Depression and Brain Injuries

Depression occurs after brain injuries so frequently that screening for it should be common practice. It’s logical, to an extent. Who wouldn’t be sad, after a brain injury?

Sounds simple-it is- and it’s also inaccurate. To assume that the depression (which has a symptom list far longer than simple sadness) is caused simply by the psychological effects of the injury is a dangerous misconception. Could it be? Perhaps- having a brain injury is living with a list of things you can no longer do. But humans are resilient.

Life is difficult, and often tragic. To some extent, the wonder isn’t at the high rates of depression, it’s how low they are when we consider the state of human existence (which, arguably, is better than it has been for much of human history, at least within industrial nations).

The numbers: Mayo Clinic says that people who have had traumatic brain injuries (TBIs) are between 2 and 5 times more likely to suffer from major depression. Another source, says that half the people with TBIs will develop depression within the year of the injury, and 2/3rds of them will have it within seven years.

Why the wait? Compare the symptoms. While every brain injury is unique, there are common symptoms between the two. When the symptoms don’t improve, the diagnosis of depression should follow. I suspect that the numbers are on the low side- after all, not everyone gets the diagnosis, even if they qualify.

We don’t know all that much about how the brain works, not well enough to treat it when things go wrong. In a brain injury, they can go wrong at a neurochemical level. Some neurotransmitters rise (is it protective? In some cases, high amounts cause damage…) and other neurotransmitters fall. We don’t necessarily know why, or what the effects are. And, each brain injury is different. Each brain is different, to some degree.

What we do know is that a brain injury can damage neurotransmitter systems. Looking at just one- dopamine- studies show that the dopaminergic system is affected in a significant number of patients. What is the difference between a dopamine deficiency and clinical depression? Low levels of dopamine are associated with an incredibly long list of symptoms, varying on the cause of the deficiency; It shares symptoms with both Parkinson’s Disease, and Depression.

There’s a very real possibility that the link between depression and brain injuries is caused by the damage to the neurotransmitter systems within the brain.

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