Can skin cancers reduce the risk of getting Alzheimer’s disease?

Written by Surat Parvatam

The presence of skin cancer has been linked with a 61% reduced risk of Alzheimer’s disease.

In 2009, in an intriguing study, researchers found that the diagnosis of Parkinson’s disease was associated with a 27% reduced risk of cancer. This resulted in the ongoing quest to establish the link between neurodegenerative disorders and cancers. The curious link between the two is that cancer is linked to the uncontrolled growth of cells, whilst neurodegenerative diseases are linked to inappropriate cell death.

Since then, different neurodegenerative conditions have come under scrutiny, with studies showing that cancers had up to 43% lower risk of developing Alzheimer’s disease, but also that patients with Alzheimer’s disease were at a 69% lower risk of being admitted to hospital for cancer.

In a recent study, researchers at Northwestern University (IL, USA), explored if there was a potential link between skin cancer and Alzheimer’s disease. To investigate this, they searched the medical record data repository for patients aged 60–89 years admitted between January 2001 and December 2015. The selected patients were followed for at least 1 year after enlisting and had not been diagnosed with Alzheimer’s disease, malignant melanoma (skin cancer), or non-malignant melanoma.

After analyzing data from 82,925 patients and adjusting for variables that could affect the outcome (age, gender, race, cerebrovascular disease, peripheral vascular disease and diabetes), they found that the presence of skin cancer was associated with a 61% reduced risk of Alzheimer’s disease.

Why should the presence of skin cancer affect one’s occurrence of Alzheimer’s disease? Studies propose both biological and psychosocial reasons. Physically active people are shown to be at a lower risk for dementia, but staying outdoors for too long also exposes one to UV rays, which can increase the risk of certain cancers.

Cancers might also go undetected in patients with dementia who may not report the symptoms and doctors may not diagnose dementia in cancer patients as their treatment priorities are directed at cancer.

Although the study presents an interesting link between skin cancer and Alzheimer’s, further research is required to fully understand the relationship between them.