Why Brain Injuries Change Personality: Anger, Withdrawal, and Everything In Between

Why Brain Injuries Change Personality: Anger, Withdrawal, and Everything In Between

When Personality Shifts After Brain Injury: Why Some Become Angry While Others Withdraw

After a brain injury, many survivors experience dramatic shifts in mood and personality. Some become easily angered or act out, while others retreat inward, feeling disconnected or emotionally flat. These changes can be confusing for families — but they’re rooted in real, physical changes within the brain.

How Brain Injuries Disrupt Emotional Control

The areas most responsible for regulating emotion, the frontal lobes, amygdala, and limbic system  are especially vulnerable during a traumatic brain injury (TBI).

When the orbitofrontal cortex or ventromedial prefrontal cortex are damaged, a person loses some ability to regulate impulses, leading to anger, aggression, or disinhibition. Conversely, damage to regions tied to social awareness and motivation can cause apathy, social withdrawal, or emotional blunting.

In one study of veterans with TBI, researchers found that aggression and violent behavior were most strongly linked to injury in the amygdala and frontal cortex, both key to impulse inhibition and empathy.[2]

Why Anger and Aggression Are Common

The REACT Study, a 5-year project funded by the National Institute on Disability, Independent Living, and Rehabilitation Research, found that even ordinary frustrations can trigger intense anger in people living with chronic TBI. This emotional dysregulation can strain relationships and lead to conflict if misunderstood.[3]

The Department of Defense Health Behaviors Survey also reported that TBI and PTSD frequently overlap, intensifying the risk of violent outbursts or aggression — especially when both conditions are present together.[4]

When the Brain Goes the Other Way — Withdrawal and Introversion

Not all emotional shifts appear as aggression. Long-term studies show that many survivors actually become less talkative, less social, and less expressive after injury. A 2016 study in the Journal of Psychosomatic Research found significant drops in Extraversion and Conscientiousness among adults after brain injury, meaning many become more inward-looking and less socially driven.[5]

Even mild changes in processing speed or energy can make socializing exhausting. According to clinicians at the Brain Injury Law Center, frontal lobe damage may cause flat expression, limited eye contact, and disinterest in conversation — often misread as personality change rather than a neurological symptom.[1]

The Brain Systems Behind Personality Change

Brain Area Common Effect When Damaged
Frontal Lobes Impulsivity, poor anger control
Amygdala Heightened anger or fear; blunted emotion
Prefrontal Cortex Loss of empathy, social withdrawal
Limbic System Difficulty interpreting emotions or stress

Supporting Someone Through Change

Personality change after TBI isn’t a reflection of who someone chooses to be, it’s the result of neurological injury and emotional exhaustion. Compassionate therapy, structured routines, and specialized rehabilitation programs can improve emotion regulation and social confidence over time.[7][3]

Families benefit from learning about acquired personality change — a clinical term describing when a survivor feels and acts differently after trauma. Recognizing that it’s neurologically driven helps shift the focus from frustration to empathy.

Trusted Resources

References (Select Sources):

  1. Brain Injury Law Center. “Frontal Lobe Damage Long-Term Effects” (2025)

  2. Epstein, N. et al. Traumatic Brain Injury and Related Antisocial Behavioral Outcomes (PMC, 2023)

  3. Hammond, F., Neumann, D. et al. REACT Study on Emotion Regulation in TBI (Jefferson Moss Rehabilitation Institute, 2025)

  4. RAND Corporation / DoD. Health-Related Behaviors Survey: Anger & Aggression in mTBI (Military Medicine, 2025)

  5. Leonhardt, A. et al. Big-Five Personality Changes After Acquired Brain Injury (Journal of Psychosomatic Research, 2016)

  6. Frontiers in Behavioral Neuroscience. “Neuropsychological Review of TBI” (2024)

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