Neuropsychological Evaluations in Adults

Family physicians are often the first health care professionals to evaluate patients with memory loss and cognitive dysfunction. Although many patients can be readily diagnosed and treated, some present significant challenges. A neuropsychological consultation can help characterize cognitive deficits, clarify diagnoses, and develop optimal management plans for patients with cognitive issues.¹ Common goals of neuropsychological evaluations are provided in Table 1.²

Clinical neuropsychologists are doctoral-level psychologists who have fellowship training in assessment and intervention principles that are based on the scientific study of human behavior as it relates to normal and abnormal brain functioning.¹ Neuropsychologists use validated puzzle-based materials, oral questions, and written tests to objectively assess multiple cognitive and emotional functions (Table 2). The tests are typically standardized using large normative samples of healthy age-matched individuals, allowing the examiner to determine the degree to which performance deviates from expected ranges. The results of neuropsychological testing are integrated with other sources of information to provide a comprehensive assessment of a person's cognitive, behavioral, and emotional functioning as a basis for clinical decisions (Table 3).²

Neuropsychological tests are different in purpose and scope from cognitive screening tests such as the Mini-Mental State Examination³ (Table 4). Screening tests usually take five to 10 minutes to complete and are designed to screen for general cognitive impairment that may warrant a more comprehensive workup. Although screening tests can indicate problems in general cognitive functioning, they have poor ability to assess for deficits in specific cognitive domains. This has been highlighted by research showing that screening test items weakly correlate with scores in the same cognitive domains on neuropsychological testing (correlations range from 0.04 to 0.46).⁴ Neuropsychological testing typically requires several hours to complete because it comprehensively examines multiple cognitive domains to provide a detailed assessment of the nature and severity of cognitive impairments. This information can contribute significantly when determining primary and secondary diagnoses and planning an individualized rehabilitation/treatment plan.³

Neuropsychological evaluations are often complementary to neuroimaging and electrophysiologic procedures.⁵ Computed tomography and magnetic resonance imaging evaluate structural integrity within the central nervous system to identify atrophy and lesions. Electroencephalography detects electrical activity of the brain, which is commonly used to assess for epileptic activity. Positron emission tomography identifies cerebral glucose metabolism to determine whether brain activity is reduced in specific regions. However, these procedures have limited diagnostic sensitivity for some neurologic conditions and cannot assess the functional output of the brain. Neuropsychological testing provides an objective assessment of the cognitive, behavioral, and emotional manifestations from cerebral injury or disease.

Because of the unique data that neuropsychological testing provides, physicians have increasingly utilized neuropsychological services.⁵ In satisfaction surveys, more than 80% of primary care physicians reported that referral questions were satisfactorily answered, and approximately 90% agreed with the diagnostic impressions and treatment recommendations.⁶ Overall, they found the consulting report useful, and they indicated they would continue to refer patients for neuropsychological evaluations. Commonly referred clinical conditions and primary care referral questions are listed in Table 5.^6,7

Commonly used neuropsychological test batteries are highly reliable, with reliability coefficients often at or above 0.90 for cognitive index scores.⁸ Neuropsychological validity studies indicate that tests perform as anticipated in clinical situations. For example, patients with right temporal lobectomies perform below the normative mean on visual memory tests, whereas those with left temporal lobectomies perform below the normative mean on verbal memory tests.⁸ Patients with right parietal lobe lesions perform poorly on visuospatial constructional tests; those with left-hemisphere lesions perform poorly on expressive verbal ability tests; and those with frontal lobe lesions perform poorly on executive functioning tests.^9,10 Empiric evidence for the use of neuropsychological evaluations in persons with dementia, mild cognitive impairment, traumatic brain injury (TBI), and other clinical conditions is summarized below.

DEMENTIA AND MILD COGNITIVE IMPAIRMENT

Guidelines from several organizations stress the importance of neuropsychological assessment in the diagnosis and management of dementia. The National Institute on Aging–Alzheimer's Association Workgroup recommends that neuropsychological testing be conducted when the clinical history and mental status examination do not yield confident diagnoses.¹¹ The European Federation of Neurologic Societies–European Neurologic Society states that cognitive assessment has a key role in the diagnosis and management of dementia.¹² The International Statistical Classification of Mental and Behavioural Disorders, 10th rev., and the Diagnostic and Statistical Manual of Mental Disorders, 5th ed., state that neuropsychological testing is the preferred method for examining and documenting cognitive dysfunction.^13,14 Figure 1 shows an approach to evaluating and managing patients with suspected dementia²; an alternative algorithm that includes the neuropsychological evaluation is available in a recent American Family Physician article (https://www.aafp.org/afp/2018/0315/p398.html#afp20180315p398-f1).

Neuropsychological testing can differentiate Alzheimer dementia from nondementia with nearly 90% accuracy,¹⁵ with even higher rates when demographic factors are incorporated with test data (area under the curve = 0.98).¹⁶ Neuropsychological evaluations improve diagnostic accuracy even when diagnoses are informed by imaging results and evaluation by subspecialists.^17,18 Additionally, studies have shown that neuropsychological testing can differentiate dementia from psychiatric conditions with accuracy rates near 90%.¹⁹

Although Alzheimer disease is the most common cause of dementia in adults 60 years and older, dementia is often the result of other disease processes (e.g., Lewy body disease, cerebrovascular disease). Understanding the cause of a patient's dementia can guide family physicians in prescription decisions (e.g., whether to start an acetylcholinesterase inhibitor) and expectations about future symptoms and treatment needs.²⁰ Neuropsychological testing can be a useful tool in this regard, with studies demonstrating strong accuracy in discriminating between different types of dementia.^21,22 Neuropsychological testing can also distinguish mild cognitive impairment from normal functioning; sensitivity and specificity rates are approximately 75% and 80%, respectively, when well-established diagnostic criteria are used.^15,23 Serial assessments can be useful for patients with mild cognitive impairment or in cases where the etiology of cognitive decline is unclear. A 12-month follow-up is often used to determine whether patterns of cognitive decline are consistent with a suspected etiology, identifying conversion of mild cognitive impairment to dementia, or to monitor the rate of cognitive change over time.⁵

Neuropsychological assessments are helpful in tracking changes that may affect daily functioning as cognitive impairment and dementia progress.⁵ Approximately 40% to 50% of the variance in functional decline (i.e., ability to perform personal care activities) is accounted for by cognitive decline.²⁴ In at least 50% of cases, neuropsychological testing can indicate when a patient needs assistance with daily activities.²⁴ Among the challenging situations in which neuropsychological evaluation can be helpful are assessing driving safety and determining health care decision-making capacity. Reduced visuospatial abilities moderately predict on-road driving performance.²⁵ The American Bar Association and American Psychological Association concluded that neuropsychological assessment provides objective information to improve the reliability of capacity determinations.²⁶

TRAUMATIC BRAIN INJURY

Neuropsychologists are often involved in post–acute TBI management to help determine and predict patient-specific cognitive, emotional, and adaptive functioning²⁷ (Figure 2^2,28–30 ). The addition of neuropsychological testing to injury severity variables (e.g., posttraumatic amnesia) increases predicted accuracy in functional outcomes.³¹ In moderate to severe TBI, neuropsychological status can predict functional independence, return to work, disability utilization, responsiveness to cognitive rehabilitation, and academic achievement.^20,32–38

In patients with mild TBI (concussion), in whom long-term cognitive deficits are less likely, a neuropsychological evaluation can identify psychological and other noncognitive factors that may masquerade as cognitive dysfunction and, therefore, can guide appropriate treatment recommendations.²⁸ The Concussion in Sport Group described neuropsychological assessments as a cornerstone of concussion management, and a recent international consensus statement indicated that neuropsychological testing contributes significant information in the evaluation of mild TBI.³⁹ Guidelines recommend that patients who report cognitive symptoms beyond 30 to 90 days after mild TBI be referred for neuropsychological assessment.^28,29

Neuropsychologists routinely use performance validity tests in cases where legal issues may be confounding recovery after TBI. These tests assess the validity of a patient's reported symptoms.⁴⁰ These tests appear more challenging than they actually are; even patients with severe cognitive impairment can perform with near-perfect accuracy. When using cutoff scores and clinical decision rules for multiple tests, accuracy rates are greater than 90%, indicating that results beyond cutoff scores are likely invalid.⁴¹ Given their expertise with typical and atypical sequelae of TBI and empiric methods for detecting invalid presentations, neuropsychologists are often involved in evaluating exaggeration or malingering of cognitive and emotional symptoms in TBI cases.

OTHER CLINICAL CONDITIONS THAT CAN AFFECT COGNITIVE FUNCTIONING

The American Academy of Neurology has endorsed the use of neuropsychological evaluation in the assessment and treatment of a variety of conditions, including cerebrovascular disease/stroke, Parkinson disease, human immunodeficiency virus encephalopathy, multiple sclerosis, epilepsy, neurotoxic exposure, and chronic pain.⁴² Research also demonstrates that neuropsychological evaluations can detect cognitive changes caused by psychiatric conditions such as schizophrenia and bipolar disorder^20,43; identify cognitive changes that may emerge before motor abnormalities in the early stage of Huntington disease⁴⁴; and measure cognitive changes after surgery in patients with brain tumors.⁴⁵ Neuropsychological evaluations can also detect cognitive issues in patients with developmental disabilities, illnesses, and central nervous system abnormalities.²⁷

Referrals for neuropsychological consultation are commonly made by family physicians, neurologists, psychiatrists, and other primary care clinicians. Assessments are typically covered by health insurance if psychological, neurologic, or medical issues are suspected that could affect cognitive or neurobehavioral functioning and if referrals are related to making clinical diagnoses or developing treatment plans. Table 6 shows common indications and exclusions for insurance coverage of neuropsychological evaluations.⁴⁶

Although availability can sometimes be limited, particularly in rural settings, a listing of neuropsychologists certified by the American Academy of Clinical Neuropsychology is available at https://theaacn.org/directory. To reduce patient stress and optimize outcomes, physicians should briefly discuss with patients the reason for the referral, the anticipated benefit of the assessment, and the general testing format. Some patients might initially be apprehensive, but surveys show that more than 90% of patients rated their experience as positive or neutral.⁴⁷ Roughly 80% of patients and their significant others reported that they found the evaluation helpful in understanding and coping with cognitive problems; more than 90% reported being satisfied with the evaluation; and approximately 90% indicated that they would refer others.⁴⁸ A brief pamphlet for patients who are being referred for testing is available at http://www.div40.org/pdf/NeuropscyhBroch2.pdf.

This article updates a previous article on this topic by Michels, et al.²

Data Sources: PubMed, PsychInfo, National Guideline Clearinghouse, and U.S. Preventive Services Task Force were the primary sources for the article. Key words included neuropsychological, neuropsychology, cognitive, cognition, dementia, mild cognitive impairment, brain injury, and concussion. Search dates: July 26, 2017, to October 12, 2018.

Editor's Note: Dr. Walling is an Associate Medical Editor for AFP.