Research
Research conducted in the Howlett lab has three major objectives:
- To determine how long-term exposure to low levels of circulating testosterone affects the heart and whether testosterone therapy is harmful or beneficial in the setting of aging.
- To explore the links between estrogen, aging and heart disease.
- To investigate how frailty affects the heart’s ability to function under normal conditions and during times when blood flow to the heart is reduced.
1. Testosterone
Heart disease increases with age in men and women as sex hormone levels fall. Since a women’s risk of heart disease goes up after menopause, there has been a lot of interest in the idea that estrogen influences heart disease. However, it is now clear that testosterone decreases with age not only during “manopause” in men, but in women too. Marketing campaigns focused on testosterone’s benefits have increased the use of testosterone supplements in older people. Our goal is to explore effects of low testosterone and testosterone supplementation on the heart.
2. Estrogen
Pre-menopausal women are less likely to suffer from heart disease than are men, but this advantage disappears with age. This suggests that sex hormones such as estrogen influence heart disease. Even so, we know very little about the effects of estrogen on the heart, in part because most laboratory studies still use only male animals. Our group is investigating the effects of estrogen on heart function.
3. Frailty
As anyone who has ever attended their high school reunion knows, people age at different rates. Because a person's actual age is not always the same as their biological age, some older adults are fit and others are frail. Frailty is a major health care problem, because frail people are often harmed by traditional medical care. Even so, we know very little about frailty and its effects on organs like the heart, in part because we have not had an animal model to investigate frailty and its potential treatment. The goal of our research is to understand how frailty affects the heart’s ability to function under normal and diseased conditions.