Diagnosis threat and underperformance: The threat must be relevant and implicit.

Introduction: The diagnosis threat (DT) phenomenon shows that, in some cases, reminding people with mild traumatic brain injury (mTBI) about their past neurological history diminishes subsequent cognitive performance. The aim of the present study was to investigate the role of personal relevance (i.e., domain identification) and type of threat (i.e., implicit vs. explicit) as moderating variables. We investigated intrusive thoughts as a potential mediator.

Method: Control (non-mTBI) and mTBI participants were recruited and completed a domain identification questionnaire. Under either an implicit or an explicit DT condition, they completed neuropsychological tasks assessing working memory, episodic memory, and executive processing, as well as measures of intrusive thoughts.

Results: As expected, the main results showed that, for working memory and episodic memory, high identifier mTBI participants scored worse in the implicit DT condition than in the explicit condition. The implicit DT condition also led high identifier mTBI participants to score worse than low identifiers for working memory. Conversely, the explicit DT condition led high identifier mTBI participants to perform better than low identifiers for both working and episodic memory. Unexpectedly, low identifier mTBI participants scored better on working memory tasks in the implicit DT condition than in the explicit condition. We found no evidence of mediation by intrusive thoughts.

Conclusions: Domain identification and the explicit or implicit nature of the DT must be taken into account, as they can impact mTBI participants' cognitive performance. This study suggests the influence of DT as a factor biasing neuropsychological assessment.