Shingles may significantly increase the risk of stroke and heart attack, particularly for people who suffer from the painful skin disease before the age of 40, according to a new study published in Neurology.

Shingles, also known as herpes zoster, is a painful rash caused by the varicella zoster virus, the same virus responsible for chickenpox. Even after the symptoms of chickenpox resolve, the virus remains dormant in nerve roots and can become reactivated at any time, causing shingles.

The study included 105,000 people who had had shingles and over 213,000 people who had not. Researchers found that shingles increased the risk of stroke, transient ischemic attack (TIA) and heart attack later in life, especially for adults who had shingles before the age of 40. Those aged 18 to 40 who had had shingles were 74% more like to suffer from a stroke, 2.4 times more likely to have a TIA and 50% more likely to have a heart attack later in life.

Older adults who had had shingles were also at increased risk – people over 40 were 15% more likely to have a TIA and 10% more likely to have a heart attack. Though it may occur at any age, shingles is more common in adults over 60.

The results held even when researchers controlled for other risk factors like smoking, high cholesterol and obesity.

Prior studies have also found a connection between shingles infection and increased stroke risk. The study’s authors said further study would be required to determine whether the shingles vaccine may effectively lower stroke and heart attack risk.