Increasing Access to Underused Markers of Cognitive Decline: Development and
Validation of Intra-individual Variability in Cognitive Test Score Comparisons
 
   Lead Investigator:    Troy Webber
   Institution      :    Michael E DeBakey VA Medical Center
   E-Mail           :    troy.webber@va.gov
   Proposal ID      :    1526



   Proposal Description:
   Intra-individual variability in cognition involves short-term variations in cognitive functioning and may be conceptualized as dispersion-based IIV (IIV-d i.e., variability across a battery of tests) or inconsistency-based IIV (IIV-i i.e., variability within a test). While several studies have linked IIV with mild cognitive impairment and subsequent conversion to dementia in neurodegenerative disorders (particularly Alzheimer's disease and Parkinson's disease), clinical utility of this index is limited by inaccessibility of published data from reference samples of healthy-adults. The current study seeks to develop normative comparisons for IIV-d and validate these comparisons across a variety of neurodegenerative disorders with suspected predisposition for IIV. In particular, no study has shown how those with dementia with Lewy bodies (DLB) may exhibit IIV-d, despite well-established evidence that DLB is characterized by fluctuating cognition. We have several specific aims:     1) calculate robust norms for IIV-d,   2) validate normative comparisons of IIV-d in neuropathologically-confirmed and presumed neurodegenerative disorders (e.g., Alzheimer?s disease, Dementia with Lewy Bodies),  3) demonstrate the longitudinal effect of IIV-d in healthy adults on subsequent development of mild cognitive impairment and dementia, and 4), test the relationships between biomarkers that increase risk for cognitive decline and IIV-d. These data are expected to increase understanding of normal (and abnormal) variability in performances across a cognitive battery using a technique that captures subtle variations in cognitive performances. Findings from this project may increase access to this information for clinicians and researchers seeking to implement IIV-d in differentially diagnosing severity and etiology of cognitive impairment, as well as indexing risk for future cognitive decline.