# Head injuries and criminal behavior **URL:** \ **Category:** Great Debates\ **Created:** [August 13, 2025, 9:39am UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005 "2025-08-13T09:39:43Z")\ **Posts on this page:** 20\ **Page:** 3
**Author:** ![74westy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/74westy/32/3950_2.png) [@74westy](https://boards.straightdope.com/u/74westy)\ **Post date:** [August 20, 2025, 1:26pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/41 "2025-08-20T13:26:49Z")
> [@RivkahChaya](#): > > The idea was that the people in the control group had all experienced some sort of accident with a serious injury needing treatment, in order to eliminate the possibility that violent or criminal behavior in the head trauma group was the result of PTSD, or displaced anger. Or that people likely to become criminals are more likely to to get themselves injured which the poster I was responding to thinks could be the cause of the correlation. ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [August 20, 2025, 3:59pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/42 "2025-08-20T15:59:20Z")
Seems like an opportunity for careful experimental design. I mean, you could easily make the case that people who are greater risk takers and more aggressive are _both_ going to be more likely to be criminals as well as get head injuries. The devil is in the details of figuring out that relationship via experimentation. ---
**Author:** ![74westy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/74westy/32/3950_2.png) [@74westy](https://boards.straightdope.com/u/74westy)\ **Post date:** [August 20, 2025, 4:07pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/43 "2025-08-20T16:07:15Z")
Ok. So this study’s idea of careful experimental design was to use a control group of people who had had lower limb injuries but no head injuries. If that is not good enough to control for risk taking and aggression, what would a careful experimental design look like? ---
**Author:** ![RivkahChaya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rivkahchaya/32/8919_2.png) [@RivkahChaya](https://boards.straightdope.com/u/RivkahChaya)\ **Post date:** [August 21, 2025, 10:49pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/44 "2025-08-21T22:49:03Z")
I’m not so much advocating for the current study, as saying, “Hey! reminds me of this thing I read a long time ago, that I wish I could find again.” It wasn’t the one posted earlier: it wasn’t in _The New Yorker_; it was in something like _Discover_, or _Scientific American_. Some kind of serious science, but written for general readership-- not a professional journal. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [August 22, 2025, 10:54am UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/45 "2025-08-22T10:54:31Z")
You can’t diagnose it in living people, but autopsy clearly shows characteristic brain damage from CTE, and it’s not at all subtle. They showed us pictures of a normal brain, a CTE brain, and an Alzheimer’s brain, and it didn’t take any training to see that they were strikingly different. So there’s definitely a thing that can happen. ---
**Author:** ![Spice\_Weasel](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/spice_weasel/32/5435_2.png) [@Spice\_Weasel](https://boards.straightdope.com/u/Spice_Weasel)\ **Post date:** [August 24, 2025, 2:15am UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/46 "2025-08-24T02:15:10Z")
> [@74westy](#): > > Ok. So this study’s idea of careful experimental design was to use a control group of people who had had lower limb injuries but no head injuries. If that is not good enough to control for risk taking and aggression, what would a careful experimental design look like? The problem I’m having is that if you were abused as a child, you probably have a higher probability of both aggressive behavior and head injury, so how do you identify head injury as a casual factor independent from the psychological, physical and other neurological effects of abuse? The effects of abuse on a child are pervasive even in the absence of a head injury. In fact, I think it’s likely that even without a head injury, abused kids have a higher likelihood of aggressive behavior. But that’s what we have to prove, right? We have to compare the population of abused kids with a head injury to the population of abused kids without one, to kids that aren’t abused at all, and see what their relative levels of aggression are. But even then we have a problem! Because if your abuse resulted in a head injury, it was probably more severe than that suffered by kids who didn’t have one. (But maybe not! Because you can get a TBI just from getting slapped around a lot. It’s a puzzle.) ---
**Author:** ![Johanna](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johanna/32/8318_2.png) [@Johanna](https://boards.straightdope.com/u/Johanna)\ **Post date:** [August 28, 2025, 12:00pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/47 "2025-08-28T12:00:42Z")
> [@susan](#): > > How many non-murderers had a head injury in childhood? Anecdata: A great many people I know. My parents didn’t abuse me, but once my father accidentally caused me to fall from my full height so that I struck my forehead against a concrete floor when I was 6. When I was 11, a rock estimated at 2 kg of mass was thrown high in the air by a kid who couldn’t see me and it described a parabolic arc accidentally directly impacting my forehead. I got stitches there. Lucky the rock missed my glasses. Good thing I inherited a hard skull from my Irish ancestors. Also note that the center of the frontal bone, where I got my impacts, is a robust area of the skull that can withstand impact better than the sides. I’m nonviolent to the point of being vegetarian. I drive at the speed limit and signal every lane change. I am the singular of anecdote, so take that for what it’s worth. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [August 28, 2025, 3:37pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/48 "2025-08-28T15:37:01Z")
So you’re Johanna Anecdata. Not quite as catchy as Hannah Montana, but it’ll do. 😁 ---
**Author:** ![Fear\_Itself](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/fear_itself/32/19637_2.png) [@Fear\_Itself](https://boards.straightdope.com/u/Fear_Itself)\ **Post date:** [August 29, 2025, 3:04am UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/49 "2025-08-29T03:04:11Z")
I’ve been knocked unconscious five times by various blows to the head. I’ve never been arrested for violent behavior, nor am I prone to it in the least. ---
**Author:** ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)\ **Post date:** [August 29, 2025, 3:14am UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/50 "2025-08-29T03:14:34Z")
Not all men are sex offenders, but most sex offenders are men. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [August 29, 2025, 6:20am UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/51 "2025-08-29T06:20:17Z")
In fact, the vast majority of men aren’t sex offenders, and also, the vast majority of sex offenders are men. ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [August 29, 2025, 10:55am UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/52 "2025-08-29T10:55:56Z")
Conditional (Bayesian) probability has always been a tricky topic for laypeople. ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [August 29, 2025, 11:59am UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/53 "2025-08-29T11:59:59Z")
There’s a specific brain disorder that is caused by repeated blows to the head. [Chonic Traumatic Encephalopathy, or CTE](https://en.m.wikipedia.org/wiki/Chronic_traumatic_encephalopathy) It was first described in the medical literature in a clown, whose act was to be shot out of a canon. It’s fairly common in boxers, and was initially named for boxers, before getting the bland name it has today. It can be definitively diagnosed after death, via autopsy. Like Alzheimer’s disease, there’s no way to diagnose it for sure in a living person. It is characterized by misfolded tau proteins, and it develops similarly to mad cow disease, in that once the misfolding gets started, it can progress on its own, without further head trauma. Blows that stretch the spinal cord (as the brain bounces around) were suspected as causal, at least in one presentation i went to. It’s a real, well-defined disorder, but one whose prevalence is unknown. It’s mostly observed in athletes who suffer repeated blows to the head, from boxers to soccer players. It can cause violent impulses. (And other neurological problems, like poor memory and clumsiness.) I’m guessing this is the hypothetical link between being abused as a child and abusing your children. But surely learned behavior (with a normal brain) is also part of the story. ---
**Author:** ![RivkahChaya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rivkahchaya/32/8919_2.png) [@RivkahChaya](https://boards.straightdope.com/u/RivkahChaya)\ **Post date:** [August 30, 2025, 7:28am UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/54 "2025-08-30T07:28:27Z")
I think the ultimate conclusion in the first article I read back in the 90s was that “more research was needed.” But not as a cop-out-- as a genuine conclusion-- something is going on, and in bears scrutiny. My gosh, how I want to find that article. The new one is just a springboard to talking about the old one. ---
**Author:** ![Jackmannii](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/jackmannii/32/311_2.png) [@Jackmannii](https://boards.straightdope.com/u/Jackmannii)\ **Post date:** [August 31, 2025, 3:19pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/55 "2025-08-31T15:19:27Z")
> [@puzzlegal](#): > > You can’t diagnose it in living people, but autopsy clearly shows characteristic brain damage from CTE, and it’s not at all subtle. They showed us pictures of a normal brain, a CTE brain, and an Alzheimer’s brain, and it didn’t take any training to see that they were strikingly different. There remain [controversies](https://pmc.ncbi.nlm.nih.gov/articles/PMC6532781/) in diagnosing CTE, as there’s overlap with other neurodegenerative conditions, arguments over histopathologic features at autopsies and a paucity of data about incidence in the general population and correlation with clinical features. [http://academic.oup.com/braincomms/article/6/2/fcad314/7614163](http://academic.oup.com/braincomms/article/6/2/fcad314/7614163) It’s not the slam-dunk diagnosis news and sports media often make it out to be. How much phosphorylated tau protein makes a violent abuser or killer? ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [August 31, 2025, 4:04pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/56 "2025-08-31T16:04:11Z")
> [@scudsucker](#): > > I can see a possible route, but i can’t support it: > > Head injury → opiate addiction → junkie > > But mine was > > Head injury → given opiates → back to being a psychonaut Which is another thing that you could rule out by using people with other injuries as the control group, because people can be given opiates for any sort of painful injury. > [@Spice\_Weasel](#): > > The problem I’m having is that if you were abused as a child, you probably have a higher probability of both aggressive behavior and head injury, so how do you identify head injury as a casual factor independent from the psychological, physical and other neurological effects of abuse? You look at other people who have similar head injuries, but from non-abusive causes. ---
**Author:** ![Miller](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/miller/32/481_2.png) [@Miller](https://boards.straightdope.com/u/Miller)\ **Post date:** [August 31, 2025, 4:06pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/57 "2025-08-31T16:06:35Z")
> [@susan](#): > > How many non-murderers had a head injury in childhood? Anecdata: A great many people I know. I know a lot of people who smoke cigarettes and don’t have lung cancer, but that doesn’t mean that smoking doesn’t cause lung cancer. ---
**Author:** ![susan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/susan/32/17537_2.png) [@susan](https://boards.straightdope.com/u/susan)\ **Post date:** [August 31, 2025, 4:44pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/58 "2025-08-31T16:44:58Z")
True, but it also means that you can’t assume that everyone who develops lung cancer smoked. ---
**Author:** ![RivkahChaya](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/rivkahchaya/32/8919_2.png) [@RivkahChaya](https://boards.straightdope.com/u/RivkahChaya)\ **Post date:** [August 31, 2025, 4:58pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/59 "2025-08-31T16:58:14Z")
The guy in the original study was looking for a way to either help or reassure people who had been abused in regard to not abusing their own children. Is it too far-fetched to say to people who were never head-injured that they will be OK, but taking a parenting class never hurt anyone, and to people who _were_ head-injured, that they definitely should take parenting classes, and either remain in therapy while their children were at home-- or at least while they were young, if the parent was doing well, or join a 12-step group for abusive parents and people who did not want to become such? ---
**Author:** ![puzzlegal](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/puzzlegal/32/3827_2.png) [@puzzlegal](https://boards.straightdope.com/u/puzzlegal)\ **Post date:** [August 31, 2025, 5:13pm UTC](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005/60 "2025-08-31T17:13:24Z")
> [@susan](#): > > True, but it also means that you can’t assume that everyone who develops lung cancer smoked. That doesn’t follow logically. It is likely that you only develop mesothelioma if you have been exposed to asbestos or a small number of similar minerals. It’s also true that most people exposed to those minerals never develop mesothelioma. But essentially no one develops meso without exposure to those minerals. [Previous page](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005.md?page=2) [Next page](https://boards.straightdope.com/t/head-injuries-and-criminal-behavior/1022005.md?page=4)