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Mental Health Disorders Common Following Mild Head Injury

Aug 16, 2023 | Mental Health, Trauma

A groundbreaking study conducted by Danish scientists has demonstrated a significant correlation between head traumas, such as concussions and skull fractures, and the subsequent risk of developing mental disorders. The study revealed that head injuries can increase the likelihood of certain mental disorders by up to 439 percent.

Largest Study of its Kind: Examining Head Injuries and Mental Disorder Risk

Led by Sonja Orlovska, MD, from the Psychiatric Centre Copenhagen, the study represents the largest study of its kind. It utilized national register data from over 1.4 million individuals born between 1977 and 2000, with follow-ups conducted until 2010. Among the study population, 113,906 individuals had been admitted to the hospital due to head injuries. Subsequently, four percent of these individuals were diagnosed with a mental disorder.

Findings and Increased Risk of Mental Disorders After Head Trauma

The researchers focused on the occurrence of depression, schizophrenia, bipolar disorder, and organic mental disorders. Comparing the risk of developing these disorders between the individuals with head injuries and the rest of the study population, they found that those with head injuries were:

  • 65 percent more likely to be diagnosed with schizophrenia.
  • 59 percent more likely to develop depression.
  • 28 percent more likely to be diagnosed with bipolar disorder.
  • 439 percent more likely to suffer from organic mental disorders.

The greatest risk of developing a mental disorder was observed within the first year after experiencing head trauma. However, even after 15 years, there remained a significantly increased risk.

Unraveling the Chicken-and-Egg Dilemma: Disorder or Head Trauma?

Orlovska expressed surprise at the notable correlation between head trauma and mental disorders, even after adjusting for confounding factors. The team attempted to address the issue of causality by investigating whether individuals admitted to the hospital with non-head-related injuries, such as a broken toe, also exhibited a higher risk of developing mental disorders. While a slight increase in risk was found, it was significantly lower compared to head traumas.

Comparing Risk Levels: Head Traumas vs. Other Injuries

Among individuals diagnosed with schizophrenia during the study period, 12 percent had previously experienced head trauma. Similarly, 11 percent of those diagnosed with depression and 10 percent of those diagnosed with bipolar disorder had a history of head injuries. For organic mental disorders, 27 percent of diagnosed individuals had previously suffered head trauma. The risk increase associated with head trauma far exceeded that of other injuries. For example, a person with a broken arm had a 16 percent greater risk of developing schizophrenia, while the risk increased by 65 percent for those with head trauma.

Factors Contributing to the Correlation: Inflammation and Neurotransmitter Disruption

The exact explanation for the correlation between head injuries and subsequent mental disorders remains uncertain. However, Orlovska suggests several possible explanations. Animal studies have shown that head trauma induces brain inflammation, increasing the risk of psychological symptoms. Injuries that damage specific brain areas can lead to the development of mental disorders associated with those regions. Additionally, diffuse injuries like concussions can disrupt the balance of neurotransmitters, which are vital for intercommunication within the nervous system, potentially contributing to the development of mental disorders.

Psychological Reactions and Effects of Head Trauma on Mental Health

In some cases, head injuries may occur in traumatic accidents, and the subsequent psychological and emotional reactions to the trauma could trigger the onset of a mental disorder. The loss of physical functions or abilities following head trauma may also have an impact on the psyche, leading to the development of mental disorders. While the study does not provide definitive explanations, it highlights the significant association between head traumas and subsequent mental disorders, emphasizing the importance of further research in this area.

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