Mrs. M, age 27, suffered a head injury in a motor vehicle accident 9 months ago. She is referred to you by a neurologist with complaints of persistent headache and diffculties with memory and attention “worse now than right after the accident.” She tried to return to work 3 months after the accident but could not concentrate enough to be productive.
Review of medical records shows that she had minimal, if any, loss of consciousness at the accident scene, and she followed commands at the emergency room without apparent difficulty. Neurologic exam and head CT were normal. She is cooperative and fully oriented but appears upset about the difficulties she has experienced and occasionally complains of headache.
Three days later you receive a signed release of information from her attorney, requesting all records related to her examination.
In cases such as Mrs. M’s, the differential diagnosis often comes down to a somatoform disorder vs factitious disorder vs malingering, a decision that rarely seems as clear-cut as one might believe when reading the DSM-IV-TR. Particularly in litigation- or compensation-related situations, clinicians must make 2 fundamental judgments:
- Is the patient intentionally generating the symptoms?
- Are the symptoms plausibly related to neurologic injury or illness?
This article describes how symptom validity testing (SVT) as part of a comprehensive neuropsychological evaluation can help answer these questions. Inconsistencies in the way patients perform on SVT (Table)18-30 can provide “red flags” to possible embellishment of neurocognitive symptoms. We also offer recently developed guidelines for diagnosing malingering of neurocognitive dysfunction that may be more helpful than the DSM-IV-TR criteria.
Table
Performance consistencies in patients
who fail symptom validity testing (SVT)
| Consistency | Comment |
|---|---|
| 25% to 40% of patients seeking some form compensation for their injuries or illness fail SVT | This appears to hold true not only for ‘brain’ cases but also for ‘pain’ cases |
| Deficits are not exaggerated in a constant manner across tests of different abilities | Deficits most likely to be exaggerated are concentration, memory, weakness, and processing speed; may be due to assumptions about what ‘brain damage’ looks like |
| Patients failing SVT report greater levels of emotional distress, psychological maladjustment, and severity of neurocognitive difficulties on self-report measures | Patterns of exaggerated responses are not the same as those exaggerating psychopathology |
| Very few patients who fail SVT score significantly below chance | Below-chance responding is an insensitive criterion for identifying suboptimal effort, but this level of performance is quite specific; short of confession, below-chance performance on SVT is closest to an evidentiary ‘gold standard’ for malingering |
| Not all SVTs are created equal | Sensitivity and specificity vary, and measures may disagree when more than one is administered |
| Coaching makes a difference | Malingering subjects who are told which tests to look for and how to approach them are more difficult to discriminate from genuine patients |
| Invalid effort does not rule out a genuine neurologic injury or illness | Exaggeration can coexist with neurologically driven neurocognitive deficits; neuropsychologists who do forensic work encounter patients with documented injuries who fail SVT, sometimes in blatantly obvious or absurd ways |
| Source: References 1-13 | |
Why ‘gut feelings’ are fallible
Differential diagnosis of neurocognitive impairment is challenging. Some patients have normal neurologic examinations in all respects but cognition, such as those with early Alzheimer’s disease or recent concussion. Others may show significant neurobehavioral changes but normal results on neuroimaging (such as the rare patient in a coma after a traumatic brain injury whose head CT is read as normal). Thus, the absence of findings other than impaired cognition in a neurologic exam is not proof that a disorder is driven primarily by psychiatric or behavioral issues.
- rely on their training and intuition
- refer for psychological evaluation
- rely on traditional malingering measures in standard psychological tests, such as the Minnesota Multiphasic Personality Inventory-2 (MMPI-2).
The problem with this approach is its high error rate. Health care professionals do not discriminate poor effort from genuine neurocognitive impairment very effectively. Diagnostic algorithms routinely outperform clinical judgment, particularly when diagnostic parameters are relatively well understood.19