be insensitive to early detection of impairment. Screening all patients for subjective complaints with self-report questionnaires may improve detection rates; yet, concerns surrounding underdiagnoses are likely to persist, as some patients may be unaware of their deficits due to anosognosia,[16,17] whereas others may eschew the issue altogether because of the shame and dread associated with prospective dementia.[7]

An alternative approach to screening may reverse the stepwise model. It would extend the objective assessment to all patients and proceed with a clinical interview subsequent to positive findings. This general strategy, however, may be fraught with psychological disadvantages. The research on motivational interviewing in primary care settings points to a clear connection between physician insight into the patient's subjective assessment of the problem (eg, awareness, significance, readiness to change) and clinical outcome, especially when interventions rely primarily on lifestyle changes.[18,19] In this regard, the first conversation about the results of a medical evaluation seems to be particularly influential and should therefore be informed by the subjective assessment of patients.

Following this line of reasoning, a model of preventive screening that incorporates both subjective and objective measures, as a standard of care, may address the aforementioned concerns; yet, it still needs to contend with clinical decisions around disagreement between objective test results and subjective patient report. Specifically, it is unclear when a negative (ie, unimpaired) outcome of an objective screening procedure would be sufficient to assuage patient concerns about cognitive dysfunction, and thereby avoid a costly referral to neuro-cognitive diagnostics. This issue raises questions related to screen sensitivity, particularly in prodromal patients who report a worrisome decline in cognitive functioning, while maintaining adequate functional adjustment for their circumstances.

To address these questions, the current study aimed to assess the agreement between subjective and objective measures in a community sample. The main hypothesis was that sensitivity to subjective complaints would be associated with test challenge. More specifically, common dementia screens (eg, MiniCog, Mini Mental Status Examination [MMSE], Montreal Cognitive Assessment [MoCA]) suffer from a ceiling effect, because they are not designed to assess cognitive limits. Instead, they indicate impairment by failing a lower, predetermined set of challenges. For this reason, they may mask prodromal declines and, as a result, contradict valid complaints. In theory, the low ceiling of ordinary dementia screens decreases their sensitivity to the prodromal decline that occurs while patients still function within the range of normal limits.

A higher ceiling provides the performance range needed to differentiate prodromal decline from normal aging. Thus, in otherwise comparative samples, on a test with a higher ceiling and more challenging tasks, prodromal patients would probably score lower, on average, than cognitively healthy people. Stated differently, the intersection between lower test performance and subjective concerns may elevate the probability for prodromal decline.[17] This hypothesis carries implications to practice. Alongside the outcome of standard dementia screening, indication from a more challenging test would probably help to interpret patients' complaints more accurately and, consequently, lead to better decisions about subsequent care. Of note, although prodromal status is difficult to establish with a high degree of certainty, either in research or in practice, the combination of subjective deficits and a lower-than-expected performance on objective measures may point to increased risk that deserves attention.

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