Chemo brain is real, it’s common, and it is not you imagining things. The supplement most often sold for it was tested in a randomised trial during chemotherapy and did not improve cognition — but several things genuinely do help.
It’s common and documented. Chemotherapy-related cognitive impairment affects up to 75% of breast cancer patients during treatment, with 35% experiencing persistent deficits afterwards. Problems with memory, attention and processing speed are the usual pattern.
Ginkgo biloba failed its randomised test. A trial of EGb761, 60 mg twice daily versus placebo, given during adjuvant chemotherapy to 166 women with breast cancer, found no improvement in neuropsychological performance or cognitive symptoms.
What does have support isn’t a supplement. Cognitive rehabilitation — a structured, therapist-led programme — showed the most consistent benefits, alongside exercise, cognitive behavioural therapy and Tai Chi/Qigong. And there is no high-level evidence for drug treatments; donepezil did not show benefit. 🧠
- It’s real, and you’re not imagining it
- How common it is
- The ginkgo trial
- The newer, weaker ginkgo study
- Why drugs haven’t worked either
- Cognitive rehabilitation: the strongest option
- Exercise, CBT and Tai Chi
- The safety issue with supplements during treatment
- Other causes worth ruling out
- Compensatory strategies that work
- What to ask your oncology team
- Frequently asked questions
- Your checklist
It’s real, and you’re not imagining it
Before any evidence, the thing worth saying plainly: this is a recognised clinical entity with a name, a literature and formal clinical guidance. “Chemo brain” is the everyday term; clinicians call it cancer-related cognitive impairment or chemotherapy-related cognitive impairment.
People describe losing words mid-sentence, re-reading the same paragraph, forgetting why they walked into a room, struggling to hold a phone number, finding it harder to do two things at once. The typical pattern involves memory, attention and processing speed.
Being told this is normal, or stress, or age, is a common experience — and it’s wrong. Professional societies publish guidance on assessing and managing it, which is not something that happens for imaginary problems.
That matters practically as well as emotionally, because being taken seriously is what gets you referred to the intervention with the best evidence.
How common it is
| Measure | Figure |
|---|---|
| Affected during treatment | Up to 75% of breast cancer patients |
| Persistent deficits after treatment | 35% |
| Typical domains | Memory, attention, processing speed |
Read those two numbers together and something useful emerges. Most people experience it during treatment; a substantial minority carry it afterwards. So for many, some recovery over time is the expected course — which is worth knowing when you’re in the middle of it — while for around a third it persists and deserves active management rather than waiting.
The ginkgo trial
Ginkgo biloba is the supplement most often marketed for this, and it was properly tested.
| Element | Detail |
|---|---|
| Design | Randomised controlled trial vs placebo |
| Participants | 166 women with breast cancer |
| Intervention | Ginkgo biloba (EGb761) 60 mg twice daily |
| When | During adjuvant chemotherapy |
| Neuropsychological performance | No improvement |
| Cognitive symptoms | No improvement |
This is about as directly relevant a test as you could ask for: the right population, the right timing, a standardised ginkgo extract, a placebo comparator — and it improved neither objective performance nor how people felt their thinking was.
That’s genuinely useful information. It means that if ginkgo hasn’t helped you, the problem isn’t that you took the wrong brand or didn’t persist long enough.
The newer, weaker ginkgo study
To be complete rather than one-sided: a more recent study of a different ginkgo preparation — ginkgo ketone ester — reported improved cognitive performance in chemotherapy-related cognitive impairment, with the intervention group showing around 23% higher memory scores than controls.
But note the design. That was a prospective cohort study, not a randomised placebo-controlled trial. Cohort studies can’t rule out the differences between people who take something and people who don’t — motivation, baseline health, other things they’re doing — which is precisely what randomisation exists to handle.
A randomised, placebo-controlled trial showing no effect and a cohort study showing a benefit is a very common pattern in supplement research, and it usually resolves in favour of the randomised trial. Randomisation is the tool that separates “this substance works” from “people who take this substance differ in other ways.”
It’s also a different preparation, so it isn’t strictly a contradiction. What it isn’t is a reason to override a negative RCT — it’s a reason for someone to run a randomised trial of the newer preparation.
Why drugs haven’t worked either
It’s worth knowing this isn’t a case of supplements failing while medicine succeeds. There is no high-level evidence supporting pharmacological treatment for preventing or treating cognitive impairment in survivors of non-CNS cancers. Donepezil — a drug used in Alzheimer’s disease — did not show benefit.
So nobody has a pill for this. That’s frustrating, and it’s also why the interventions that do have evidence deserve more attention than they get.
Cognitive rehabilitation: the strongest option
This is the intervention to ask about by name, because it has the most consistent evidence and most people have never heard of it.
A structured, therapist-led group programme combining patient education with cognitive rehabilitation showed the most consistent benefits, improving several areas of thinking and memory.
What it actually involves: a tailored approach targeting specific, practical, everyday goals, using compensatory strategies to improve daily functioning. Not brain-training games — structured work on the specific things you’re struggling with, with someone who does this professionally.
Clinical guidance distinguishes two situations usefully: cognitive rehabilitation for people with objective cognitive impairment on testing, and Tai Chi or Qigong for people reporting symptoms. If formal testing has shown a deficit, rehabilitation is the targeted answer.
Exercise, CBT and Tai Chi
Alongside rehabilitation, the interventions with support are all things you do rather than things you take:
- Exercise. Consistently among the effective options — and it also helps fatigue, mood and sleep, all of which independently worsen thinking.
- Cognitive behavioural therapy. Effective, and particularly relevant given how tangled cognitive symptoms are with anxiety, low mood and sleep problems during and after treatment.
- Tai Chi and Qigong. Specifically noted as reasonable to consider for people reporting symptoms.
- Acupoint stimulation appears among the options studied.
None of these are exciting, and all of them are more supported than anything in a bottle.
The safety issue with supplements during treatment
This is the most important paragraph on the page. Supplements can interact with chemotherapy, targeted therapy, hormonal therapy and radiotherapy — affecting how drugs are metabolised, how well they work, or how toxic they are. Some herbal products, St John’s wort being a well-known example, alter the metabolism of a wide range of medicines. Certain antioxidants during treatment are debated precisely because some cancer therapies work partly through oxidative mechanisms.
Ginkgo specifically also affects bleeding risk, which matters when platelet counts may be low and procedures are planned.
Ask your oncologist or oncology pharmacist before taking anything — including vitamins, herbal products and teas. Take the actual packaging to the appointment. This is not defensive caution; interactions in this setting are real and consequential.
Other causes worth ruling out
Several things that worsen thinking during and after cancer treatment are separately treatable, and it’s worth having them checked rather than attributing everything to chemotherapy:
- Anaemia — very common with treatment, and it directly impairs concentration.
- Thyroid dysfunction, which some treatments can cause.
- Depression and anxiety, which impair memory and attention substantially and are treatable.
- Sleep disruption, including from medication, hot flushes or pain.
- Medication effects — anti-sickness drugs, painkillers, sedatives, hormonal therapies.
- Menopause, including treatment-induced menopause, which has its own cognitive effects.
- Vitamin B12 or vitamin D deficiency.
- Fatigue itself, which is not the same thing as cognitive impairment but looks similar from the inside.
Compensatory strategies that work
Compensatory strategies are what cognitive rehabilitation teaches — the practical scaffolding that reduces the load on the systems that are struggling. They’re not a consolation prize; they’re the mechanism.
- Write everything down in one place rather than several. One notebook or planner beats scattered notes.
- Use alarms and reminders for anything time-bound. Don’t rely on remembering to remember.
- Do demanding tasks when you’re freshest, and protect that window.
- One thing at a time. Divided attention is often the worst-affected domain, so multitasking costs disproportionately.
- Reduce background distraction — noise and interruption cost more than they used to.
- Establish routines and fixed places for keys, glasses, phone. Routine removes decisions.
- Break tasks into written steps.
- Tell people close to you what’s happening, so they can prompt without it feeling like a test.
Daily Planner Notebook
Compensatory strategies are the core of the intervention with the best evidence — and an external memory system is the first one
This is deliberately unglamorous. Cognitive rehabilitation works partly by teaching compensatory strategies — practical systems that carry the load the affected domain is struggling with — and a single external memory system is the foundation of that. The specific thing that matters is one place, not several: appointments, questions for your team, medication timings, symptoms, and the things you’d otherwise try to hold in your head. Scattered notes across a phone, sticky notes and three notebooks add cognitive load rather than removing it. Keep it with you, write things at the moment you think of them rather than later, and use it in appointments — writing questions beforehand and answers during is genuinely valuable when processing speed is affected. This supports rehabilitation; it isn’t a substitute for asking for a referral.
- One system, not several — scattered notes add load
- Write things as you think of them, not later
- Take it to appointments; write questions in advance
- Pair with alarms and reminders for time-bound things
- Ask your team for a cognitive rehabilitation referral
What to ask your oncology team
- “Can I be assessed for cancer-related cognitive impairment?” Naming it helps.
- “Is cognitive rehabilitation available to me, or can I be referred?” This is the intervention with the most consistent evidence.
- “Can we check my haemoglobin, thyroid function, B12 and vitamin D?”
- “Could any of my current medications be contributing?”
- “Is there an exercise programme suitable for me at this stage?”
- “Would psychological support help?” CBT has evidence here, and none of this is separable from mood and sleep.
- “Is this supplement safe with my treatment?” — before starting anything, with the packaging in hand.
Frequently asked questions
Is chemo brain real?
Yes. It’s a recognised clinical entity — cancer-related or chemotherapy-related cognitive impairment — with published clinical guidance on assessment and management. It affects up to 75% of breast cancer patients during treatment, with 35% experiencing persistent deficits afterwards, typically involving memory, attention and processing speed. If you’ve been told it’s just stress or age, that’s not consistent with the evidence, and being taken seriously is what gets you access to the intervention that works best.
Does ginkgo biloba help chemo brain?
The randomised evidence says no. A trial gave ginkgo biloba (EGb761) 60 mg twice daily or placebo to 166 women with breast cancer during adjuvant chemotherapy, and found no improvement in either neuropsychological performance or cognitive symptoms. A more recent study of a different preparation, ginkgo ketone ester, reported around 23% higher memory scores — but that was a prospective cohort study rather than a randomised placebo-controlled trial, so it carries considerably less weight. Ginkgo also affects bleeding risk, which matters during treatment.
Is there a medication for it?
Not currently. There is no high-level evidence supporting pharmacological treatment for preventing or treating cognitive impairment in survivors of non-CNS cancers, and donepezil — used in Alzheimer’s disease — did not show benefit. That’s genuinely disappointing, and it’s precisely why the non-drug interventions that do have evidence deserve more attention than they usually get.
What actually helps?
Cognitive rehabilitation has the most consistent evidence — a structured, therapist-led programme combining education with tailored work on specific everyday goals, using compensatory strategies. Clinical guidance suggests it for people with objective impairment on testing, and Tai Chi or Qigong for those reporting symptoms. Exercise, cognitive behavioural therapy and acupoint stimulation also appear among effective options. Ask your team by name whether cognitive rehabilitation is available or whether you can be referred.
Can I take supplements during chemotherapy?
Not without asking your oncology team first. Supplements can interact with chemotherapy, targeted therapy, hormonal therapy and radiotherapy — affecting drug metabolism, effectiveness or toxicity. St John’s wort is a well-known example that alters metabolism of many medicines, and certain antioxidants during treatment are debated because some cancer therapies work partly through oxidative mechanisms. Ginkgo also affects bleeding risk, which matters when platelet counts may be low. Take the actual packaging to your appointment and ask.
Will it get better?
For many people, yes. Comparing the figures — up to 75% affected during treatment and 35% with persistent deficits afterwards — suggests improvement is the common course, though that’s cold comfort while you’re in it. For the substantial minority in whom it persists, it deserves active management rather than waiting: assessment, a cognitive rehabilitation referral, and checking the separately treatable contributors like anaemia, thyroid function, mood, sleep and medication effects.
Your checklist
- Know it’s real and recognised — up to 75% during treatment, 35% persisting
- Ginkgo failed a randomised trial in exactly this population
- Weigh a negative RCT above a positive cohort study
- Note there’s no drug with high-level evidence either
- Ask for cognitive rehabilitation by name
- Consider exercise, CBT, Tai Chi/Qigong
- Never start a supplement during treatment without asking your team
- Note ginkgo affects bleeding risk
- Ask to check haemoglobin, thyroid, B12, vitamin D
- Review whether medications are contributing
- Use one external memory system, not several
- One task at a time; protect your best hours
- Tell people close to you what’s happening
Medical disclaimer. This article is general information and not medical advice. Do not start any supplement, vitamin or herbal product during or after cancer treatment without discussing it with your oncologist or oncology pharmacist — supplements can interact with chemotherapy, targeted therapy, hormonal therapy and radiotherapy, affecting how well treatment works or how toxic it is, and ginkgo additionally affects bleeding risk. Take the product packaging to your appointment. Cognitive symptoms during or after cancer treatment should be raised with your oncology team, who can assess for treatable contributors including anaemia, thyroid dysfunction, depression, sleep disturbance, medication effects and nutritional deficiencies, and who can advise on referral for cognitive rehabilitation.
Affiliate disclosure. Some links on this page are affiliate links. As an Amazon Associate we earn from qualifying purchases. We have not recommended any supplement here; the item we did recommend is a notebook, and it supports rather than replaces asking for a referral.
