One in three older blood cancer patients are likely to have cognitive deficiencies, research from the US suggests.

And the findings that cognitive impairment is associated with poor prognosis highlights the case for routine cognitive screening, say the authors of a US study published this week in JAMA Oncology.

In the study, 360 patients aged 75 and over from leukaemia, lymphoma and myeloma clinics at a tertiary teaching hospital in Boston were screened for executive function and working memory.

In total, 35% tested positive for executive dysfunction and 17% for impairment in working memory.

Impairment of working memory was associated with increased overall mortality (median survival of 10.9 versus 12.2 months).

Deficits in executive function were predictive of mortality in a subset of patients undergoing intensive treatment.

Cognitive impairment often went ignored in the oncology world, although it was already known to be associated with poor prognosis in patients with solid tumours, according to study authors led by Dr Tammy Hshieh from the department of medicine at Brigham and Women’s Hospital in Boston, Massachusetts.

“Understanding domain specific cognitive impairment may assist haematologic oncologists in tailoring their explanations, assessments and care delivery for older patients,” they wrote.

Specifically, a low CIB score with normal recall would point to deficits in executive functions such as planning, organisation and multitasking.

“These patients often seem cognitively intact but can have substantial difficulty following complex conversations and multistep commands, managing medications and appointments and driving safely to the cancer centre,” the researchers said

Such patients could benefit from written instructions, repetition and routine, they advised.

In contrast, patients with impaired working memory but without executive dysfunction or delirium may have Alzheimers disease or amnestic cognitive impairment.

“Affected patients often have more difficulty following even simple directions and retaining educational information and may be labelled as unmotivated or not health literate. Fortunately, this form of impairment may be more modifiable by cognitive rehabilitation or training strategies,” they said.

The findings supported routine use of domain-specific cognitive screening tools among older people with blood cancer, the authors concluded.