Grand Rounds

Is a Cancer Diagnosis Associated with Slower Memory Decline?

BACKGROUND AND PURPOSE:

Observational studies have identified that patients with a cancer history are less likely to develop Alzheimer’s (AD)
Data is limited for long-term cognitive trajectories comparing those with and without a cancer diagnosis
Ospina-Romero et al. (JAMA Network Open, 2019) compared long-term memory trajectories before and after cancer compared to age matched individuals without a cancer diagnosis

Population-based cohort study
Participants
- US adults from the Health and Retirement Study
- At enrollment: Born <1949 with no cancer history
Exposures
- Self-reported physician diagnosis of any cancer (not including nonmelanoma skin cancer) identified during biennial assessments
- Follow-ups performed up to 16 years (1998 to 2014)
Data analysis
- Model compared memory of
  - Those diagnosed with cancer during follow-up, before and after diagnosis
  - Those who remained cancer free during follow-up
Primary outcome
- Composite memory score using immediate and delayed word-list recall and proxy assessments

14,583 participants were included in the study
- Mean age, 66.4 years | 58.0% female
- Mean follow-up: 11.5 years
- During follow-up
  - Cancer diagnosis: 2250
  - No cancer diagnosis: 12,333
The rate of memory decline was slower for those with a cancer diagnosis vs cancer-free individuals (similar age)
- Rate of decline the decade before a cancer diagnosis: 10.5% (95% CI, 6.2% to 14.9%)
If diagnosis >75 years, mean memory function immediately before diagnosis was higher than that among similarly aged cancer-free individuals
A new cancer diagnosis was associated with a short-term decline in memory compared with memory before diagnosis
- However, after diagnosis, the rate of memory decline was slower vs those without a cancer diagnosis

In older people who developed cancer vs those without a cancer diagnosis
- Memory decline is slower
- Memory is better overall
This study provides some evidence cancer and AD “may be at opposite ends of a common pathological process”
Hypotheses include
- Inverse biological process that underlies these two diseases
  - Upregulation in cancer may be downregulated in AD or vice versa
Patients who survive long enough to get cancer have some underlying mechanism that may protect against AD

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