Rome Sick

They Know His Name, Not His Story

Caligula was a traumatized child, exposed to extreme depravity, and shaped by the assassinations of his family members. Caligula was an egotistical tyrant, a debaucherous psychopath, a frivolous fool. He was insane. He was immoral. He was a victim. He was a villain. 

Who was the real Caligula? Our historical sources on this controversial figure are limited. Of the authors that wrote about him, none were alive during his reign, and all were potentially biased by political interests. It’s hard to determine if the “little boot” was scarred by a traumatic childhood, afflicted by a mental illness, or simply an evil emperor. 

The medical information we have about him seems murky as well. Diagnoses that have been proposed have run the gamut of alcoholism, bipolar, depression, temporal lobe epilepsy, dementia, encephalitis, and syphilis. But the case of Caligula illustrates an important point about mental and neurological diseases: it’s rarely just one thing. The case of Caligula isn’t as clear cut as one would like. He is the traumatized child; he is the mentally afflicted young man; he is the self-centered ruler.

Who was the real Caligula: harmless horse boy or vengeful tyrant?

Trauma King

As Stefanie told us last week, Caligula did not have an ideal childhood. His father died, possibly poisoned by his jealous adoptive father, Tiberius. Seven years later, Caligula’s mother and brothers were exiled by Tiberius (and later killed), forcing him to move in with his great-grandmother. After she died, he was taken in by his grandmother. Eventually, Tiberius ordered Caligula to live with him. If the historical sources are to be believed, Caligula spent the next years being forced to partake in depraved sexual acts and pretending like Tiberius didn’t murder his entire family and ruin his childhood so that he wouldn’t also end up dead. Yep, sounds pretty traumatizing to me. 

Some academics suggest that Caligula’s behavior as emperor can be explained by the psychological effects of his early life experiences. Psychological and neuroscientific literature are filled with studies investigating the long-term effects of childhood stress. In fact, trauma is even defined in our trusty old friend the Diagnostic and Statistical Manual of Mental Disorders as “actual or threatened death, serious injury, or sexual violence.” The murders of Caligula’s family members and his forced participation in orgies seem to fit the bill.

As you can imagine, experiencing serious and chronic stress while your brain is still developing can have lasting consequences. It has been observed that children who experience trauma are more likely to go on to have mental health issues, such as addiction, PTSD, or depression. Childhood stress can also alter brain development, the immune response, and cognitive abilities.

Childhood trauma has wide-reaching consequences in the long-term.

One popular model of childhood trauma is the maternal separation stress paradigm. Researchers use this as a developmental rodent model of mood disorders, including anxious behaviors and increased alcohol consumption (yes, mice have been known to throw back a drink or two). Not only does this separation deprive pups of tactile and auditory cues from their mom that are important for development, it also activates the neuro-endocrine stress response. It is the release of stress hormones that is believed to mediate the long-term effects of childhood trauma. So, yes, Mom, leaving me at home to do yard work with Dad while you went grocery shopping literally was traumatic. 

Interestingly, the effects of this model depend on the duration of maternal separation as well as the age and sex of the mice used. A 2010 paper from researchers at the Universidad Autonoma de Puebla in Mexico isolated newborn male mouse pups for two hours per day for the first 12 days of their lives. The researchers later looked at three different brain regions involved in mood disorders in these mice before or after they went through puberty. They were particularly interested in looking at the structure of neuronal dendrites, which are the part of the cell that make connections with other cells and receive information. They measured three different aspects of dendrites: the number of dendrites within a region, the length of the dendrites, or how structurally complex they are.  The researchers found that maternally separated pups had shorter, fewer, or less structurally complex dendrites in all three regions. These changes imply altered signaling in these regions, which could potentially contribute to mood changes. Importantly, these differences in stressed versus unstressed pups were worse after puberty than before it.

This figure is quantifying the density of spines (B), the part of the dendrite that receives information, and dendrite length (C) in the hippocampus of mice before (35 days) and after (60 days) puberty. The gray bar represents mice that were separated from their mothers, and you can see that these mice had fewer spines and shorter dendrites only after puberty. Monroy et al., 2010. 

If we think about these data in terms of Caligula’s experiences, we can understand that his tumultuous childhood likely could have had biological consequences. Moreover, it’s not improbable that these effects would not have manifested themselves until he was a young adult. As you might remember from our Charles VI series, this is a particularly common time for young men to develop mental illness. Therefore, the idea that Caligula was shaped as a ruler by his trauma and that he was also mentally ill are not in conflict. However, the question of what exactly Caligula was ill with is a more difficult question.

Fire Away

In addition to his childhood increasing the likelihood of Caligula developing a mental disorder, his genetics also may have put him at risk. A 2017 paper analyzed historical records of the men in Caligula’s family and proposed potential mental illnesses and neurological diseases that might have afflicted them. Their final list included Parkinsonism, migraine, dementia, learning disorders, alcoholism, and depression. Intriguingly, of the 12 men they investigated, they found evidence for epilepsy in over half of them. 

The Julio-Claudian family may have been powerful, but they didn’t have the best pedigree. Camargo et al., 2010.

Epilepsy is a group of disorders characterized by seizures. A seizure is a sudden burst of electrical activity in the brain caused by an imbalance of excitatory and inhibitory communication between neurons. There are many different kinds of seizures, and they can be grouped by where they occur in the brain, how much of the brain they affect, and the effect they produce externally. While we usually think of someone laying on the ground, shaking uncontrollably, seizures can look very different. For example, someone may stiffen like a board, or even stare absently into space.

This figure shows electrical recordings (EEGs) from a normal patient and an epileptic patient at baseline or during a seizure. You can see that the frequency of activity increases during the seizure. Ebrahimpour et al., 2012.

The records we have seem to suggest that Caligula’s seizures were limited to his childhood. In fact, this makes sense. Childhood epilepsy is typically “grown out of” and is the form of epilepsy that scientists have found the most evidence of genetic inheritance for, explaining his family history. Most of these genetic risk factors are mutations in ion channels that bring charged particles in and out of neurons to maintain an appropriate electric charge. Disturbing ion transport can therefore lead to the changes in electrical activity that produce seizures. 

Caligula’s epilepsy may also be connected to his insomnia. One study from 2019 found almost 25% of adults with epilepsy experienced insomnia. In addition, while Caligula may have eventually stopped having seizures, childhood epilepsy increases the risk for social impairments and mental illness later in life. 

But what exactly caused Caligula’s abrupt personality change as an adult? Early onset dementia, alcoholism, bipolar disorder? Many theories have been proposed, but unfortunately, it’s hard to say for sure with the quality of sources available to us. However, the most notable detail we have is that Caligula became reckless, cruel, and egotistical after falling ill in October A.D. 37. Severe infection can induce a range of longer term neurological problems, one of them being encephalitis.

MRIs of normal and encephalitic brains. The bright white spots show active areas of inflammation. HHV-6 Foundation.

Encephalitis occurs when a virus infects the brain. The immune system, which is generally minimally active in the brain in order to prevent damage, is activated, causing massive inflammation. We don’t really know what symptoms Caligula experienced when he was sick, but encephalitis usually presents with fever, visual impairments, headache, and seizures (note: we don’t know whether Caligula had any seizures as an adult). It is noted that it took him about a month to recover from his illness, which is consistent with the recovery period for encephalitis. But even after patients recover from encephalitis, the inflammation and damage caused by the immune system can cause a host of lasting changes, including personality changes, behavioral problems, loss of emotional control, impairments in planning and problem solving, and depression. So maybe a simple virus can explain how Caligula went from respected leader to a financially irresponsible, romantically reckless, self-aggrandizing totalitarian. But maybe it had less to do with what was going on inside Caligula’s head and more to do with what surrounded him.

Sign of the Times

Some scholars have looked at Caligula’s behavior through a different lens; that of the time period in which he lived. Ancient Rome wasn’t exactly the moral capital of the world, and it can be argued that Caligula’s behavior “displayed only in an exaggerated fashion the weaknesses of his time – prodigality, immorality, hedonism, cruelty and extravagance in all things” (Sandison). Thus, it’s possible that some of Caligula’s behavior that we interpret as a result of mental illness actually reflected his culture. Marrying and divorcing four women in a row, for example, illustrates the sexual attitudes of the time. His trouble with personal finances were influenced by the luxury surrounding him. Stefanie pointed out last week that the cruelty of forced suicides were commonplace in ancient Rome. Even Caligula’s insistence that he be worshipped as a god could be explained by the great power he held and the widespread approval he got from his subjects. It has been suggested that his power to elevate others, like his sister, to the level of a deity, which past Roman leaders had done, led him to desire to be a god himself. Caligula certainly wouldn’t be the first leader in history to be corrupted by power (cough, Bill Clinton).

Caligula’s sexual indiscretions and violent streak weren’t exactly out of place in ancient Rome. Wikimedia Commons.

This theory doesn’t explain all of Caligula’s behavior, but it’s important to consider the greater context. Even today we often are tempted to point to a mental or neurological illness to explain behavior in leaders that we don’t agree with. “Trump has narcissistic personality disorder.” “Biden has dementia.” How much greater would the temptation for labeling be if you were ruled by a paranoid, cruel, hedonistic emperor? It can be more uncomfortable to admit that someone just genuinely isn’t a good person. But simply explaining away their behavior by assuming they are mentally ill not only minimizes the need for personal responsibility, but also stigmatizes people who do have mental illness or neurological diseases. The vast majority don’t become vengeful womanizers. As we talked about during the Henry VIII series, Caligula’s brain might explain the personality changes he experienced, but it’s not the full picture.

An Enigma, Wrapped in a Mystery, Inside an Enigma

To some extent, the truth about Caligula will always remain a mystery. His reputation as the “maddest” emperor in history makes for a juicy narrative, but probably isn’t accurate. Caligula’s shortcomings as a man and ruler were likely multifactorial. The combination of a traumatic childhood and the societal influences of Ancient Rome alone could explain some of his exaggerated behavior. While sources vary greatly in their depiction of Caligula’s madness, they seem to agree that he experienced an abrupt personality change after a serious illness. Many of his symptoms are consistent with viral encephalitis.

In reality, none of these factors operate in isolation. The most likely explanation to me is that Caligula’s early life stress put him at increased risk for mental illness later on, and the onset was precipitated by an infection. His odd behavior was influenced by the culture of excess that he lived in. This is the only way we can reconcile all of the records we have of Caligula; that he was scarred, mentally ill, and a product of his times. Don’t believe everything you read in the history books.


(n.d.). Retrieved from

Camargo, C. H., & Teive, H. A. (2018). Searching for neurological diseases in the Julio-Claudian dynasty of the Roman Empire. Arquivos De Neuro-Psiquiatria,76(1), 53-57. doi:10.1590/0004-282×20170174

DeBellis, M. D., & Zisk, A. (2014). Th Biological Effects of Childhood Trauma. Child and Adolescent Psychiatric Clinics of North America,23(2), 185-222.

Epilepsy: Impact on the Life of the Child. (n.d.). Retrieved September 8, 2020, from

Monroy, E., Hernández-Torres, E., & Flores, G. (2010). Maternal separation disrupts dendritic morphology of neurons in prefrontal cortex, hippocampus, and nucleus accumbens in male rat offspring. Journal of Chemical Neuroanatomy,40(2), 93-101. doi:10.1016/j.jchemneu.2010.05.005

Remaly, J. (2019, June 17). Insomnia symptoms correlate with seizure frequency. Retrieved from

Sandison, A. T. (1958). The Madness Of The Emperor Caligula. Medical History,2(3), 202-209. doi:10.1017/s0025727300023759

Sidwell, B. (2010). Gaius Caligula’s mental illness. Retrieved from

Zhang, D., Liu, X., & Deng, X. (2017). Genetic basis of pediatric epilepsy syndromes. Experimental and Therapeutic Medicine,13(5), 2129-2133. doi:10.3892/etm.2017.4267

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