Cognitive tests strongly associated with demographic variables, not neurological findings
A recent retrospective study of cognitive assessment in traumatic brain injury patients found no clear pattern of cognitive ability associated with neurological impairment.
Cognitive assessment-in the form of tests such as the WAIS (in various versions) or the HRB (Halstead-Reitan Neurological Test Battery)-is often administered early to traumatic brain injury patients in order to determine cognitive functioning, diagnosis, and rehabilitation requirements. However, this study concluded that age and employment status was more strongly associated to cognitive assessment results than neurological findings, such as injury severity.
The researchers looked specifically for clear patterns of cognitive impairment -such as lowered cognitive results associated with lowered neurological results. And there were some sub-groups of cognitive testing did show such as association (such as processing speed). However, their overall finding was that demographics played a stronger role in cognitive assessment results than neurological factors.
Goldstein G, Allen DN, & Caponigro JM. A retrospective study of heterogeneity in neurocognitive profiles associated with traumatic brain injuries. Brain Injury. (April 2010).