To the Editor — In 2020, the disparities experienced by Black Americans compared to white Americans were highlighted by the convergence of two events: the COVID-19 pandemic and the racialized killings of George Floyd and Breonna Taylor by white police officers. To better understand the disparities in the health impacts of these incidents, we need more research on the link between historical exposure to trauma and contemporary health among Black Americans.

The COVID-19 pandemic made the year 2020 unexpectedly traumatic for us all. Though millions of Americans experienced (and continue to experience) negative health, economic and social consequences of the pandemic, its impact on the Black community was extraordinary. Black Americans were disproportionately hospitalized and more likely to die from COVID-19. This was primarily because COVID-19 risk factors (for example, diabetes, cardiovascular disease, low healthcare access or being an essential worker) disproportionately affect Black Americans. Black Americans also suffered more negative mental health effects, reporting more depressive and anxiety-related symptoms as the pandemic unfolded (37.7% in 2020 and 44.5% in 2021) compared to white Americans (35.4% in 2020 and 39.8% in 2021)1.

At the same time, the community witnessed the racialized killings of George Floyd and Breonna Taylor by white police officers, and these injustices prompted Black Lives Matter (BLM) protests throughout the US. Racialized police brutality also had detrimental health effects for Black Americans, including on their mental health. One study demonstrated that there was a significant increase in the severity of depression and anxiety in the week following George Floyd’s death2. This increase was more pronounced in Black Americans than in their white counterparts. This is particularly concerning because one study discovered that mental health ailments were linked with COVID-19 mortality3, in line with other work that links mental health to disease outcomes for physical ailments. I contend that racialized police brutality puts all Black Americans, not only the immediate targets of single events, at increased risk of both physical and mental illnesses.

The disproportionate health-related effects of COVID-19 on Black Americans and the killings of unarmed Black people by white police officers cannot be divorced from the historical trauma, through slavery and centuries of oppression, that Black people have experienced in the US. Two of these historical injustices became salient for Black Americans in 2020. COVID-19 health disparities reminded many Black Americans of the Tuskegee syphilis study, during which Black men were deprived of effective care for syphilis from 1932 to 1972. Similarly, the murders of George Floyd and Breonna Taylor were reminiscent of slave patrols — armed and unarmed white civilians permitted by law to perpetrate violence against Black people. Many Black Americans were disappointed but at the same time unsurprised by the events of 2020, given the injustices they have suffered historically in the US healthcare and criminal justice systems.

Historical trauma theory posits that populations who have historically been subjected to long-term, collective traumas transmit these traumas to subsequent generations, leaving them with a higher prevalence of adverse health4. This theory has its empirical basis in work with Jewish and Indigenous populations that has shown increased risk for post-traumatic stress disorder, psychological distress and depression as a result of ancestral exposure to trauma5,6. There is evidence that exposure to pre-conception adversity is linked with epigenetic changes, social inequalities and parental psychological dysfunction that can be transmitted across generations to affect health outcomes4,7. However, research exploring these associations in Black Americans is largely theoretical.

Many of the adversities and illnesses that are linked to historical trauma and transmission across generations are those to which Black Americans are more susceptible today. They are at higher risk of dysregulated cardiovascular, immune, endocrine, nervous and metabolic systems, which result in physical and mental illnesses8. Greater exposure to discrimination and other adversities has also been linked to accelerated cellular ageing in Black Americans. It is of fundamental importance that researchers start to address the question of how historical trauma directly influences the health outcomes of Black Americans today. This research can, for example, use large-scale epidemiological data, or focus on circumscribed groups such as the descendants of the survivors of the Tuskegee syphilis study. Such research may reveal the need for health interventions and policies that incorporate and benefit multiple generations in a family.

To measure historical trauma, the Historical Loss Scale and the Historical Loss-Associated Symptoms Scale have been used in research with Indigenous populations9. For Black Americans, the African American Historical Trauma (AAHT) questionnaire10 has been developed. The AAHT examines the links among direct exposure to racism, memories of the adversities one’s ancestors suffered, and levels of affective, cognitive and attitudinal indicators of historical trauma. It has demonstrated adequate internal consistency and factorial validity but requires further testing. Research on the health implications of historical trauma in Black Americans is possible and needs to be conducted. The body of literature that develops from studies on this topic will help to empirically establish the potentially substantial function of historical trauma in Black health and racial health disparities in the US. As 2020 reminded Black Americans: history is not only in the past.