Post-Conference Session Summaries

“The Reality of Cognitive Dysfunction in Cancer”

Instructional Session 1 presented Tuesday, April 24

In this instructional session, Wendy Vogel, RN, MSN, FNP, AOCNP, began by defining cognitive dysfunction (CD) as the loss of certain types of memories or defects in cognitive functions. CD is known by many names, including “chemo-brain,” memory loss, “chemo-fog,” or mild cognitive impairment. It is associated with chemotherapy, cranial radiation, stem cell/bone marrow transplant, biological agents, and hormone therapy and can occur before, during, and after therapy, even years later. The cause of CD remains undetermined, but several theories exist (e.g., the use of cytokines, direct cytotoxic damage from chemotherapy or brain surgery, preexisting psychological factors, vascular injury).

CD can have a significant impact on patients with cancer. In particular, patients experience quality-of-life issues (e.g., frustration, depression) and impaired social functioning. CD also has implications on treatment because forgotten details of patients' history may affect care and can affect adherence to treatment regimens.

CD can be a diagnostic challenge because so many areas can be affected. According to Vogel, patients typically do not present to a healthcare provider until the symptoms affect their quality of life. A number of signs and symptoms may indicate a patient is experiencing CD: defective executive functioning, loss of memory (particularly short term), impaired verbal ability, decreased fine motor skills, and behavioral and emotional changes. Diagnosing CD often is a “diagnosis of exclusion” because so many other causes (e.g., metabolic, metastatic disease) must be ruled out first.

Pamela Shapiro, PhD, turned the discussion toward factors affecting cognition. Normal aging can cause declines in memory in individuals as young as 35 years. Stress and depression have a negative association with cognition. Fatigue, illness, medication, and hormones also can affect cognition. However, research has shown that aerobic exercise has profound positive effects on cognition. Shapiro indicated that participating in aerobic activity three times a week for an hour is protective against future CD.

Dissociation, a common finding among patients with CD, is the incongruity between self-reports of cognitive deficits or decline and performance scores on measures of objective cognitive function and is not unique to patients with cancer. Individuals may exhibit perceived cognitive dysfunction (i.e., experience of cognitive loss) and have difficulty finding words, become lost in familiar surroundings, and struggle with concentration and memory. Objective cognitive function is evaluated through standardized tests of the cognitive function domains (i.e., language fluency, memory, executive function, and visuospatial processing) that measure impairment associated with traumatic brain injury, ischemic events, and neurodegenerative disease. Unfortunately, the measures are not without flaw. By emphasizing objective cognitive impairment, patients' subjective cognitive complaints may be underestimated when they fall within normal limits. Shapiro stressed that impairment should be determined based on age- and education-adjusted population norms, comparison with controls, and comparison with estimated premorbid IQ.

Research has focused on a number of regimens for their involvement in CD. Cisplatin-based chemotherapy has been found to modulate the blood-brain barrier, cause neuronal degeneration, and result in myelin thinning in animal studies. In a pilot study, patients with testicular cancer treated with cisplatin-based chemotherapy performed poorly on two measures of executive function, a color-word test, and a conditional exclusion test, whereas chemotherapy-naive men scored about a third of a standard deviation above the norms. Androgen-deprivation therapy was evaluated in a pilot study for its role in CD, and the control group, which did not undergo androgen-deprivation therapy, had lower performance scores on two measures of objective neurocognitive function.

Measures must be developed that are appropriate to specific populations. In addition, researchers should consider including stress as a predictor in models. “The bottom line is that clinicians may need to rethink the care provided to cancer survivors,” said Shapiro.