High Specificity of the Word Memory Test and Medical Symptom Validity Test in Groups with Severe Verbal Memory Impairment
By definition, false positives occur when an otherwise very easy symptom validity test (SVT) or effort test is failed because of cognitive impairment and not because of poor effort. Therefore, the highest rate of false positives will be found in those groups with the most severe cognitive impairment. For that reason, it is important to study people with severe impairment when evaluating the specificity of SVTs. Some people with various types of dementia, notably those with Alzheimer’s disease, suffer from severe impairment of memory and other cognitive abilities. In this study, patients with possible or probable dementia were tested with the Word Memory Test (WMT; Green, 2003; Green & Astner, 1995) and the Medical Symptom Validity Test (MSVT; Green, 2004). While some dementia patients failed the easy subtests of these instruments and had severe verbal memory impairment, they showed distinctive profiles of scores that have been reported to be characteristic of people with severe impairment. Using profile analysis, the WMT and MSVT achieved a specificity of 98.4% or higher in the patients of the current study. This suggests that there will be extremely low false positive rates using the same methods in people with relatively minor impairment of the type found in, for example, mild traumatic brain injury or depression.
Although non-organic hearing losses are relatively rare, it is important to identify suspicious findings early to be able to administer specific tests, such as objective measurements and specific counseling. In this retrospective study, we searched for findings that were specific ti or typical for non-organic hearing losses. Patient records from a 6 year period (2003–2008) from the University ENT Department of Bern, Switzerland, were reviewed. In this period, 40 subjects were diagnosed with a non-organic hearing loss (22 children, ages 7–16, mean 10.6 years; 18 adults, ages 19–57, mean 39.7 years; 25 females and 15 males). Pure tone audiograms in children and adults showed predominantly sensorineural and frequency-independent hearing losses, mostly in the range of 40–60 dB. In all cases, objective measurements (otoacoustic emissions and/or auditory-evoked potentials) indicated normal or substantially better hearing thresholds than those found in pure tone audiometry. In nine subjects (22.5%; 2 children, 7 adults), hearing aids had been fitted before the first presentation at our center. Six children (27%) had a history of middle ear problems with a transient hearing loss and 11 (50%) knew a person with a hearing loss. Two new and hitherto unreported findings emerged from the analysis: it was observed that a small air–bone gap of 5–20 dB was typical for non-organic hearing losses and that speech audiometry might show considerably poorer results than expected from pure tone audiometry.