"good-old-days" bias: A prospective follow-up study to examine the preinjury supernormal status in patients with mild traumatic brain injury

Primary objective: Postconcussion symptoms (PCS) are common following mild traumatic brain injury (mTBI). A psychological misperception, the "good-old-days" bias, has been indicated as one of the influencing factors on symptom reporting after injury. To date, this response bias has only been examined in a small number of cross-sectional studies. This study thus prospectively evaluated the "good-old-days" bias in patients with mTBI. Research design: A prospective follow-up study. Method and procedures: Fifty-three patients with mTBI were recruited in this study. The PCS was evaluated by the modified Checklist of Postconcussion Symptoms (mCPCS) at 1 month post injury. Twenty-five patients were evaluated again at 3 months after injuries. In addition, 53 healthy participants were also evaluated for the PCS, and 23 of them underwent a second evaluation at 2 months after the first one. Main outcomes and results: Patients with mTBI showed significantly higher PCS reporting at 1 month post injury than healthy participants did, but not at 3 months post injury. Consistent with the "good-old-days" bias, patients remarkably underestimated their preinjury PCS at 1 month post injury. Interestingly, our results further revealed that this response bias diminished more at 3 months than at 1 month after mTBI. Conclusions: This study thus might be the first one to prospectively reveal the progression of the "good-old-days" bias in patients with mTBI.