What to explain
Tell the cancer team exactly what changed and when it began.
I have myeloma, and my thinking has changed. Can we check whether myeloma, anemia, high calcium, kidney problems, infection, treatment side effects, poor sleep, pain, low mood, or more than one cause explains it? Which results should we review now, what can I do safely, and when should I contact the cancer team again? I am forgetting recent information, losing track of tasks, thinking more slowly, or struggling to find words, and it is affecting daily life. I wrote down when this began, what treatment I was having, the days it is better or worse, and real examples of what became harder.
Questions to take in
Ask what needs same-day care, what can be checked now, and what should be followed.
- Does the timing fit myeloma, the treatment schedule, a steroid day, transplant recovery, infection, anemia, high calcium, kidney trouble, or more than one cause?
- Can we compare my current CBC, calcium, albumin, creatinine, estimated kidney function, electrolytes, glucose, and myeloma results with my earlier values?
- Could any cancer medicine, steroid, pain medicine, sleep aid, antihistamine, anti-nausea medicine, supplement, cannabis product, or interaction be making thinking or sleep worse?
- Would a short thinking test give us a useful starting score, or would my real-life examples and blood results answer the question with less effort?
- If the problem continues, would neuropsychology, occupational therapy, cancer rehabilitation, sleep care, pain care, or mental health support help me function more safely?
- What can I do safely with sleep, activity, food, fluids, reminders, and work while we investigate this? Do kidney, heart, bone, or infection risks change that advice?
- Which symptoms mean I should call the cancer advice line the same day, and which symptoms mean I should call emergency services?
- What should I save in My Fog, and when will we review whether the plan helped?
Checks chosen from the symptoms and treatment
Each check answers a different question about myeloma and thinking.
A CBC can show anemia and blood-cell changes. A CMP can show calcium, kidney, electrolyte, glucose, and liver results. A medicine review checks treatment and other drugs. A short thinking test records a starting score. A fuller neuropsychological evaluation is used only when the problem continues or affects daily safety and independence.
CBC + CMP blood test bundle
Checks hemoglobin for anemia, white cells for infection risk, platelets for bleeding risk, and calcium, albumin, creatinine, electrolytes, glucose, and liver markers. It is a group of results, not one score.
Read the test guideKidney Function Workup
Reviews creatinine, estimated kidney function, urine changes, fluid status, medicines, and earlier results. Myeloma protein, high calcium, dehydration, infection, and some medicines can affect the kidneys.
Read the test guideMedication Review
Checks whether cancer treatment, steroids, pain or sleep medicines, antihistamines, anti-nausea medicines, supplements, cannabis, alcohol, or interactions may be slowing thinking or disturbing sleep. Only stop treatment if the cancer team agrees.
Read the test guideBaseline cognitive assessment
Records a starting score for memory, attention, language, and thinking speed. The score cannot identify the medical cause by itself.
Read the test guideNeuropsychological evaluation
Measures several thinking skills and how they affect work, home, and independence. It may guide rehabilitation or support, but it is not needed for every person with cancer-related brain fog.
Read the test guideBefore the appointment
Bring the treatment dates, daily examples, medicines, and complete reports.
Write the date the thinking change began and whether it appeared suddenly, over several days, or slowly over weeks or months.
Bring three real examples of what became harder. These might include forgetting a treatment instruction, missing medicines, losing the steps of cooking, taking much longer to read, struggling to follow a conversation, or making mistakes with money or work.
Bring the full myeloma treatment schedule. Include each medicine name, dose, treatment day, steroid day, transplant date, CAR-T or bispecific treatment date, and any recent change. Speak with the cancer team before you stop or change cancer treatment.
Bring complete recent and earlier blood reports. The clinician can compare hemoglobin, white cells, platelets, calcium, albumin, creatinine, estimated kidney function, electrolytes, liver tests, glucose, and myeloma markers over time.
Bring the latest hematology or oncology letter, scan reports, bone marrow report if relevant, and the emergency contact plan from the cancer center.
For one or two treatment cycles, note when brain fog starts and how long it lasts. Add sleep the night before, pain, temperature, food and fluids, and the task that became harder. Do not delay urgent care so you can finish tracking.
Bring every prescription, over-the-counter medicine, supplement, cannabis product, nicotine product, and alcohol use. Include pain, sleep, allergy, nausea, and mood medicines.
Ask a trusted person what they have noticed and whether they can attend the appointment. Bring their examples only if you are comfortable sharing them.
One page with dates can show whether the problem starts after a steroid dose, during treatment, or after poor sleep. Add calcium, blood count, kidney, and infection results from the same dates.
How the doctor assesses this
Details that make myeloma or its treatment important to check
- The thinking change began after myeloma symptoms, a treatment change, a steroid dose, stem cell transplant, CAR-T, or bispecific treatment.
- Brain fog comes with thirst, frequent urination, constipation, nausea, muscle weakness, unusual sleepiness, or confusion that may fit high calcium.
- Brain fog occurs with severe tiredness, shortness of breath, dizziness, fever, infection symptoms, changed urine, swelling, new pain, or a worsening blood result.
Details that make sleep, mood, medicines, or another health problem important to check too
- The thinking problem was present for years before myeloma and has not changed with the cancer, treatment, blood results, sleep, pain, or medicines.
- Calcium, blood counts, kidney function, infection checks, and myeloma results remain stable while another diagnosed condition explains the change better.
- The problem improves after treating sleep apnea, depression, thyroid disease, vitamin B12 deficiency, pain, or another health problem.
- Sudden confusion, trouble speaking, weakness or loss of awareness isn't ordinary brain fog. Get checked urgently for stroke, infection, treatment toxicity, high calcium or another emergency.
What to understand before choosing care
What you and the cancer team need to decide
- Decide whether the change needs same-day cancer advice, a planned myeloma review, or emergency care.
- Review the dates beside treatment, steroid use, stem cell transplant, fever, sleep, pain, and blood results.
- Check anemia, calcium, kidney function, infection, medicines, sleep, pain, mood, and other treatable health problems.
- Before a long thinking test, record the task that became harder and the help you now need. This shows the daily change the test should examine.
- Agree on safe steps for daily life, who to contact, and when the thinking change should be reviewed again.
What the research found
What current guidance and 2025 to 2026 research say about myeloma and thinking.
Brain fog does not show whether myeloma is active. It can begin before, during, or after treatment. More than one cause may be present.
NCI myeloma criteria include specific disease findings. One example is hemoglobin below 10 g/dL. Others are creatinine above 2 mg/dL or creatinine clearance below 40 mL/min, and calcium more than 1 mg/dL above the laboratory upper limit when myeloma is responsible. These numbers help specialists define active disease. They are not personal brain-fog cutoffs or treatment targets.
A 2025 study followed 38 adults with myeloma before and 100 days after autologous stem cell transplant; 19 completed testing at one year. Average MoCA scores were 25.00 before transplant, 25.87 at 100 days, and 26.00 at one year, with no statistically significant average decline. The study was small, half the group completed the one-year test, and an average result cannot rule out a serious change in one person.
A 2026 ASCO Educational Book review says cancer-related cognitive impairment can affect memory, attention, thinking speed, and planning. There is no single accepted test cutoff, and self-reported problems may not match a brief test. Assessment should check daily function and treatable causes before deciding whether formal neuropsychology is needed.
Research on cancer-related cognitive rehabilitation supports practical strategies and selected rehabilitation programs. No medicine has strong evidence as a general treatment for brain fog in people with non-brain cancers. Treatment should match the measured problem and the person's cancer care.
How age, sex, and personal health affect the assessment.
Myeloma is mainly diagnosed in older adults. Current US SEER data show a median diagnosis age of 69, with the largest share of new cases between ages 65 and 74. Less than 1% of cases are diagnosed before age 35.
Older adults are more likely to have frailty, kidney disease, hearing or vision changes, sleep problems, and several medicines at the same time. The assessment should compare current function with the person's own earlier ability rather than blaming a new change on age.
A younger adult with confirmed myeloma still needs the same careful review. Work, parenting, fertility plans, and returning to study may change which daily effects and support matter most.
Myeloma is diagnosed more often in men than women, but brain fog is not measured with a separate male or female cutoff. The clinician should use symptoms, treatment, blood results, daily function, and the right reference data for any cognitive test.
US SEER data also show that myeloma is diagnosed more often in non-Hispanic Black people than in non-Hispanic White people. This population difference does not diagnose one person, but symptoms and abnormal blood results should not be dismissed because someone is younger than the typical patient.
If the answer is no
If your doctor will not order a stand-alone myeloma screening test
One symptom or routine blood result can't diagnose multiple myeloma. The National Cancer Institute uses several kinds of tests when the signs support them. These may include blood and urine protein tests, blood counts, kidney and calcium tests, bone marrow tests, and scans.
What changes the answer
- Bring the findings that raised concern. Include lasting bone pain, fractures, anemia, kidney changes, high calcium, repeated infections, weight change, and the full lab reports.
- Ask whether a myeloma protein test fits. Myeloma cells can make an unusual protein called M protein. Blood or urine tests look for it when other findings raise concern.
- Know that one abnormal protein result is not enough. It may take more blood, urine, bone marrow, or imaging tests to tell myeloma from another plasma-cell condition.
- Ask when to recheck unexplained results. Repeat blood counts, kidney tests, calcium, or a specialist review may be useful when an abnormal result lasts.
United States, United Kingdom, and Australia
Who to contact about Myeloma and Brain Fog.
US United States
Start with the myeloma team. Report the thinking change, treatment timing, fever, new neurological symptoms, and recent blood results. Ask whether you need same-day assessment or a planned review.
- Contact the hematologist, oncologist, transplant team, or cellular-therapy team about a new or worsening thinking change. Treatment changes belong with the cancer team.
- Primary care can help assess sleep, diabetes, thyroid disease, mood, vitamin B12 deficiency, and other health problems, but the cancer team should see the results.
- If the problem affects daily life, ask about oncology rehabilitation, occupational therapy, neuropsychology, social work, help at work, and insurance authorization.
UK United Kingdom
Call the haematology advice line when treatment may be involved. Give the treatment name and date, temperature, new symptoms, and whether the person is becoming confused, weak, breathless, or difficult to wake.
- Contact the haematology team, clinical nurse specialist, transplant team, or 24-hour cancer advice line for a new thinking change during treatment.
- Use the temperature threshold and infection instructions given by the hospital. When the cancer team has told you to call, call without waiting for a routine GP appointment.
- A GP can help check sleep, mood, thyroid, vitamin B12, and other conditions, while the haematology team reviews myeloma, treatment, calcium, kidney function, and blood counts.
AU Australia
Tell the cancer team what changed and when. Give the treatment date, blood results, fever or infection symptoms, and real examples of the thinking problem. Ask whether you need assessment today.
- Contact the haematologist, cancer treatment centre, transplant team, or immunotherapy team about a new or worsening thinking change.
- A GP or Aboriginal Community Controlled Health Service can help assess other health problems and arrange referrals, but cancer treatment changes stay with the specialist team.
- Ask the treatment centre or GP about occupational therapy, neuropsychology, cancer rehabilitation, Cancer Council support, and possible Medicare rebates.
Safety
Show how it affects daily life
- Record one task at a time: what you tried to do, how long it normally takes, what went wrong, and what help you needed.
- Use one calendar for treatment days, steroid days, blood tests, symptoms, and follow-up. Set alarms for medicines only after checking the schedule with the cancer team.
- Do difficult tasks when you can think most clearly. Do one thing at a time, write down the next step, and take breaks before you become tired.
- Ask for help with medicines, driving, cooking, money, stairs, or work equipment when a mistake could cause harm.
- Keep a regular sleep and wake time when treatment allows. Tell the team if steroids, pain, itching, nausea, or anxiety are keeping you awake instead of trying to manage it alone.
- Ask the cancer team what amount and type of activity is safe for your bones, blood counts, balance, and infection risk. Gentle movement may help some people, but myeloma bone damage can change what is safe.
Source checked
Sources behind this handout.
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National Cancer Institute: Plasma Cell Neoplasms Treatment, patient version
Source - 02
National Cancer Institute: Plasma Cell Neoplasms Treatment, health professional version
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National Cancer Institute: Cognitive Impairment in Adults with Cancer
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National Cancer Institute: Memory or Concentration Problems and Cancer Treatment
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National Cancer Institute SEER: Myeloma Cancer Stat Facts
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NHS: Treatment for Myeloma
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Cancer Research UK: Symptoms of Myeloma
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Cancer Research UK: Treating Problems Caused by Myeloma
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Myeloma UK: Mind and Memory Problems
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Healthdirect Australia: Multiple Myeloma
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Cancer Australia: Symptoms of Myeloma
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Cancer Council Australia: Changes in Thinking and Memory
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Cheung et al., ASCO Educational Book 2026: Assessment and management of cancer-related cognitive impairment (PMID 42208004)
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