Your Antidepressants Aren't Working. Could an Old Concussion Be Why?

You have done everything right. You saw a doctor, you started a medication, you gave it the weeks it needed to work, and when it did not, you tried another. Maybe a third. And still, the fog has not lifted. If that describes you, it is worth stepping back and asking a question that standard care often skips: is there something in your history that could explain why the usual approach keeps missing? For some people, the answer traces back to a moment they had almost forgotten. An old hit to the head. The kind where you got your bell rung, shook it off, and moved on with your life.

The hit you forgot about

Think back. A hard tackle in high school football. A car accident where your head snapped forward. A fall off a ladder or a bike. A blast during a deployment. A fight. At the time it may have seemed minor. You did not go to the hospital, or if you did, they told you to rest and sent you home. Years or even decades later, that event can still matter, because the brain does not always return quietly to where it was.

The research here is sobering but useful. People who have taken a bell-ringing hit are more than three times as likely to experience depression, and that elevated risk does not fade quickly. It can persist for years (Beaton et al., 2020, Frontiers in Neurology). Long-term follow-up work has found that roughly half of people who took such a hit are not fully back to their old baseline years later (TRACK-TBI, 5-year outcomes). This is not about weakness or willpower. It is about a physical event with a long shadow.

Why the usual medications may keep coming up short

Here is the part that connects the dots. Most first-line antidepressants work on serotonin. That system is a genuine driver of depression for many people, which is why these medications help so many. But depression is not one single thing running on one single system. When depression is linked to an old head injury, it may run on a different track altogether, one that involves glutamate, the brain's most abundant signaling chemical.

If your low mood is being driven by a system that serotonin medications were never designed to reach, then adjusting the dose or switching to the next pill in the same family may not move the needle much. This is not just a theory. A meta-analysis looking at antidepressants after a head impact found no significant difference from placebo (Foreman et al., 2019, J Head Trauma Rehabil). That does not mean medication is useless for everyone. It means that for this particular pathway, the standard tool may simply be pointed at the wrong lock.

The phrase "antidepressants not working head injury" describes a real and specific pattern, not a personal failing. When the driver of the depression sits on a different biological system, the usual key does not turn.

Signs worth paying attention to

A head-injury history rarely shows up as depression alone. It tends to travel with a cluster of quieter symptoms that people often chalk up to stress, aging, or just being tired. Taken together, they can be a clue that something physical is worth looking at:

• Sleep that never feels restful, or a sleep pattern that changed after the injury. Sleep disorders affect roughly 30 to 70 percent of people with a head-injury history.
• Low energy, low drive, or a flatness that antidepressants have not touched.
• Trouble with focus, word-finding, or short-term memory.
• Mood swings, irritability, or a shorter fuse than you used to have.
• Changes that hint at a hormonal shift, since up to about one in six people can develop a hormone deficiency after a hit (pooled prevalence near 16.8 percent).

None of these prove anything on their own. But when several show up together in someone whose depression has not responded to standard treatment, a careful clinician starts asking about old injuries.

Where glutamate comes in

This is where the science gets genuinely hopeful. Ketamine and its close relative esketamine act on the glutamate system rather than serotonin. Their effects can be measured in hours rather than weeks, and they appear to open a window of heightened neuroplasticity lasting roughly 24 to 72 hours, a period when the brain is more able to form and strengthen connections (Zanos and Gould, 2018, Molecular Psychiatry).

An important clarity here. Spravato (esketamine) is FDA-approved for treatment-resistant depression. It is not approved for, and does not treat, a concussion or any head injury itself. A history of getting your bell rung is a risk factor that helps explain why depression became treatment-resistant. It is never, on its own, a reason to reach for ketamine. The point is simpler and calmer: if your depression may be running on the glutamate system, then a treatment that works on that system deserves an honest look.

Why the right evaluation matters

Untangling all of this takes more than a symptom checklist. It takes someone who can look at your history and ask why standard care missed. That is the value of an evaluation at a clinic with neurology on staff. Neurology here is a diagnostic lens, a way of understanding what is driving your depression, not a promise of any particular outcome. Sorting out whether an old hit is part of your picture also matters for the long run, since a national registry has linked a history of head injury to a modestly higher long-term dementia risk, about 24 percent (Lancet Psychiatry). That is not a reason to panic. It is a gentle reason to understand your own story clearly.

One more thing, said plainly because it matters. Research has found elevated odds of death by suicide among people with a concussion history (Erlangsen et al., 2018, JAMA). If you are struggling with thoughts of harming yourself, you are not alone and help is available right now. You can call or text 988 in the United States to reach the Suicide and Crisis Lifeline, any hour of any day.

If you have tried the medications and the fog has not lifted, and somewhere in your past there was a moment when you got your bell rung, it is a connection worth exploring. A proper evaluation from a clinic that has neurology on staff can look at this, measure where you stand, and help you understand why standard care may have missed. Sometimes the most useful step forward begins with looking honestly backward.