Study: Early removal of ovaries may be linked to small increase in risk of Parkinson’s disease in later life

RELEVANCE

Most relevant for: Women considering risk-reducing removal of both ovaries.

It may also be relevant for:

• previvors
• healthy people with average cancer risk
• people with a genetic mutation linked to cancer risk

Relevance: Medium

Strength of Science: Medium-High

Research Timeline: Human Research

Relevance rating details

What is this study about?

This study looked at whether removing both ovaries increases the risk of Parkinson's disease later in life. It looks specifically at a woman’s age at the time of surgery to determine whether delaying surgery changes her level of risk. Note that when we use "women" we are referring to the sex assigned at birth.

What are Parkinson's disease and Parkinson-like disease?

Parkinson's disease and Parkinson-like diseases affect the brain and cause uncontrollable muscle movement. Experts think some forms of Parkinson's are caused by a change in how nerve cells work in the brain. The causes of other forms of Parkinson's are not known.

Parkinson's can affect balance and posture, the ability to talk, and facial expression. It can also lead to mental and behavioral changes, sleep problems, depression, memory difficulties and fatigue. Many Parkinson's symptoms affect quality of life. These symptoms get worse over time and are not easy to treat.

The lifetime risk of Parkinson's is about 3.3 percent. About 90,000 people in the US are diagnosed with this disease each year, at an average age of 70 years old. The risk of developing Parkinson's increases as you age. Rates for Parkinson's are higher in men than women.

There seems to be a genetic link to Parkinson's. You may be at higher risk of developing Parkinson’s if one or more of your family members has the disease. About 15 to 25 percent of people living with Parkinson’s have family members living with it too.

Why is this study important?

This study looked at how removing both ovaries before menopause affects a woman’s risk for Parkinson's later in life.

For women diagnosed with ovarian cancer, treatment includes removal of the ovaries and fallopian tubes. For women at high risk for ovarian cancer removal of the ovaries and fallopian tubes (called risk-reducing salpingo-oophorectomy or RRSO) reduces cancer risk and increases overall survival. Experts recommend this surgery as the most effective way to lower the risk for people with inherited mutations that are linked to ovarian cancer.

The authors noted women’s ages at the time of ovary removal and whether they took estrogen after surgery. Data from this study may help premenopausal women who are considering removal of their ovaries to decide on the best time to have risk-reducing prophylactic surgery.

Study findings

5,499 women participated in the study. Approximately half had their ovaries removed between 1950 and 2007 and half did not. No person who had their ovaries removed had cancer. The reason for surgery or whether any of the women had an inherited mutation linked to ovarian cancer risk was unknown. The research team looked at data from medical records over a long period to see how many people in each group developed Parkinson's. On average, participants were followed for 24 years.

• 82 of 5,499 (1.5% percent) women were diagnosed with Parkinson's:
  • 50 of 2,750 women (1.8%) had both ovaries removed.
  • 32 of 2,749 women (1.1%) did not have their ovaries removed.
• Participants with Parkinson's were diagnosed, on average, 26 years after their ovaries were removed or 28 years after joining the study if they had intact ovaries:
  • Women with ovaries removed were diagnosed with Parkinson's, on average, at age 72.
  • Women with intact ovaries who developed Parkinson's were diagnosed, on average, at age 75.
• Women in this study who had their ovaries removed (regardless of their age at the time of the removal) had a 1.9% higher risk of Parkinson's compared to women who did not have their ovaries removed.
  • This suggests that ovary removal slightly increases the lifetime risk of developing Parkinson's from 3.30% to 3.36%.
• The rate of Parkinson's among women who had their ovaries removed before age 43 was 3.7% higher than among women who did not have their ovaries removed.
  • This suggests that ovary removal before age 43 increases the lifetime risk of developing Parkinson’s from 3.30% to 3.42%. This is also a very small increase in risk.
• Among women who had their ovaries removed at age 45 or younger, the risk of Parkinson's was lower in women who had their ovaries removed and then took estrogen through age 50 compared to women who did not. However, this result was not statistically significant.

What does this mean for me?

The amount of increased risk for Parkinson’s and Parkinson’s-like disease after ovary removal is small. The lifetime risk of Parkinson's disease is 3.3 percent in the general population. Ovarian removal may increase that risk to up to 3.4 percent. If you are premenopausal and your doctor has recommended that you remove your ovaries, you may want to weigh this possible outcome along with the other effects of surgical menopause against your risk for ovarian cancer. Although this study’s findings are not conclusive, estrogen may lower your risk of Parkinson's disease. If you decide to have your ovaries removed, talk with your doctor about the best timing for the procedure and the benefits and risks of hormone replacement after surgery.

Reference

Rocca WA, Smith CY, Rocca LG, et al., Association of premenopausal bilateral oophorectomy with parkinsonism and Parkinson disease. Journal of the American Medical Association Network Open; 2022; 5:10. Published online October 26, 2022

Disclosure: FORCE receives funding from industry sponsors, including companies that manufacture cancer drugs, tests and devices. All XRAYS articles are written independently of any sponsor and are reviewed by members of our Scientific Advisory Board prior to publication to assure scientific integrity.

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posted 5/3/23