Cognitive Problems

This section has been reviewed and approved by the PLWC Editorial Board, 02/05

Cognitive problems are difficulties in processing information, including such mental tasks as attention, thinking, and memory. Cognitive problems are also referred to as cognitive deficits or cognitive dysfunction. Cognitive problems occur in as many as 20% of people receiving standard dose chemotherapy. The problems can be very subtle or serious enough to cause difficulties at work, disrupt relationships, and make it difficult to complete daily activities.


Cognitive problems encompass difficulties in many areas, including:

  • Difficulty concentrating or paying attention (short attention span)
  • Memory loss or difficulty remembering things (especially problems with short-term memory)
  • Problems with comprehension or understanding
  • Problems with judgment and reasoning
  • Impaired arithmetic, organizational, and language skills (such as not being able to organize thoughts, find the right word, or balance a checkbook)
  • Problems performing multiple tasks (multitasking)
  • Behavioral and emotional changes, such as irrational behavior, mood swings, inappropriate anger or crying, and socially inappropriate behavior (disinhibition)
  • Confusion (delirium)

Of special note,"chemobrain," sometimes called "chemofog," is the term often used by cancer survivors to describe the cognitive problems experienced by some people after receiving chemotherapy. These people may experience long-term problems with mental skills such as memory, thinking, and concentration. People sometimes say that "chemobrain" feels like being in a mental fog.


Cognitive problems can be caused by many factors, including cancer, cancer treatments, medications, or other disorders:

  • Brain cancer

  • Other cancers that metastasize (spread) to the brain, such as breast or lung cancer
  • Chemotherapy, especially high-dose chemotherapy
  • Head and neck radiation or total body irradiation
  • Brain surgery, in which areas of the brain may be damaged or disrupted during biopsies or the removal of cancerous tumors
  • Hormone therapy and immunotherapy (including interferon [Roferon, Intron A] and Interleukin-2)
  • Medications, including some antinausea medications, antibiotics, pain medications, immunosuppressants, antidepressant/anti-anxiety medications, heart medications, and medications to treat sleep disorders
  • Infections, especially those of the central nervous system (brain and spinal cord), and infections causing a high fever
  • Other conditions or symptoms related to cancer or cancer treatments, such as anemiafatigue, stress, depressioninsomniahypercalcemia (high blood calcium), electrolyte imbalances, or organ failure
  • Nutritional deficiencies, especially iron, vitamin B, or folic acid deficiencies
  • Other brain or nervous system disorders unrelated to cancer


Cognitive problems caused by a reversible condition, such as anemia or an electrolyte imbalance, usually resolve after the condition is treated. Likewise, problems caused by a medication should go away after the medication is stopped. Problems related to cancer in the brain usually improve with treatment, but some symptoms may continue. Unfortunately, cognitive problems related to chemotherapy (such as "chemobrain"), radiation, or other cancer treatments can continue indefinitely. Management of these long-term cognitive problems may include:

  • Medications, including stimulants (methylphenidate [Ritalin]); cognition enhancing drugs, commonly used to treat Alzheimer's disease (donepezil hydrochloride [Aricept]); antidepressants; opiate antagonists (naltrexone [ReVia]); and sometimes hormone replacement therapy
  • Occupational therapy and vocational rehabilitation, to enhance daily living and job-related skills
  • Cognitive rehabilitation (also known as neuropsychological rehabilitation) and cognitive training, to help patients improve their cognitive skills and find ways to cope with cognitive deficits

Suggestions for coping with cognitive problems

  • Use a calendar or daily organizer to keep track of appointments, activities, and important dates (like birthdays).
  • Ask people to repeat information and write down new information (like names and phone numbers); use a tape recorder or take notes during conversations.
  • Post reminders and make lists.
  • Exercise your brain by doing brain-strengthening mental activities, such as solving crosswords or puzzles, painting, playing a musical instrument, or learning a new hobby.
  • Physical activity can increase mental alertness. Try walking, swimming, doing yoga, or gardening.

Cognitive deficits in children

Fortunately, approximately 70% of children with cancer can expect to be cured. However, cognitive problems can occur in both adults and children, and young children are especially susceptible to long-term (or late) cognitive deficits. These long-term deficits are most common in children who receive chemotherapy and/or radiation that is directed to the central nervous system (CNS), such as head and neck radiation, total body radiation, and chemotherapy delivered directly into the spine (intrathecal chemotherapy) or the brain (intraventricular chemotherapy). CNS-directed chemotherapy and/or radiation are most commonly used to treat CNS tumors, head and neck sarcomas, and acute lymphoblastic leukemia (ALL). Children who are treated before the age of five are most susceptible to cognitive deficits.

Long-term cognitive deficits can occur months or years after treatment ends and can continue into adulthood. Long-term cognitive deficits in childhood cancer survivors can include:

  • Decreased overall intelligence (lower IQ)
  • Learning disabilities
  • Decreased attention span and attention deficit disorders
  • Delayed development, including delayed social, emotional, and behavioral development
  • Lower academic achievement (especially in reading, language, and mathematics)
  • Decreased receptive and expressive language skills
  • Decreased nonverbal and verbal memory skills

Children may be helped with occupational therapy, speech therapy, behavior therapy, social skills training, cognitive rehabilitation, and medications (such as methylphenidate [Ritalin] for attention deficit disorders). Some children may need to learn new ways of learning in school or maintaining attention. Additional in-school options such as specialized reading and mathematics instruction, special education programs, and IEPs (individualized education programs) are also helpful. Because early intervention seems to offer the greatest benefit, it is important for parents to be aware of possible cognitive problems and to talk to their child's pediatrician or oncologist as soon as problems are suspected.

Additional resources

CancerCare: Chemotherapy Related Memory and Thinking Changes (Telephone Education Workshop,
July 12, 2005) Cognitive Dysfunction

More Information

PLWC Feature: Late Effects of Childhood Cancer

PLWC: Managing Side Effects

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