Prostate cancer treatment heightens risk of dementia

Prostate cancer patients receiving treatment with androgen deprivation therapy (ADT) are at increased risk of developing all-cause dementia or Alzheimer’s disease, a study has found.

Researchers looked at 100,414 men aged ≥66 years (median, 73 years; 84 percent white) who were diagnosed with locally advanced prostate cancer (cT1–cT4). None of them had a history of stroke, dementia, and use of psychiatric services.

In total, 37,911 men (38 percent) received ADT within 6 months of diagnosis, of whom 19,854 (53 percent) used ADT for >7 months. Compared with nonusers, ADT recipients were older (median age, 75 vs 72 years) at diagnosis, more likely to have received radiotherapy (64 percent vs 37 percent), have more comorbidities (≥2: 38 percent vs 31 percent), and have more advanced clinical tumour stage

Over 36 months of follow-up, 3,988 men were diagnosed with dementia, 1,797 developed Alzheimer’s, and 2,208 men utilized psychiatric services. These outcomes occurred more frequently among men exposed vs not exposed to ADT (dementia: 5.1 percent vs 3.3 percent; Alzheimer’s: 2.4 percent vs 1.4 percent; use of psychiatric services: 2.5 percent vs 2.0 percent).

Inverse-probability weighted Fine-Gray model showed that receipt of any pharmacologic ADT conferred a 17-percent higher risk of all-cause dementia (hazard ratio [HR], 1.17, 95 percent confidence interval [CI], 1.07–1.27), 23-percent higher risk of Alzheimer’s (HR, 1.23, 95 percent CI, 1.11–1.37), and 10-percent higher risk of psychiatric services use, although this was not significant (HR, 1.10, 95 percent CI, 1.00–1.22).

The risk was more pronounced among men with longer ADT exposure (≥7 months), which was associated with a 25-percent risk increase for all-cause dementia and 34 percent for Alzheimer’s.

The potential of a higher risk of dementia should be investigated further and weighed against the benefits of ADT in the present population, the researchers said.