NIH — SSRIs, Mass Shootings, Violence: Can Brain Science Hunt Causation?

By DavdS 

There is a new [August 29, 2025] report in The Washington Post, RFK Jr. links SSRIs and mass shootings. What does science say?, stating that, “Robert F. Kennedy Jr. suggested that psychiatric drugs may have played a role in the Minnesota Catholic school shooting — a statement widely criticized as unsupported by science. SSRIs, or selective serotonin reuptake inhibitors, a class of medications widely used to treat depression, anxiety, and other mental health disorders, have been repeatedly criticized by Kennedy, who alleges they pose serious health risks. In his “Make America Healthy Again” report, he cites them as a contributing factor to chronic disease in children.

In interviews and public statements over the years, Kennedy has speculated that psychiatric drugs lead to mass shootings at schools. In an April interview with YouTuber George Janko, Kennedy said the National Institutes of Health should override medical privacy rules to determine whether mass shooters used SSRIs.

An analysis of Columbia University’s Mass Murder Database shows that the lifetime prevalence of antidepressant use for perpetrators of mass shootings over the past 30 years is lower than the average number for Americans as a whole at 4 percent and for all psychiatric medications it is 7 percent, according to researcher Ragy R. Girgis, lead author of a study that is under review for publication.

In comparison, antidepressants are some of the most widely used drugs on the market, with national surveys estimating that 11.4 percent of Americans 18 years and older were on them in 2023.

Serotonin is a chemical that helps transmit signals between parts of the brain that are responsible for mood, sleep and behaviors. Low serotonin has been associated with depression, anxiety, mood swings and other negative emotional and behavioral changes — including both with violence toward oneself in the form of self injury and suicide and violence toward others. SSRIs work by increasing serotonin.”

Brain Science 

How does the human brain work to certify that two different experiential processes are linked — or not? What is mechanism, in the brain, for the event of violence? How do SSRIs work to benefit some outcomes and result in others, as side-effects? How is any correlation definitive about the brain, if it cannot be matched, with causation — or say how the brain works?

What does it mean that serotonin is abundant somewhere [at synapses], at some point? Does serotonin work in isolation for whatever it is said to benefit? How can the brain be conceptually understood, based on empirical neuroscience, to accelerate mechanistic answers?

Serotonin If serotonin “helps transmit signals between parts of the brain that are responsible for mood, sleep and behaviors” then what builds mood, sleep and behaviors? This question means that if there is mood, as an experience, what architecture of the brain must be matched to result in that outcome? If serotonin can transmit signals between brain areas, how does serotonin encode the messages and why would serotonin be able to do so?

What else, aside from serotonin, does something similar in the brain? When serotonin does this for mood, sleep and behaviors, does serotonin do it alone? If there are other signals, what is their contribution? What does this mean towards understanding how SSRIs work and their side-effects?

How does the Brain structure what is experienced? 

Neuroscience has established that in all functions of the brain [for human experiences], electrical and chemical signals [of neurons] are involved. Simply, whenever neurons are said to be involved in any function, signals are always directly implicated. Also, when it is said that a part [or an area] of the brain is responsible for a function, most times, what is located there, are neurons — at work, with signals.

It is not like signals are transmitting messages across brain areas [that contain something else, aside from signals — and neurons.] Simply, signals in a brain area can transmit to other brain areas because signals are there too, mostly.

So, it is possible to postulate a model of how the brain works, with neurons and their signals. The model should answer how the brain organizes information. If good mood and bad mood are information, how do neurons [and their signals] structure to make them possible? Neuroscience has shown that neurons are often in clusters, so this can be used to postulate that signals are in sets or in loops.

What is the contribution of clusters of neurons to behaviors? What is the contribution of electrical signals, in sets? What is the contribution of chemical signals, in sets? What is the total contribution of all? Which two, among the three, are more closely collaborative? If serotonin is a part of a set, for a mood or behavior, how much does serotonin contribute, aside from other chemical signals and then electrical signals?

Neurons 

Neurons are cells. While they are structurally different from other cells, they exhibit several similarities with others. Their difference from other cells also includes their ability to have channels for signal transmissions. This, conceptually, could mean that they are platforms for signals. Or, they are like conduits for signals to operate.

It can also be interpreted as neurons being the carriages for signals. Because neurons are cells, and are unlikely to change shape, it does not appear, conceptually, that they are directly responsible for structuring behaviors, mood, sleep or other mind states. If this were the case, neurons [in clusters] would have to be respectively specific in structures because of every memory, emotion, feeling and other functions.

Since there are numerous experiences, it would be too complicated to have this. And, how would signals transmit summaries of information that neurons structured?

Electrical and Chemical Signals 

It is theorized here that electrical and chemical signals are the configurators — or the basis — of all functions [for human experiences] in the brain. This means that when there is a mood, or behavior or memory, what is responsible is a specific configuration of electrical and chemical signals, in sets, in clusters of neurons.

Also, the reason that signals can transmit messages is because they configured it. Everything involving signals play roles in outcomes, both during transportation and at the destination. This means that sets of signals are destinations, so transmission [of configurations] from one set to the next is also a factor in experiences.

Violence and Side-Effects

Progress in neuroscience — for psychiatry, neurology and psychopharmacology — would be to use electrical and chemical signals to explain every condition in the Diagnostic and Statistical Manual of Mental Disorders, Text Revision [DSM-5-TR].

So, every label has to be explained with signals. This means that whatever violence is supposed to be, or side effects, or behavior, mood and so forth, have to be explained with internal mechanisms. Correlations can be better debated when causation is at least ahead, conceptually.

The instance of violence is a combination of relays across sets of signals. It may be preceded by relays to the set of hate, or vengeance, such that — as the relays become consistent in those directions — relays for caution or consequences are attenuated. The relays to the sets for hate, may also prompt planning, until the violence is acted.

Simply, in sets of electrical and chemical signals, there are configurations to specify functions. Mostly, electrical signals transport [or relay] summaries of a set to others. Pathways between some sets are sometimes available and usable, unlike between others. This could make hate and violence related, conceptually.

While some substances may increase the paths to [the sets of] hate and those to violence, it may not always mean that substances have to be involved.

Establishing this concept, including with estimations of how side-effects result could be useful, as the future approaches.

AI Psychosis

AI chatbots are available and accessible, making users turn to them for much. However, what becomes of the mind, in instances of conversations with chatbots could be displayed as well, to understand how to prevent extremes that have been heard in recent times about violence and psychosis that may have involved those chatbots.

There is a recent [August 28, 2025] spotlight in WSJ, A Troubled Man, His Chatbot and a Murder-Suicide in Old Greenwich, stating that, “ChatGPT fueled a 56-year-old tech industry veteran’s paranoia, encouraging his suspicions that his mother was plotting against him. ChatGPT repeatedly assured Soelberg he was sane—and then went further, adding fuel to his paranoid beliefs. While ChatGPT use has been linked to suicides and mental-health hospitalizations among heavy users, this appears to be the first documented murder involving a troubled person who had been engaging extensively with an AI chatbot. Amid an arms race in which the biggest tech companies are raising and spending tens of billions of dollars to gain AI supremacy—in part by making their bots feel more human—they are also grappling with the ways their products can encourage delusional thinking, psychosis and other troubling behavior.