Adversity accelerates aging at early ages, now measurable in real-time

 

Adversity in early life – whether preterm birth or socioeconomic disadvantage in childhood – accelerates aging, according to two recent studies, but underlying mechanisms remain unclear, and methods of investigation continue to evolve.

While one study used an established epigenetic clock to measure biological age among adults with extremely low birth weight, the other showcased a relatively new tool to measure pace of biological aging in disadvantaged children, suggesting that the metric may one day serve as a real-time measure of interventional efficacy.

These findings build upon previous studies that have demonstrated a correlation between biological age, also known as methylation age, and an increased risk of health problems later in life, according to Daniel A. Notterman, MD, professor of molecular biology at Princeton (N.J.) University.

“Finding that a person’s methylation age is greater than their chronological age has been taken as evidence of increased ‘biological age’ and perhaps a tendency to greater future morbidity,” Dr. Notterman wrote in a Pediatrics editorial. “Indeed, methylation age is advanced in association with a number of childhood and midlife adversities as well as morbidities such as atherosclerosis, cancer, and obesity.”
 

Extremely low birth weight associated with faster aging in men

For some individuals, accelerated biological aging begins at birth, or even in utero, according to Ryan J. Van Lieshout, MD, PhD, Canada Research Chair in the Perinatal Programming of Mental Disorders and the Albert Einstein/Irving Zucker Chair in Neuroscience at McMaster University, Hamilton, Ont., and colleagues.

The investigators conducted a study involving 45 extremely low birth weight (ELBW) survivors and 49 individuals born at normal birth weight. All participants were drawn from a longitudinal study conducted between 1977 and 1982 that assessed advances in neonatal intensive care. Controls were recruited at 8 years of age and matched with ELBW survivors based on family socioeconomic status, sex, and age. Follow-up continued through adulthood, allowing for the present trial to compare data from ages 8, 30, and 35.

Using samples of buccal epithelial cells, the investigators measured biological age with the Horvath epigenetic clock, the most commonly used tool of its kind, which measures cytosine-5 methylation at 353 cytosine-phosphate-guanine sites. Results were adjusted for a variety of covariates, such as smoking status, body mass index, number of chronic health conditions, and others.

Between groups, ELBW survivors trended toward older biological age, compared with adults born at normal birth weight (29.0 vs. 27.9 years), a difference that was not statistically significant. Further analysis, however, showed a significant sex-based difference between groups: Male survivors of ELBW, in adulthood, were almost 5 years biologically older than men born at normal birth weight (31.4 vs. 26.9 years; P = .01).

“[W]e provide preliminary evidence of a new link between ELBW and accelerated biological aging among men,” the investigators concluded.

In an accompanying editorial, Pam Factor-Litvak, PhD, vice chair of epidemiology at Columbia University, New York, wrote, “The findings are intriguing and open many questions for further study.”

Dr. Factor-Litvak noted that it remains unclear whether differences in biological aging were present at birth.

“[D]ifferences would provide evidence that accelerated aging begins during the in utero period, perhaps because of maternal undernutrition, stress, or another exposure,” Dr. Factor-Litvak wrote. “[R]eductions in chronic stress levels, which may begin for neonates with ELBW in utero and in the first hours of life, may provide an opportunity for interventions,” she added.

According to Calvin J. Hobel, MD, professor of pediatrics at Cedars-Sinai and professor of obstetrics and gynecology at University of California, Los Angeles, who has been studying preterm birth for more than 40 years, interventions may need to begin even earlier.

“The only way to prevent preterm birth is to do it before women get pregnant,” Dr. Hobel said in an interview. “The reason for preterm birth and poor fetal growth is the fact that the mother has early cardiovascular disease – unrecognized.”

Compared with women who give birth to full-term infants, women who give birth to preterm infants typically have increased blood pressure, Dr. Hobel said. Although these elevations in blood pressure are generally asymptomatic and not high enough to be classified as hypertensive, they impact umbilical artery vascular resistance starting at 28 weeks of gestation.

“In utero, [preterm infants] are programmed for increased vascular resistance and increased risk of cardiovascular disease,” Dr. Hobel said.

Regarding the effects of ELBW in men versus women, Dr. Hobel suggested that dissimilar neuroendocrine systems between sexes may protect females from adverse outcomes, although exact mechanisms remain elusive.
 

 

Measuring the impact of socioeconomic status on biological aging, now in real-time

A second study, by Laurel Raffington, PhD, of the University of Texas at Austin, and colleagues, evaluated the relationship between socioeconomic disadvantage in childhood and pace of biological aging.

To do so, they used the DunedinPoAm DNA methylation algorithm, a relatively new tool that was developed by analyzing changes in organ system integrity over time among adults with the same chronological age.

“Whereas epigenetic clocks quantify the amount of aging that has already occurred up to the time of measurement, DunedinPoAm quantifies how fast an individual is aging,” Dr. Raffington and colleagues wrote. “In other words, whereas epigenetic clocks tell you what time it is, pace-of-aging measures tell you how fast the clock is ticking.”

The investigators measured pace of aging in 600 children and adolescents (8-18 years of age) from the Texas Twin Project, “an ongoing longitudinal study that includes the collection of salivary samples.” The final dataset included 457 participants who identified as White, 77 who identified as Latinx, and 61 who identified as both White and Latinx.

The investigators evaluated pace of aging compared with family-level and neighborhood-level socioeconomic status, and tested for confounding by tobacco exposure, BMI, and pubertal development.

This analysis revealed that children experiencing socioeconomic disadvantage were aging more quickly than their peers, in terms of both family-level and neighborhood-level inequity (both levels, r = 0.18; P = .001).

Children who identified as Latinx aged faster than did those who identified as White only or White and Latinx, “consistent with higher levels of disadvantage in this group,” the investigators wrote. “Thus, our findings are consistent with observations that racial and/or ethnic socioeconomic disparities are an important contributor to racial and/or ethnic disparities in health.”

Higher BMI, greater tobacco exposure, and more advanced pubertal development were also associated with more rapid aging. After adjustment for these covariates, however, the significant correlation between socioeconomic disadvantage and rapid aging remained, the investigators noted.

“Our results suggest that salivary DNA methylation measures of pace of aging may provide a surrogate or intermediate endpoint for understanding the health impacts of [childhood] interventions,” the investigators concluded. “Such applications may prove particularly useful for evaluating the effectiveness of health-promoting interventions in at-risk groups.”

Still, more work is needed to understand exactly how socioeconomic disadvantage is associated with accelerated aging.

“Ultimately, not only longitudinal repeated-measures studies but also natural experiment studies and randomized controlled trials of social programs are needed to establish causal effects of social disadvantage on DunedinPoAm-measured pace of aging and to establish DunedinPoAm as a mediator of the process through which childhood disadvantage leads to aging-related health conditions,” the investigators wrote.

In his editorial, Dr. Notterman emphasized this point.

“[I]t is worth remembering that associations with either methylation age or pace of aging and health or longevity may represent the effect of an exposure on both the measure and the outcome of interest rather than a causal pathway that runs from the exposure (low socioeconomic status, adversity) to health outcome (i.e., cancer, vascular disease),” he wrote.

Paul Chung, MD, professor and chair of health systems science at Kaiser Permanente Bernard J. Tyson School of Medicine, Pasadena, Calif., and adjunct professor at the University of California, Los Angeles, called the findings “preliminary,” but noted that confirmation through further research could “fill in some really important gaps.

“Right now, to some degree, we’re at a little bit of an impasse,” Dr. Chung said.

Adverse childhood experiences are “associated very strongly” with mental and physical health issues, Dr. Chung said, “but we don’t know exactly why, and because of that, it’s really hard to come up with social policy solutions that aren’t anything but extremely sort of blunt-ended. We just say, ‘Well, I guess you gotta fix everything.’ And it’s a hard place to be, I think, in the field.”

Although the present study doesn’t resolve this issue, Dr. Chung suggested that the findings “really open the door to a lot of really exciting research that could have a lot of impacts on practice and policy.”

“Sometimes the only way to get people to pay attention enough to generate the level of excitement that would allow you to even do these sorts of studies ... is to generate some initial exploratory data that makes people perk up their ears, and makes people go, ‘Hey, wow, maybe we should be looking into this.’ ”

The study by Dr. Raffington and colleagues was funded by the National Institutes of Health and the Jacobs Foundation, with additional support from the German Research Foundation, Russell Sage Foundation Biology and Social Science Grant, the Canadian Institute for Advanced Research Child and Brain Development Network, and others. The study by Dr. Lieshout and colleagues was supported by Canadian Institutes of Health Research. Dr. Factor-Litvak and Dr. Notterman reported funding from the National Institutes of Health. All of the investigators and interviewees reported no conflicts of interest.

 

Adversity in early life – whether preterm birth or socioeconomic disadvantage in childhood – accelerates aging, according to two recent studies, but underlying mechanisms remain unclear, and methods of investigation continue to evolve.

While one study used an established epigenetic clock to measure biological age among adults with extremely low birth weight, the other showcased a relatively new tool to measure pace of biological aging in disadvantaged children, suggesting that the metric may one day serve as a real-time measure of interventional efficacy.

These findings build upon previous studies that have demonstrated a correlation between biological age, also known as methylation age, and an increased risk of health problems later in life, according to Daniel A. Notterman, MD, professor of molecular biology at Princeton (N.J.) University.

“Finding that a person’s methylation age is greater than their chronological age has been taken as evidence of increased ‘biological age’ and perhaps a tendency to greater future morbidity,” Dr. Notterman wrote in a Pediatrics editorial. “Indeed, methylation age is advanced in association with a number of childhood and midlife adversities as well as morbidities such as atherosclerosis, cancer, and obesity.”
 

Extremely low birth weight associated with faster aging in men

For some individuals, accelerated biological aging begins at birth, or even in utero, according to Ryan J. Van Lieshout, MD, PhD, Canada Research Chair in the Perinatal Programming of Mental Disorders and the Albert Einstein/Irving Zucker Chair in Neuroscience at McMaster University, Hamilton, Ont., and colleagues.

The investigators conducted a study involving 45 extremely low birth weight (ELBW) survivors and 49 individuals born at normal birth weight. All participants were drawn from a longitudinal study conducted between 1977 and 1982 that assessed advances in neonatal intensive care. Controls were recruited at 8 years of age and matched with ELBW survivors based on family socioeconomic status, sex, and age. Follow-up continued through adulthood, allowing for the present trial to compare data from ages 8, 30, and 35.

Using samples of buccal epithelial cells, the investigators measured biological age with the Horvath epigenetic clock, the most commonly used tool of its kind, which measures cytosine-5 methylation at 353 cytosine-phosphate-guanine sites. Results were adjusted for a variety of covariates, such as smoking status, body mass index, number of chronic health conditions, and others.

Between groups, ELBW survivors trended toward older biological age, compared with adults born at normal birth weight (29.0 vs. 27.9 years), a difference that was not statistically significant. Further analysis, however, showed a significant sex-based difference between groups: Male survivors of ELBW, in adulthood, were almost 5 years biologically older than men born at normal birth weight (31.4 vs. 26.9 years; P = .01).

“[W]e provide preliminary evidence of a new link between ELBW and accelerated biological aging among men,” the investigators concluded.

In an accompanying editorial, Pam Factor-Litvak, PhD, vice chair of epidemiology at Columbia University, New York, wrote, “The findings are intriguing and open many questions for further study.”

Dr. Factor-Litvak noted that it remains unclear whether differences in biological aging were present at birth.

“[D]ifferences would provide evidence that accelerated aging begins during the in utero period, perhaps because of maternal undernutrition, stress, or another exposure,” Dr. Factor-Litvak wrote. “[R]eductions in chronic stress levels, which may begin for neonates with ELBW in utero and in the first hours of life, may provide an opportunity for interventions,” she added.

According to Calvin J. Hobel, MD, professor of pediatrics at Cedars-Sinai and professor of obstetrics and gynecology at University of California, Los Angeles, who has been studying preterm birth for more than 40 years, interventions may need to begin even earlier.

“The only way to prevent preterm birth is to do it before women get pregnant,” Dr. Hobel said in an interview. “The reason for preterm birth and poor fetal growth is the fact that the mother has early cardiovascular disease – unrecognized.”

Compared with women who give birth to full-term infants, women who give birth to preterm infants typically have increased blood pressure, Dr. Hobel said. Although these elevations in blood pressure are generally asymptomatic and not high enough to be classified as hypertensive, they impact umbilical artery vascular resistance starting at 28 weeks of gestation.

“In utero, [preterm infants] are programmed for increased vascular resistance and increased risk of cardiovascular disease,” Dr. Hobel said.

Regarding the effects of ELBW in men versus women, Dr. Hobel suggested that dissimilar neuroendocrine systems between sexes may protect females from adverse outcomes, although exact mechanisms remain elusive.
 

 

Measuring the impact of socioeconomic status on biological aging, now in real-time

A second study, by Laurel Raffington, PhD, of the University of Texas at Austin, and colleagues, evaluated the relationship between socioeconomic disadvantage in childhood and pace of biological aging.

To do so, they used the DunedinPoAm DNA methylation algorithm, a relatively new tool that was developed by analyzing changes in organ system integrity over time among adults with the same chronological age.

“Whereas epigenetic clocks quantify the amount of aging that has already occurred up to the time of measurement, DunedinPoAm quantifies how fast an individual is aging,” Dr. Raffington and colleagues wrote. “In other words, whereas epigenetic clocks tell you what time it is, pace-of-aging measures tell you how fast the clock is ticking.”

The investigators measured pace of aging in 600 children and adolescents (8-18 years of age) from the Texas Twin Project, “an ongoing longitudinal study that includes the collection of salivary samples.” The final dataset included 457 participants who identified as White, 77 who identified as Latinx, and 61 who identified as both White and Latinx.

The investigators evaluated pace of aging compared with family-level and neighborhood-level socioeconomic status, and tested for confounding by tobacco exposure, BMI, and pubertal development.

This analysis revealed that children experiencing socioeconomic disadvantage were aging more quickly than their peers, in terms of both family-level and neighborhood-level inequity (both levels, r = 0.18; P = .001).

Children who identified as Latinx aged faster than did those who identified as White only or White and Latinx, “consistent with higher levels of disadvantage in this group,” the investigators wrote. “Thus, our findings are consistent with observations that racial and/or ethnic socioeconomic disparities are an important contributor to racial and/or ethnic disparities in health.”

Higher BMI, greater tobacco exposure, and more advanced pubertal development were also associated with more rapid aging. After adjustment for these covariates, however, the significant correlation between socioeconomic disadvantage and rapid aging remained, the investigators noted.

“Our results suggest that salivary DNA methylation measures of pace of aging may provide a surrogate or intermediate endpoint for understanding the health impacts of [childhood] interventions,” the investigators concluded. “Such applications may prove particularly useful for evaluating the effectiveness of health-promoting interventions in at-risk groups.”

Still, more work is needed to understand exactly how socioeconomic disadvantage is associated with accelerated aging.

“Ultimately, not only longitudinal repeated-measures studies but also natural experiment studies and randomized controlled trials of social programs are needed to establish causal effects of social disadvantage on DunedinPoAm-measured pace of aging and to establish DunedinPoAm as a mediator of the process through which childhood disadvantage leads to aging-related health conditions,” the investigators wrote.

In his editorial, Dr. Notterman emphasized this point.

“[I]t is worth remembering that associations with either methylation age or pace of aging and health or longevity may represent the effect of an exposure on both the measure and the outcome of interest rather than a causal pathway that runs from the exposure (low socioeconomic status, adversity) to health outcome (i.e., cancer, vascular disease),” he wrote.

Paul Chung, MD, professor and chair of health systems science at Kaiser Permanente Bernard J. Tyson School of Medicine, Pasadena, Calif., and adjunct professor at the University of California, Los Angeles, called the findings “preliminary,” but noted that confirmation through further research could “fill in some really important gaps.

“Right now, to some degree, we’re at a little bit of an impasse,” Dr. Chung said.

Adverse childhood experiences are “associated very strongly” with mental and physical health issues, Dr. Chung said, “but we don’t know exactly why, and because of that, it’s really hard to come up with social policy solutions that aren’t anything but extremely sort of blunt-ended. We just say, ‘Well, I guess you gotta fix everything.’ And it’s a hard place to be, I think, in the field.”

Although the present study doesn’t resolve this issue, Dr. Chung suggested that the findings “really open the door to a lot of really exciting research that could have a lot of impacts on practice and policy.”

“Sometimes the only way to get people to pay attention enough to generate the level of excitement that would allow you to even do these sorts of studies ... is to generate some initial exploratory data that makes people perk up their ears, and makes people go, ‘Hey, wow, maybe we should be looking into this.’ ”

The study by Dr. Raffington and colleagues was funded by the National Institutes of Health and the Jacobs Foundation, with additional support from the German Research Foundation, Russell Sage Foundation Biology and Social Science Grant, the Canadian Institute for Advanced Research Child and Brain Development Network, and others. The study by Dr. Lieshout and colleagues was supported by Canadian Institutes of Health Research. Dr. Factor-Litvak and Dr. Notterman reported funding from the National Institutes of Health. All of the investigators and interviewees reported no conflicts of interest.

 

Adversity in early life – whether preterm birth or socioeconomic disadvantage in childhood – accelerates aging, according to two recent studies, but underlying mechanisms remain unclear, and methods of investigation continue to evolve.

While one study used an established epigenetic clock to measure biological age among adults with extremely low birth weight, the other showcased a relatively new tool to measure pace of biological aging in disadvantaged children, suggesting that the metric may one day serve as a real-time measure of interventional efficacy.

These findings build upon previous studies that have demonstrated a correlation between biological age, also known as methylation age, and an increased risk of health problems later in life, according to Daniel A. Notterman, MD, professor of molecular biology at Princeton (N.J.) University.

“Finding that a person’s methylation age is greater than their chronological age has been taken as evidence of increased ‘biological age’ and perhaps a tendency to greater future morbidity,” Dr. Notterman wrote in a Pediatrics editorial. “Indeed, methylation age is advanced in association with a number of childhood and midlife adversities as well as morbidities such as atherosclerosis, cancer, and obesity.”
 

Extremely low birth weight associated with faster aging in men

For some individuals, accelerated biological aging begins at birth, or even in utero, according to Ryan J. Van Lieshout, MD, PhD, Canada Research Chair in the Perinatal Programming of Mental Disorders and the Albert Einstein/Irving Zucker Chair in Neuroscience at McMaster University, Hamilton, Ont., and colleagues.

The investigators conducted a study involving 45 extremely low birth weight (ELBW) survivors and 49 individuals born at normal birth weight. All participants were drawn from a longitudinal study conducted between 1977 and 1982 that assessed advances in neonatal intensive care. Controls were recruited at 8 years of age and matched with ELBW survivors based on family socioeconomic status, sex, and age. Follow-up continued through adulthood, allowing for the present trial to compare data from ages 8, 30, and 35.

Using samples of buccal epithelial cells, the investigators measured biological age with the Horvath epigenetic clock, the most commonly used tool of its kind, which measures cytosine-5 methylation at 353 cytosine-phosphate-guanine sites. Results were adjusted for a variety of covariates, such as smoking status, body mass index, number of chronic health conditions, and others.

Between groups, ELBW survivors trended toward older biological age, compared with adults born at normal birth weight (29.0 vs. 27.9 years), a difference that was not statistically significant. Further analysis, however, showed a significant sex-based difference between groups: Male survivors of ELBW, in adulthood, were almost 5 years biologically older than men born at normal birth weight (31.4 vs. 26.9 years; P = .01).

“[W]e provide preliminary evidence of a new link between ELBW and accelerated biological aging among men,” the investigators concluded.

In an accompanying editorial, Pam Factor-Litvak, PhD, vice chair of epidemiology at Columbia University, New York, wrote, “The findings are intriguing and open many questions for further study.”

Dr. Factor-Litvak noted that it remains unclear whether differences in biological aging were present at birth.

“[D]ifferences would provide evidence that accelerated aging begins during the in utero period, perhaps because of maternal undernutrition, stress, or another exposure,” Dr. Factor-Litvak wrote. “[R]eductions in chronic stress levels, which may begin for neonates with ELBW in utero and in the first hours of life, may provide an opportunity for interventions,” she added.

According to Calvin J. Hobel, MD, professor of pediatrics at Cedars-Sinai and professor of obstetrics and gynecology at University of California, Los Angeles, who has been studying preterm birth for more than 40 years, interventions may need to begin even earlier.

“The only way to prevent preterm birth is to do it before women get pregnant,” Dr. Hobel said in an interview. “The reason for preterm birth and poor fetal growth is the fact that the mother has early cardiovascular disease – unrecognized.”

Compared with women who give birth to full-term infants, women who give birth to preterm infants typically have increased blood pressure, Dr. Hobel said. Although these elevations in blood pressure are generally asymptomatic and not high enough to be classified as hypertensive, they impact umbilical artery vascular resistance starting at 28 weeks of gestation.

“In utero, [preterm infants] are programmed for increased vascular resistance and increased risk of cardiovascular disease,” Dr. Hobel said.

Regarding the effects of ELBW in men versus women, Dr. Hobel suggested that dissimilar neuroendocrine systems between sexes may protect females from adverse outcomes, although exact mechanisms remain elusive.
 

 

Measuring the impact of socioeconomic status on biological aging, now in real-time

A second study, by Laurel Raffington, PhD, of the University of Texas at Austin, and colleagues, evaluated the relationship between socioeconomic disadvantage in childhood and pace of biological aging.

To do so, they used the DunedinPoAm DNA methylation algorithm, a relatively new tool that was developed by analyzing changes in organ system integrity over time among adults with the same chronological age.

“Whereas epigenetic clocks quantify the amount of aging that has already occurred up to the time of measurement, DunedinPoAm quantifies how fast an individual is aging,” Dr. Raffington and colleagues wrote. “In other words, whereas epigenetic clocks tell you what time it is, pace-of-aging measures tell you how fast the clock is ticking.”

The investigators measured pace of aging in 600 children and adolescents (8-18 years of age) from the Texas Twin Project, “an ongoing longitudinal study that includes the collection of salivary samples.” The final dataset included 457 participants who identified as White, 77 who identified as Latinx, and 61 who identified as both White and Latinx.

The investigators evaluated pace of aging compared with family-level and neighborhood-level socioeconomic status, and tested for confounding by tobacco exposure, BMI, and pubertal development.

This analysis revealed that children experiencing socioeconomic disadvantage were aging more quickly than their peers, in terms of both family-level and neighborhood-level inequity (both levels, r = 0.18; P = .001).

Children who identified as Latinx aged faster than did those who identified as White only or White and Latinx, “consistent with higher levels of disadvantage in this group,” the investigators wrote. “Thus, our findings are consistent with observations that racial and/or ethnic socioeconomic disparities are an important contributor to racial and/or ethnic disparities in health.”

Higher BMI, greater tobacco exposure, and more advanced pubertal development were also associated with more rapid aging. After adjustment for these covariates, however, the significant correlation between socioeconomic disadvantage and rapid aging remained, the investigators noted.

“Our results suggest that salivary DNA methylation measures of pace of aging may provide a surrogate or intermediate endpoint for understanding the health impacts of [childhood] interventions,” the investigators concluded. “Such applications may prove particularly useful for evaluating the effectiveness of health-promoting interventions in at-risk groups.”

Still, more work is needed to understand exactly how socioeconomic disadvantage is associated with accelerated aging.

“Ultimately, not only longitudinal repeated-measures studies but also natural experiment studies and randomized controlled trials of social programs are needed to establish causal effects of social disadvantage on DunedinPoAm-measured pace of aging and to establish DunedinPoAm as a mediator of the process through which childhood disadvantage leads to aging-related health conditions,” the investigators wrote.

In his editorial, Dr. Notterman emphasized this point.

“[I]t is worth remembering that associations with either methylation age or pace of aging and health or longevity may represent the effect of an exposure on both the measure and the outcome of interest rather than a causal pathway that runs from the exposure (low socioeconomic status, adversity) to health outcome (i.e., cancer, vascular disease),” he wrote.

Paul Chung, MD, professor and chair of health systems science at Kaiser Permanente Bernard J. Tyson School of Medicine, Pasadena, Calif., and adjunct professor at the University of California, Los Angeles, called the findings “preliminary,” but noted that confirmation through further research could “fill in some really important gaps.

“Right now, to some degree, we’re at a little bit of an impasse,” Dr. Chung said.

Adverse childhood experiences are “associated very strongly” with mental and physical health issues, Dr. Chung said, “but we don’t know exactly why, and because of that, it’s really hard to come up with social policy solutions that aren’t anything but extremely sort of blunt-ended. We just say, ‘Well, I guess you gotta fix everything.’ And it’s a hard place to be, I think, in the field.”

Although the present study doesn’t resolve this issue, Dr. Chung suggested that the findings “really open the door to a lot of really exciting research that could have a lot of impacts on practice and policy.”

“Sometimes the only way to get people to pay attention enough to generate the level of excitement that would allow you to even do these sorts of studies ... is to generate some initial exploratory data that makes people perk up their ears, and makes people go, ‘Hey, wow, maybe we should be looking into this.’ ”

The study by Dr. Raffington and colleagues was funded by the National Institutes of Health and the Jacobs Foundation, with additional support from the German Research Foundation, Russell Sage Foundation Biology and Social Science Grant, the Canadian Institute for Advanced Research Child and Brain Development Network, and others. The study by Dr. Lieshout and colleagues was supported by Canadian Institutes of Health Research. Dr. Factor-Litvak and Dr. Notterman reported funding from the National Institutes of Health. All of the investigators and interviewees reported no conflicts of interest.