June is designated as PTSD Awareness Month, which concentrates on the impact of post-traumatic stress disorder among people who suffer mentally, physically and/or emotionally from a past trauma.It is a modern diagnosis commonly associated with combat veterans, first gaining prominence following the Vietnam War. But since then, psychologists and psychiatrists have expanded the diagnosis to include all victims of trauma who display the disease’s symptoms:• States of hopelessness• Reliving the traumatic moment• Nightmares of the event• Avoidance, physical decay• Emotional numbness• Sleep deprivation• Negative thoughts• Self-destructive behaviour• Trouble concentrating• An inability to form or maintain attachments to close friends or familyThe goal of PTSD awareness is to help victims realise their symptoms and learn about treatment options.As PTSD awareness has increased in recent decades, historians have also studied how people experienced the aftershocks of trauma, or how they identified its symptoms. The historical record shows how pervasive PTSD has been throughout history, while also providing insight into people trapped under similar conditions of oppression experiencing and expressing grief, sorrow or pain in vastly different ways.American history is rife with examples of oppression, but the institution of slavery was unique in its systematic denial of humanity to people of African descent based solely upon race. Formerly enslaved people have left narratives that provide vivid descriptions of the violent acts that caused them and their loved ones great trauma — trauma that didn’t abate over time.In 1841, Solomon Northup wrote of a woman named “Eliza”, whom he first met in a “slave pen” in Washington. Eliza had deep affection for her children, but she was inconsolable because she knew that their separation from one another was inevitable. Sleep was impossible for her, although she maintained her composure around white people.Eliza’s sorrows intensified when she and her children were taken to the slave markets of New Orleans, where speculators acquired capital by selling human chattel. There her son, Randall, was callously sold, and Eliza embraced him, cried and kissed him repeatedly and told him to “remember her”.But Eliza’s sorrows continued as she was soon purchased without her daughter, the event that completely broke her spirit. “Please master,” she screamed, “I can never work any if she is taken from me: I will die.” Eliza did not die in a physical sense until many years after these separations, but Northup writes that for the rest of her life she expressed signs of severe emotional trauma from which she never recovered. She mourned Randall and Emily day and night, often refusing comfort from even her closest friends, and Northup observed her speaking to her children as if they were present. He suggested that her heart broke from a “burden of maternal sorrow”, and it seems clear she was mentally and emotionally damaged.Eliza became feeble and emaciated, and she rarely completed her tasks to the slaveholder’s satisfaction. Not satisfying the plantation mistress inside the house, she was sent to toil in the field as a punishment. She became indifferent to her fate and was consequently sold to a cruel enslaver who “lashed and abused her most unmercifully”. Eventually, the slave owner bludgeoned her head to put her “out of misery”, but she lived in a vegetative state until she was found dead.Other narratives also hint towards the effects of PTSD among the enslaved. Frederick Douglass wrote of a white man named Edward Covey, who held a reputation as a “breaker”, meaning he beat, harassed and worked the enslaved to the point that they accepted their position and mounted no resistance to his orders. Although Douglass eventually recovered his mental faculties and would break free from his bondage, he notes that, for a time, Covey broke him “in body, soul, and spirit”. The mental and physical captivities of slavery consumed him. He became disinterested in his former activities of self-improvement — such as literacy — and for a time he was transformed from a man “into a brute”.Similarly, Josiah Henson recounted how his father was once a man “of amiable temper” and “considerable energy”, but his attitude changed after he was lashed 100 times and his ear was disfigured as a punishment for beating the overseer who sexually assaulted his wife. The multifaceted trauma of witnessing his wife’s sexual assault, realising he was legally powerless to protect her and carrying the scars of his punishment, caused his personality to radically change. Henson’s father became “morose, disobedient, and intractable”, causing his eventual sale to another slave owner in the Deep South.Collectively, the narratives of Henson, Douglass and Northup illustrate how enslaved people understood the aftershocks of trauma and how people might never recover from the debilitations of enslavement. This trauma that they and millions of others experienced didn’t just impact the victim, but spread throughout the broader community and rippled through the next generation.Historians can assess how slavery’s physical abuses directly impacted the victim’s psychological health and the methods through which anti-black violence has been extended across generations. Recapturing this history helps extend empathy and sympathy for those experiencing trauma, in the past and the present. And it also helps us to better contextualise how the historical connections between racism and PTSD demands addressing the mental health needs of black communities who continue to face anti-black violence throughout the United States. Indeed, the racist roots of American medical disparities come from slavery, including gynaecological racism, sleep deprivation and assumptions about pain tolerance. Neither Henson, Douglass nor Northup would recognise the acronym “PTSD”, but they did know trauma and how it destroyed them and so many people they loved.As the genesis of anti-black violence in the US, slavery’s violent legacies remain in the fabric of modern American life, as manifested through economic inequities, police brutality, vigilante violence and political marginalisation. And the trauma that coincides such violence remains. Indeed, the word “trauma” is often invoked in the discussions of police brutality that have dominated the past month.As the world viewed Minneapolis police officer Derek Chauvin press his knee into George Floyd’s neck for almost nine minutes, a manoeuvre that led to Floyd’s death, many black people relived their own experiences with violent racism. Just as Northup witnessed Eliza call for her stolen children in the presence of ignoble slave owners, black Americans witnessed Floyd call for his deceased mother as Chauvin’s fellow officers callously refused to help him. And just as Floyd’s death was felt across Africa and the diaspora, black people followed their ancestors in collectively mourning for Floyd and all the black lives taken by white vigilantes and police officers.If we assume PTSD afflicts only soldiers and combat veterans, we risk overlooking how the intractable racism of our society produces and reproduces the myriad traumas experienced in marginalised communities.• Tyler D. Parry is assistant professor of African-American and African Diaspora studies at the University of Nevada, Las Vegas