Comparability of Neuropsychological Test Profiles in Patients with Chronic Substance Abuse and Mild Traumatic Brain Injury

Abstract

The purpose of this study was to compare 104 patients with acute uncomplicated mild traumatic brain injury (MTBI) to a sample of 104 patients from an inpatient substance abuse program to determine whether these patients could be differentiated by their pattern of relative cognitive strengths and weaknesses. Patients were matched on age, education, and gender. Eight cognitive measures were used that included tests of attention, memory, and processing speed. There were no statistically significant differences between the two groups on any of the cognitive measures. Using a two-step cluster analysis procedure (i.e., hierarchical and k-means analyses), seven common profiles were identified. There was no significant difference in the proportions of patients from the MTBI or substance abuse group in each of the seven profiles. These results show that patients with uncomplicated MTBIs could not be reliably differentiated from patients with substance abuse problems on these cognitive measures. This is of particular concern for clinicians evaluating the neuropsychological effects of MTBI in individuals with a comorbid history of substance abuse.

Keywords:

• Cluster analysis
• Mild traumatic brain injury
• Substance abuse

Notes

N = 208 (Uncomplicated MTBI, n = 104; Substance Abuse, n = 104). *percentiles. %Imp = percentage of patients with scores below the 10th percentile. LM-I = Logical Memory I, LM-II = Logical Memory II, VR-I = Visual Reproduction I, VR-II = Visual Reproduction II, DSPf = Digit Span Forward, DSPb = Digit Span Backward, TMTa = Trail Making Test Part A, TMTb = Trail Making Test Part B.

N = 208; (MTBI, n = 104; Substance abuse, N = 104); MTBI Profile 1 (n = 24), Profile 2 (n = 15), Profile 3 (n = 11), Profile 4 (n = 23), Profile 5 (n = 21), Profile 6 (n = 10); Substance Abuse Profile 1 (n = 24), Profile 2 (n = 19), Profile 3 (n = 16), Profile 4 (n = 11), Profile 5 (n = 19), Profile 6 (n = 15). MTBI = mild traumatic brain injury. SubAbuse = substance abuse. *Highest correlations.

N = 208. LM-I = Logical Memory I, LM-II = Logical Memory II, VR-I = Visual Reproduction I, VR-II = Visual Reproduction II, DSPf = Digit Span Forward, DSPb = Digit Span Backward, TMTa = Trail Making Test Part A, TMTb = Trail Making Test Part B. Standard deviations are not presented because these scores represent an “ipsative mean score”. Thus, the standard deviation is meaningless.

N = 208 (Mild TBI, n = 104; Substance abuse, n = 104); P = Profile.