Executive dysfunction in psychosis following traumatic brain injury (PFTBI)

Abstract

Introduction: Executive dysfunction is well established in patients with traumatic brain injury and in schizophrenia (SCZ). However, assessments of executive function in psychosis following traumatic brain injury (PFTBI) are limited and inconsistent, and often do not reflect the deficits demonstrated in patients with traumatic brain injury (TBI) or SCZ. We sought to determine the extent of executive dysfunction in PFTBI relative to three comparison cohorts. Method: Measures of executive function were administered to dually diagnosed patients with PFTBI (n = 10) including tests of mental inhibition and switching, processing speed, and attention: the Stroop Task, Trail Making Test (TMT), and the Attention subtest of the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS). Demographically comparable patients with TBI (n = 10), SCZ (n = 23), and healthy controls (n = 23) underwent an identical battery. Results: Significant executive dysfunction was evident in patients with PFTBI on all measures. Relative to all three comparison cohorts patients with PFTBI performed most poorly. Conclusions: These data present novel evidence of substantially impaired executive function across four task types in PFTBI and suggest that TBI and psychosis have an additive influence on executive function deficits. Treatment programs requiring substantial executive engagement are not suitable for patients dually diagnosed with PFTBI.

Keywords:

• Psychosis
• Schizophrenia
• Traumatic brain injury
• Executive dysfunction
• Neuropsychology

Notes

¹ Preliminary analyses indicated that the statistical assumptions of analysis of covariance (ANCOVA; i.e., conditions of random group assignment and group comparability on all potential covariates) were not met by this dataset (see Miller & Chapman, 2001).

² We note, however, that descriptively a higher proportion of relatives of the psychotic groups had received diagnosis of a psychotic disorder than relatives of the other two groups, and this is in accordance with the heritability literature in psychosis (e.g., McGuffin, Asherson, Owen, & Farmer, 1994; Must, Janka, & Horvath, 2011).

³ Data for these analyses are contained in the supplementary material for this article (See Tables 4 and 5).

⁴ Contrecoup injury refers to tissue damage diametrically opposite to the site of impact, where the brain has moved rapidly within the skull in response to the force of impact and caused damage to tissue absorbing the force. Of course the frontal lobes are also vulnerable to direct frontal injury.

Additional information

Funding

This work was supported by the Austin Hospital Research Foundation [grant number 2-1372].