Growth Mixture Modeling of Depression Symptoms Following Traumatic Brain Injury.

Growth Mixture Modeling (GMM) was used to investigate the longitudinal trajectory of groups (classes) of depression symptoms, and how these groups were predicted by the covariates of age, sex, severity, and length of hospitalization following Traumatic Brain Injury (TBI) in a group of 1074 individuals (696 males, and 378 females) from the Royal Hobart Hospital, who sustained a TBI. The study began in late December 2003 and recruitment continued until early 2007. Ages ranged from 14 to 90 years, with a mean of 35.96 years (SD = 16.61). The study also examined the associations between the groups and causes of TBI. Symptoms of depression were assessed using the Hospital Anxiety and Depression Scale within 3 weeks of injury, and at 1, 3, 6, 12, and 24 months post-injury. The results revealed three groups: low, high, and delayed depression. In the low group depression scores remained below the clinical cut-off at all assessment points during the 24-months post-TBI, and in the high group, depression scores were above the clinical cut-off at all assessment points. The delayed group showed an increase in depression symptoms to 12 months after injury, followed by a return to initial assessment level during the following 12 months. Covariates were found to be differentially associated with the three groups. For example, relative to the low group, the high depression group was associated with more severe TBI, being female, and a shorter period of hospitalization. The delayed group also had a shorter period of hospitalization, were younger, and sustained less severe TBI. Our findings show considerable fluctuation of depression over time, and that a non-clinical level of depression at any one point in time does not necessarily mean that the person will continue to have non-clinical levels in the future. As we used GMM, we were able to show new findings and also bring clarity to contradictory past findings on depression and TBI. Consequently, we recommend the use of this approach in future studies in this area.

Service utilisation in a public post-acute rehabilitation unit following traumatic brain injury.

Traumatic brain injury (TBI) causes disability in a proportion of survivors across the spectrum of injury severity. Previous research suggests physical changes are the primary focus of rehabilitation, although cognitive, emotional and behavioural difficulties cause greater concern in the long-term. There is little information about services accessed by those with mild injuries, who often have no physical disabilities. This study investigated factors determining service utilisation in a population-based sample which included 52% mild injuries (PTA ≤ 24 hours). Chi-squares and t-tests were used to examine the impact of demographic, clinical, psychological and physical variables on referral of 175 TBI patients to clinical disciplines in a public, community-based rehabilitation facility in Hobart, Tasmania. Increased service intensity (total disciplines referred to), was associated with greater injury severity (p = .006) and previous TBI (p = .041). Less traditional rehabilitation services (nursing, psychology) received more referrals than traditional disciplines (physiotherapy, occupational therapy, social work). Referral to physiotherapy and occupational therapy was associated with greater injury severity, functional dependence, hospitalisation and older age. Referral to nursing, psychology and social work was associated with more post-concussion symptoms, younger age, anxiety, depression and assault-related injury. The large number of referrals to psychology strengthens the case for including it as a core rehabilitation discipline.

Impaired National Adult Reading Test (NART) performance in traumatic brain injury.

Some research suggests the National Adult Reading Test (NART) may be impaired by traumatic brain injury (TBI). To investigate this, a prospective, longitudinal study included 214 Australian TBI participants given the NART within 1 month post-injury, and at 6 and 12 months. TBI severity, age, education, sex, and mood (HADS) were examined, and significant improvement in NART- estimated full-scale IQ (FSIQ) was noted over time (p < .001). A three-way interaction of time, severity, and age showed younger and middle-aged mild TBI sub-groups improved significantly between 1 and 6 months post-injury, and the older sub-group between 6 and 12 months. In severe TBI, significant NART-estimated FSIQ improvement was noted only for the middle-aged and only between 6 and 12 months post-TBI. NART administration soon after TBI underestimated premorbid IQ, with a complex relationship between time post-injury, severity, and age. Participants with a longer education had higher NART FSIQs, although those with less education gained more IQ points between initial and 6 months assessments suggesting higher initial NART impairment. Regression equations predicted NART FSIQ at 6 (R = 0.813) and 12 months post-trauma (R = 0.792-0.845), their effectiveness being confirmed via cross-validation. No significant relationships were noted between NART-estimated FSIQ and mood variables, or evidence of significant gains in estimated FSIQ between 12 and 24 months post-injury.