There is increasing concern of the development of neurodegenerative diseases many years after sustaining a TBI due to the physiological changes that occur following injury. The Institute of Medicine (2009) has concluded that there is an association between moderate and severe TBIs with Alzheimer’s and Parkinson’s disease. Veterans that sustained a TBI were at an increased risk for Alzheimer’s disease and dementia (Plassman et al. 2000). In individuals over the age of 55 years, this pattern was present for even a single presentation of a moderate to severe TBI (Gardner et al. 2014). Furthermore, individuals that sustained a TBI were also at an increased risk for Parkinson’s disease, particularly with multiple TBIs (Goldman et al. 2006). Additional research is needed.
In an attempt to examine the long-term impact of ABI, some of the most salient studies related to long-term outcomes were identified and reviewed. Participants’ follow-up periods ranged from three months to more than ten years. The studies included in the review were separated into two groups according to participants’ injury severity: 1) moderate to severe ABI (when both moderately and severely injured participants were included in the study) and 2) severe ABI (when only severely injured participants were included in the study). Studies were also separated according to three follow-up periods: 1) three months to two years, 2) three to five years, and 3) greater than five years. Results are summarized in the tables below.
The table below summarizes whether each long-term outcome study reported a positive or negative outcome regarding participants’ productivity, independence, and place of residence. Productivity outcomes were defined as positive if the majority (greater or equal to 50%) of participants were involved in any form of paid or unpaid labour, including volunteer work. If the majority of participants were not taking part in any of the aforementioned types of productive activity (e.g. they were retired) then it was considered a negative outcome. Independence was related to the level of supervision required. Positive outcome was noted as long as the majority of participants did not require institutional care or support. However, if the majority of participants did require this type of assistance it was deemed a negative outcome. Positive place of residence outcomes were defined as the majority of participants in the study not living in an institutional setting. Otherwise, it was considered a negative outcome. Positive trends and increases regarding productivity, independence, and place of residence were also viewed as positive outcomes.
In summary, although methodological differences between the various studies do not permit direct comparison, it is generally true that those who have moderate to severe ABI appear to fare better than those with exclusively severe ABI on the dimension of productivity in particular. Moreover, even those who have severe ABI might expect to have generally favorable outcomes with respect to return to independent living.