A concussion is often described as a “mild” traumatic brain injury — but there is nothing minor about how it can affect your thinking, your mood and your day-to-day life. Whether it happened on a footy field, in a car, on a bike or in a fall at home, a knock to the head can leave you feeling foggy, forgetful, irritable and simply “not yourself”, sometimes for weeks or months afterwards.

In this article we look at what actually happens in the brain during a concussion, why the after-effects can linger, and how the cognitive and emotional changes people experience are real and explainable — not imagined. At Vitality Unleashed Psychology in Bundall on the Gold Coast, our Clinical Psychologists provide cognitive and psychological assessment and support for people navigating the aftermath of a brain injury, in person and via telehealth Australia-wide.

What is a concussion?

A concussion is a type of traumatic brain injury (TBI) caused by a bump, blow or jolt to the head, or by a hit to the body that causes the head and brain to move rapidly back and forth. It is classed as a “mild” TBI because it is not usually life-threatening, but that label refers to the immediate medical risk — not to the impact on your life.

Importantly, you do not have to lose consciousness to have a concussion. Many people are fully conscious the entire time and only realise something is wrong when the symptoms set in afterwards. Concussions are common in contact sports, motor-vehicle accidents, workplace incidents and everyday falls, and they can happen to anyone at any age.

What happens in the brain during a concussion

To understand why concussions affect thinking and mood, it helps to understand what is happening at a physical level. The brain is a soft, delicate organ that floats in cerebrospinal fluid inside the hard, bony skull. When the head accelerates and then stops suddenly — or is rotated quickly — the brain moves within the skull, stretching and twisting its delicate structures.

The mechanical injury

Brain cells (neurons) communicate through long, thin fibres called axons. During the rapid movement of a concussion, these axons are stretched and strained. This is sometimes described as a “shearing” force. The stretching disrupts the internal architecture of the cells and interferes with their ability to send signals cleanly. Unlike a bruise you can see, this is a microscopic, functional injury — which is one reason concussions often do not show up on a standard CT or MRI scan.

The neurochemical cascade

The mechanical stretching triggers a chain reaction at the chemical level. The affected neurons suddenly release a flood of neurotransmitters — the brain’s chemical messengers — and ions such as potassium and calcium rush across cell membranes in an uncontrolled way. If you would like a deeper look at how these chemical messengers shape mood and behaviour, our article on how neurotransmitters influence your behaviour and emotions explores this in detail.

To restore balance, the brain’s cells have to work overtime, pumping ions back to where they belong. This dramatically increases the brain’s demand for energy at exactly the moment when blood flow — and therefore the fuel supply — is often reduced. The result is an “energy crisis” in the brain: cells need more fuel than they can get. This mismatch is thought to be a major reason concussion symptoms can persist for days or weeks while the brain gradually returns to normal functioning.

Why the brain is vulnerable afterwards

During this recovery window, the brain is more vulnerable than usual. A second concussion before the first has healed can cause a much more serious and prolonged injury. This is why rest and a careful, graded return to activity — guided by a doctor — are so important, and why “playing on” after a head knock is never wise.

The cognitive after-effects

Because a concussion disrupts the way brain cells communicate and process information, the most common after-effects are cognitive — that is, they affect thinking. You might notice:

These changes can be frustrating and frightening, particularly if you rely on sharp thinking at work or study. It is worth knowing that for most people, these symptoms gradually improve. When they linger, a structured cognitive assessment can clarify exactly which areas are affected and help guide recovery.

The emotional and psychological after-effects

The neurological impact of a concussion is not limited to thinking. The very same brain systems involved in attention and memory are closely tied to emotion regulation, so mood changes are extremely common after a head injury. People frequently report:

There are two threads woven together here. First, the injury itself affects the brain regions that help regulate emotion, so the changes are partly neurological. Second, coping with an unpredictable, invisible injury — one that others may not understand — is genuinely stressful, and that stress compounds the mood effects. Some people also experience symptoms of post-traumatic stress after the event that caused the injury, such as a car accident.

None of this means you are weak or overreacting. These are recognised, well-documented consequences of how the brain responds to injury.

Feeling foggy, forgetful or flat since a head injury? A cognitive and psychological assessment can help make sense of it. Book Online (opens in a new window) · Submit an enquiry

Post-concussion syndrome: when symptoms linger

Most concussions resolve within a couple of weeks. For a minority of people, symptoms persist for a month or longer — a pattern sometimes called post-concussion syndrome. This can include ongoing headaches, dizziness, fatigue, difficulty concentrating, memory problems, sleep disturbance and mood changes.

When symptoms linger, it is easy to fall into a discouraging cycle: you push yourself to return to normal, become exhausted or overwhelmed, feel anxious about the lack of progress, and that anxiety in turn worsens the fatigue and fogginess. Understanding this cycle — and getting an accurate picture of what is actually going on cognitively — is often the turning point in recovery. Persistent symptoms always warrant review by your GP or treating doctor, who can coordinate the right care.

How cognitive and psychological assessment helps

One of the most useful things you can do when concussion symptoms persist is to get a clear, objective picture of your cognitive functioning. This is where formal assessment comes in.

What cognitive assessment involves

A cognitive assessment uses standardised, validated tests to measure specific thinking skills — memory, attention, processing speed, language and problem-solving — and compares your performance to what would be expected for someone of your age and background. Rather than relying on vague impressions of “brain fog”, it produces a precise map of which abilities are affected and which remain strong.

This kind of psychometric testing can be genuinely reassuring. Sometimes it confirms that your core thinking skills are intact and that fatigue or anxiety is driving the sense of fogginess — which changes the whole recovery plan. Other times it pinpoints specific difficulties, so support and rehabilitation can be targeted rather than guesswork.

Turning results into support

At Vitality Unleashed, cognitive assessment sits within our broader assessment and diagnosis services. Where you need documentation — for your GP, a specialist, an insurer, a workplace, or an education provider — we can provide clear, professional psychological reports that translate the findings into practical recommendations and reasonable adjustments.

Beyond assessment, our Clinical Psychologists offer individual therapy to help with the emotional side of recovery — managing the anxiety, low mood, irritability and adjustment challenges that so often accompany a brain injury. Evidence-based approaches such as Cognitive Behavioural Therapy (CBT) and Acceptance and Commitment Therapy (ACT) can help you pace your recovery, work with unhelpful thought patterns, and rebuild confidence.

How Vitality Unleashed can help

At Vitality Unleashed Psychology, our AHPRA-registered Clinical Psychologists support people recovering from concussion and other brain injuries through cognitive assessment, psychological reports and evidence-based therapy. We work alongside your GP and any other treating professionals, because concussion recovery is a team effort.

We see clients in person at our Bundall rooms on the Gold Coast and offer telehealth consultations Australia-wide, which can be especially helpful when fatigue makes travel difficult. Private fees apply, and eligible clients with a GP Mental Health Care Plan may access Medicare rebates — see our psychology fees page. Please note we do not bulk bill.

You don’t have to work out concussion recovery alone. A clear assessment can be the first step forward. Book Online (opens in a new window) · Submit an enquiry

Practical next steps for recovery

While you organise professional support, a few principles help most people recover well:

Frequently asked questions

Do you have to lose consciousness to have a concussion?

No. Many concussions occur without any loss of consciousness. Symptoms such as confusion, headache, dizziness, memory problems or “not feeling right” after a head knock can all indicate a concussion, even if you never blacked out.

Why doesn’t my concussion show up on a scan?

Concussion is largely a functional injury — it disrupts how brain cells signal and use energy, rather than causing visible structural damage. Standard CT and MRI scans often look normal after a concussion, which is why symptom assessment and cognitive testing are so important.

How long do concussion symptoms usually last?

For most people, symptoms improve within days to a couple of weeks. A minority experience symptoms for a month or more (post-concussion syndrome). Persistent symptoms should be reviewed by your GP, and a cognitive assessment can help clarify what is going on.

Can a psychologist help after a brain injury?

Yes. Psychologists can provide cognitive assessment to map how your thinking has been affected, psychological reports to support your care and any workplace or study adjustments, and therapy to help with the anxiety, low mood and adjustment challenges that commonly follow a brain injury — working alongside your medical team.

Helpful Australian resources

This article is general information only and is not a substitute for personalised advice from a qualified health professional. If you’re struggling, please reach out to your GP, a psychologist, or a support service. If you need to talk to someone now, call Lifeline on 13 11 14 or Beyond Blue on 1300 22 4636. In an emergency, call 000.