Monitoring Disease Progression: The Benefits of Repeated Neuropsychological Assessment

Written by Elizabeth S. Gromisch, M.A.

When someone has been diagnosed with a degenerative neurological condition or has sustained injury to the brain, such as with a traumatic brain injury (TBI), there is often a concern about changes in cognition. In a degenerative condition such as Alzheimer’s disease (AD), a decline in cognitive functioning can be indicative of disease progression. Identifying disease progression is important not only in clinical settings, but research settings in which new treatments are developed.

In AD drug trials, MRIs of brain atrophy may be used as an outcome, as changes in the volumes of the right and left hippocampi would be associated with changes in memory. Previously, screening measures of cognitive and behavioral status, such as the Clinical Dementia Rating (CDR) and AD Assessment Scale (ADAS) have been used (Cummings, Gould, & Zhong, 2012), but along with other brief measures like the Mini-Mental State Examination (MMSE), they may not be the most reliable (but that is a topic for another blog post!).

Schmand et al.’s (2014) study compared MRIs as an outcome to a neuropsychological battery. If you are not familiar with a neuropsychological battery, it consists of several measures that assess different cognitive domains, such as memory, language, and executive functioning. These measures can be pencil and paper tests, though they can be administered through a computer. In addition to providing a more comprehensive picture of an individual’s cognitive functioning, neuropsychological tests can have stronger psychometric properties than screening measures (Schmand et al., 2014).

Participants in the study (N = 62) were patients at the Academic Medical Centre memory clinic in Amsterdam. They were between the ages of 50 to 85 and had cognitive complaints. At baseline, they underwent a neurological examination and were administered the CDR and MMSE. Participants then underwent a structural MRI scan and neuropsychological evaluation, which included measures of executive functioning, memory, verbal fluency, and effort. Two years later, they had a follow-up MRI and neuropsychological evaluation, with alternative forms of the tests used. With the MRI, they focused on the cortical thickness of the temporal lobe and atrophy of the hippocampus. They found when they used the neurologist’s diagnosis, the neuropsychological assessment was more responsive with patients with MCI and early dementia compared to the MRI. Another benefit found with using this brief neuropsychological battery, which takes about 45 minutes, is intervention trials in AD and mild cognitive impairment which can have a 50% smaller sample size.

Repeat neuropsychological assessment is often used in a clinical setting. For example, an individual who has sustained a TBI may have an assessment early on in the recovery period, and may undergo repeat testing a year later to track changes in cognitive status. However, there are concerns clinicians should keep in mind with repeat testing. A significant issue that may arise is the practice effect, in which an individual’s performance on the follow-up may be better due to previous exposure to the measure. This can occur even when the questions on the test are different or an alternative version of the test is used (Heilbronner et al., 2010). In the official position from the American Academy of Clinical Neuropsychology (AACN), they recommend “change as a measurable construction to be used to inform the clinical descriptive and diagnostic process…consideration may be given to the standard error of measurement for a test manual, empirical findings on the expected magnitudes of score increases over a particular interval, or other relevant research on test operating characteristics for the instruments employed in the neuropsychologist’s battery.”

References

1. Cummings, J., Gould, H., & Zhong, K. (2012). Advances in designs for Alzheimer’s disease clinical trials. American Journal of Neurodegenerative Diseases, 1, 205-216
2. Heilbronner, R.L., Sweet, J.J., Attix, D.K., Krull, K.R., Henry, G.K., & Hart, R.P. (2010). Official position of the American Academy of Clinical Neuropsychology on serial neuropsychological assessment: the utility and challenges of repeat test administrations in clinical and forensic contexts. The Clinical Neuropsychologist, 24, 1267-1278
3. IOS Press. (2014 February). Neuropsychological assessment more efficient than MRI for tracking disease progression in memory clinic patients. Accessed from http://www.iospress.nl/ios_news/neuropsychological-assessment-more-efficient-than-mri-for-tracking-disease-progression-in-memory-clinic-patients/
4. Schmand, B., Rienstra, A., Tamminga, H., Richard, E., van Gool, W.A., Cann, M.W.A., & Majoie, C.B. (2014). Responsiveness of magnetic resonance imaging and neuropsychological assessment in memory clinic patients. Journal of Alzheimer’s Disease, 40, 409-418