Administration of dehydroepiandrosterone (DHEA) enhances visual-spatial performance in postmenopausal women

Effect of dehydroepiandrosterone therapy on cognitive performance among postmenopausal women: a systematic review of randomized clinical trial data

IMPORTANCE

Whether dehydroepiandrosterone (DHEA) supplementation improves cognitive performance in older women is uncertain. Nonetheless, DHEA supplements are readily available over the counter in several countries and are potentially being used to prevent cognitive decline and dementia.

OBJECTIVE

This systematic review was conducted to evaluate the effect of exogenous DHEA on cognitive performance in postmenopausal women.

EVIDENCE REVIEW

Ovid MEDLINE, EMBASE, PsycINFO, Web of Science Core Collection, and the Cochrane Central Register of Controlled Trials databases were searched for studies of postmenopausal women until November 30, 2022. Eligible studies were required to be randomized clinical trials, be at least single blind, have a placebo or comparator arm and published in English. Risk of bias of the included studies was assessed by the revised Cochrane risk-of-bias tool.

FINDINGS

Of the 15 articles retrieved for full-text review, four met the inclusion criteria. In all studies DHEA was administered as a 50-mg oral daily dose and all were double blind with an identical placebo. Three were placebo-controlled, crossover studies and one was a parallel-group clinical trial. The only positive outcome was limited to a 4-wk cross-over study in which DHEA statistically significantly enhanced five of six tests of visual-spatial performance compared with placebo in 24 cognitively normal postmenopausal women. Improvement in cognitive performance with DHEA treatment over placebo group was not seen in any other study. Heterogeneity of design and use of multiple measures of cognitive performance was a barrier to meta-analysis and between study comparisons. The studies were limited by high risk of bias in multiple domains.

CONCLUSION AND RELEVANCE

Overall, this systematic review does not support a beneficial effect of DHEA therapy on cognitive performance in postmenopausal women.

Review of the effects of polycystic ovary syndrome on Cognition: Looking beyond the androgen hypothesis

Polycystic-ovary syndrome (PCOS) is the most common endocrine disorder affecting women of reproductive age, and many features associated with PCOS - such as elevated androgens, insulin resistance and inflammation - are known to affect cognition. However, effects of PCOS on cognition are not well-understood. Here we review the current literature on PCOS and cognition, note the extent of PCOS symptomatology studied in relation to cognitive outcomes, and identify key research gaps and common methodological concerns. Findings indicate a pattern of worse performance across cognitive domains and brain measures in women with PCOS relative to non-PCOS controls, as well as a lack of evidence for the common assumption that women with PCOS will have higher performance on tasks with a demonstrated male-advantage due to high testosterone levels. We suggest strategies for moving beyond the focus on elevated androgens, in favor of research practices that account for the nuances and heterogeneity of PCOS symptoms.

Androgens Enhance Recognition Memory and Dendritic Spine Density in the Hippocampus and Prefrontal Cortex of Ovariectomized Female Rats

Estrogen replacement has been repeatedly shown to enhance memory and increase dendritic spine density in the hippocampus and prefrontal cortex of ovariectomized (OVX) female rats. Given the potential deleterious effects of chronic estrogen administration, the present study assessed cognitive function using recognition memory tasks and measured dendritic spine density in the CA1 region of the hippocampus and medial prefrontal cortex after subchronic androgen replacement to adult OVX female rats. All androgens enhanced recognition memory in OVX rats, but object placement (OP) and object recognition (OR) results differed. Only testosterone enhanced OR. Testosterone had no effect on OP while dehydroepiandrosterone (DHEA), dihydrotestosterone (DHT) and androstenedione (AD) enhanced OP. Dendritic spine density was increased by both TP and DHEA in both brain areas (DHT and AD were not tested). Lastly, we used the aromatase inhibitor, letrozole, to discriminate between potential androgenic and estrogenic effects of androgens on behavior. Letrozole alone did not alter recognition memory in OVX rats and did not block the effects of either TP or DHEA on recognition memory suggesting that effects were mediated via androgenic mechanisms. The present results expand previous information on gonadal hormone actions and show that, in addition to estrogens, androgens also improve memory and increase spine density in brains of OVX female rats. While requiring further investigation, these observations provide a basis for therapeutic interventions in the treatment of menopausal, age or disease related memory loss.

Safety and efficacy of compounded bioidentical hormone therapy (cBHT) in perimenopausal and postmenopausal women: a systematic review and meta-analysis of randomized controlled trials

IMPORTANCE

More information is needed about the efficacy and safety of compounded bioidentical hormone therapy (cBHT) in the published literature. A thorough synthesis of existing data is not currently available.

OBJECTIVE

To provide a systematic review and meta-analysis of the existing evidence related to the safety and efficacy of commonly prescribed cBHT preparations in perimenopausal and postmenopausal women.

EVIDENCE REVIEW

PubMed, ClinicalTrials.gov, and The Cochrane Central Register of Controlled Trials were searched. Randomized controlled trials (RCTs) comparing cBHT with a placebo or FDA-approved products in perimenopausal or postmenopausal women were eligible. The risk of bias was assessed by the Cochrane risk of bias tool. The primary safety outcome was changes in lipid profile and glucose metabolism, and the primary efficacy outcome was the change of vaginal atrophy symptoms. The secondary outcomes included the change of endometrial thickness, risk of adverse events, vasomotor symptoms, change of serum hormone levels, and change of bone mineral density.

FINDINGS

A total of 29 RCTs reported in 40 articles containing 1,808 perimenopausal and postmenopausal women were included. Two risk factors of cardiovascular disease, lipid profile, and glucose metabolism, were evaluated with cBHT. The results showed that compounded androgen was not associated with change of lipid profile or glucose metabolism. There was no change in endometrial thickness or serious adverse events. There were more androgenic side effects with compounded dehydroepiandrosterone compared with placebo as expected. Other safety measures including clinical cardiovascular events, endometrial biopsy, and risk of breast cancer were not studied. cBHT in the form of compounded vaginal androgen was found to significantly improve vaginal atrophy symptoms (SMD -0.66 [95% CI, -1.28 to -0.04]; I2 = 86.70%). This finding was supported by the association between compounded vaginal androgen and improved female sexual function scores. The changes of serum hormone levels were also evaluated. Despite the variations in absorption from different types of compounded hormones, routes, and strengths, the trends were consistent with published data from FDA-approved products.

CONCLUSIONS AND RELEVANCE

This review found that cBHT used in primarily short-term RCTs is not associated with adverse changes in lipid profile or glucose metabolism. cBHT in the form of vaginal androgens appears beneficial for vaginal atrophy symptoms. There are insufficient RCTs of cBHT to assess clinical risk of breast cancer, endometrial cancer, or cardiovascular disease. Long-term studies with clinical endpoints are needed.

Impact of adrenal hormones, reproductive aging, and major depression on memory circuitry decline in early midlife

Dehydroepiandrosterone-sulfate (DHEAS) is an adrenal androgen that is, in part, aromatized to estradiol. It continues to be produced after menopause and provides estrogenicity after depletion of ovarian hormones. Estradiol depletion contributes to memory circuitry changes over menopause, including changes in hippocampal (HIPP) and dorsolateral- and ventrolateral-prefrontal cortex (DLPFC; VLPFC) function. Further, major depressive disorder (MDD) patients have, in general, lower levels of estradiol and lower DHEAS than healthy controls, thus potentially a higher risk of adverse menopausal outcomes. We investigated whether higher DHEAS levels after menopause is associated with better memory circuitry function, especially in women with MDD. 212 adults (ages 45-55, 50% women) underwent clinical and fMRI testing. Participants performed a working memory (WM) N-back task and an episodic memory verbal encoding (VE) task during fMRI scanning. DHEAS levels were significantly associated with memory circuitry function, specifically in MDD postmenopausal women. On the WM task, lower DHEAS levels were associated with increased HIPP activity. On the VE task, lower DHEAS levels were associated with decreased activity in the HIPP and VLPFC. In contrast, there was no association between DHEAS levels and memory circuitry function in MDD pre/perimenopausal women, men, and non-MDD participants regardless of sex and reproductive status. In fact, MDD postmenopausal women with higher levels of DHEAS were similar to MDD pre/perimenopausal women and men. Thus, memory circuitry deficits associated with MDD and a lower ability of the adrenal gland to produce DHEAS after menopause may contribute to a lower ability to maintain intact memory function with age.

Sex-specific contribution of DHEA-cortisol ratio to prefrontal-hippocampal structural development, cognitive abilities and personality traits

Although dehydroepiandrosterone (DHEA) may exert neuroprotective effects in the developing brain, prolonged or excessive elevations in cortisol may exert neurotoxic effects. The ratio between DHEA and cortisol (DC ratio) has been linked to internalising and externalising disorders, as well as cognitive performance, supporting the clinical relevance of this hormonal ratio during development. However, the brain mechanisms by which these effects may be mediated have not yet been identified. Furthermore, although there is evidence that the effects of cortisol in the central nervous system may be sexually dimorphic in humans, the opposite is true for DHEA, with human studies showing no sex-specific associations in cortical thickness, cortico-amygdalar or cortico-hippocampal structural covariance. Therefore, it remains unclear whether sex moderates the developmental associations between DC ratio, brain structure, cognition and behaviour. In the present study, we examined the associations between DC ratio, structural covariance of the hippocampus with whole-brain cortical thickness, and measures of personality, behaviour and cognition in a longitudinal sample of typically developing children, adolescents and young adults aged 6-22 years (N = 225 participants [F = 128]; 355 scans [F = 208]), using mixed effects models that accounted for both within- and between-subject variances. We found sex-specific interactions between DC ratio and anterior cingulate cortex-hippocampal structural covariance, with higher DC ratios being associated with a more negative covariance between these structures in girls, and a more positive covariance in boys. Furthermore, the negative prefrontal-hippocampal structural covariance found in girls was associated with higher verbal memory and mathematical ability, whereas the positive covariance found in boys was associated with lower cooperativeness and reward dependence personality traits. These findings support the notion that the ratio between DHEA and cortisol levels may contribute, at least in part, to the development of sex differences in cognitive abilities, as well as risk for internalising/externalising disorders, via an alteration in prefrontal-hippocampal structure during the transition from childhood to adulthood.

Effects of short-term DHEA intake on hormonal responses in young recreationally trained athletes: modulation by gender

BACKGROUND

Dehydroepiandrosterone (DHEA) figures on the World Anti-Doping Agency list of prohibited substances in sport because it is assumed that athletes expect a significant increase in testosterone through DHEA administration. The literature on the hormonal effects of DHEA intake nevertheless appears to be very scant in healthy young subjects, especially women.

PURPOSE

We examined the effects of DHEA on adrenal and gonadal hormones, IGF1 and free T3 in healthy young male and female recreationally trained volunteers.

METHODS

The study followed a double-blind, randomized-order crossover design. Lean healthy young men (n = 10) and women (n = 11), with all women using oral contraceptives, were treated daily with 100 mg of DHEA and placebo for 4 weeks. DHEA, DHEA-sulfate (DHEA-S), androstenedione, total testosterone (Tes), dihydrotestosterone (DHT), SHBG, estrone, cortisol, IGF1, and free T3 were measured before, in the middle and at the end of each treatment, as were blood glucose, liver transaminases and lipid status.

RESULTS

We observed a significant increase in DHEA, DHEA-S, androstenedione, Tes, DHT, and estrone in both men and women in the middle and at the end of DHEA treatment, but the increase in Tes was more marked in women (p < 0.001) than men (p < 0.05). No changes were found in the other parameters, irrespective of gender.

CONCLUSION

In young athletes, DHEA administration induces significant blood hormonal changes, some modulated by gender, which can be used as biomarkers of doping.

Use of Galvanic Skin Responses, Salivary Biomarkers, and Self-reports to Assess Undergraduate Student Performance During a Laboratory Exam Activity

Typically, self-reports are used in educational research to assess student response and performance to a classroom activity. Yet, addition of biological and physiological measures such as salivary biomarkers and galvanic skin responses are rarely included, limiting the wealth of information that can be obtained to better understand student performance. A laboratory protocol to study undergraduate students' responses to classroom events (e.g., exams) is presented. Participants were asked to complete a representative exam for their degree. Before and after the laboratory exam session, students completed an academic achievement emotions self-report and an interview that paralleled these questions when participants wore a galvanic skin sensor and salivary biomarkers were collected. Data collected from the three methods resulted in greater depth of information about students' performance when compared to the self-report. The work can expand educational research capabilities through more comprehensive methods for obtaining nearer to real-time student responses to an examination activity.

Oxytocin, testosterone, and human social cognition

I describe an integrative social-evolutionary model for the adaptive significance of the human oxytocinergic system. The model is based on a role for this hormone in the generation and maintenance of social familiarity and affiliation across five homologous, functionally similar, and sequentially co-opted contexts: mothers with offspring, female and male mates, kin groups, individuals with reciprocity partners, and individuals within cooperating and competing social groups defined by culture. In each situation, oxytocin motivates, mediates and rewards the cognitive and behavioural processes that underlie the formation and dynamics of a more or less stable social group, and promotes a relationship between two or more individuals. Such relationships may be positive (eliciting neurological reward, reducing anxiety and thus indicating fitness-enhancing effects), or negative (increasing anxiety and distress, and thus motivating attempts to alleviate a problematic, fitness-reducing social situation). I also present evidence that testosterone exhibits opposite effects from oxytocin on diverse aspects of cognition and behaviour, most generally by favouring self-oriented, asocial and antisocial behaviours. I apply this model for effects of oxytocin and testosterone to understanding human psychological disorders centrally involving social behaviour. Reduced oxytocin and higher testosterone levels have been associated with under-developed social cognition, especially in autism. By contrast, some combination of oxytocin increased above normal levels, and lower testosterone, has been reported in a notable number of studies of schizophrenia, bipolar disorder and depression, and, in some cases, higher oxytocin involves maladaptively 'hyper-developed' social cognition in these conditions. This pattern of findings suggests that human social cognition and behaviour are structured, in part, by joint and opposing effects of oxytocin and testosterone, and that extremes of such joint effects partially mediate risks and phenotypes of autism and psychotic-affective conditions. These considerations have direct implications for the development of therapies for alleviating disorders of social cognition, and for understanding how such disorders are associated with the evolution of human cognitive-affective architecture.

Dehydroepiandrosterone for women in the peri- or postmenopausal phase

BACKGROUND

During menopause a decreasing ovarian follicular response generally causes a fluctuation and eventual decrease in estrogen levels. This can lead to the development of various perimenopausal and postmenopausal symptoms (for example hot flushes, night sweats, vaginal dryness). Dehydroepiandrosterone (DHEA) is one of the main precursors of androgens, which in turn are converted to testosterone and estrogens. It is possible that the administration of DHEA may increase estrogen and testosterone levels in peri- and postmenopausal women to alleviate their symptoms and improve general wellbeing and sexual function (for example libido, dyspareunia, satisfaction). Treatment with DHEA is controversial as there is uncertainty about its effectiveness and safety. This review should clearly outline the evidence for DHEA in the treatment of menopausal symptoms and evaluate its effectiveness and safety by combining the results of randomised controlled trials.

OBJECTIVES

To assess the effectiveness and safety of administering DHEA to women with menopausal symptoms in the peri- or postmenopausal phase.

SEARCH METHODS

The databases that we searched (3 June 2014) with no language restrictions applied were the Cochrane Menstrual Disorders and Subfertility Group Specialised Register, Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, PsycINFO, CINAHL and LILACS. We also searched conference abstracts and citation lists in the ISI Web of Knowledge. Ongoing trials were searched in the trials registers. Reference lists of retrieved articles were checked.

SELECTION CRITERIA

We included randomised controlled trials comparing any dose and form of DHEA by any route of administration versus any other active intervention, placebo or no treatment for a minimal treatment duration of seven days in peri- and postmenopausal women.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data after assessing eligibility for inclusion and quality of studies. Authors were contacted for additional information.

MAIN RESULTS

Twenty-eight trials with 1273 menopausal women were included in this review. Data could be extracted from 16 trials to conduct the meta-analysis. The overall quality of the studies was moderate to low with the majority of studies that were included in the meta-analysis having reasonable methodology. Compared to placebo, DHEA did not improve quality of life (standardised mean difference (SMD) 0.16, 95% confidence interval (CI) -0.03 to 0.34, P = 0.10, 8 studies, 287 women (132 from parallel and 155 from crossover trials), I² = 0%, moderate quality evidence; one trial of the nine that reported on this outcome was removed in a sensitivity analysis as it was judged to be at high risk of bias). DHEA was found to be associated with androgenic side effects (mainly acne) (odds ratio (OR) 3.77, 95% CI 1.36 to 10.4, P = 0.01, 5 studies, 376 women, I² = 10%, moderate quality evidence) when compared to placebo. No associations were found with other adverse effects. It was unclear whether DHEA affected menopausal symptoms as the results from the trials were inconsistent and could not easily be pooled to provide an overall effect due to different types of measurement (for example continuous, dichotomous, change and end scores). DHEA was found to improve sexual function (SMD 0.31, 95% CI 0.07 to 0.55, P = 0.01, 5 studies, 261 women (239 women from parallel trials and 22 women from crossover trials), I² = 0%; one trial judged to be at high risk of bias was removed during sensitivity analysis) compared to placebo.There was no difference in the acne associated with DHEA when comparing studies that used oral DHEA (OR 2.16, 95% CI 0.47 to 9.96, P = 0.90, 3 studies, 136 women, I² = 5%, very low quality evidence) to one study that used skin application of DHEA (OR 2.74, 95% CI 0.10 to 74.87, P = 0.90, 1 study, 22 women, very low quality evidence). The effects did not differ for sexual function when studies using oral DHEA (SMD 0.11, 95% CI -0.13 to 0.35, P = 0.36, 5 studies, 340 women, I² = 0) were compared to a study using intravaginal DHEA (SMD 0.42, 95% CI 0.03 to 0.81, 1 study, 218 women). Test for subgroup differences: Chi² = 1.77, df = 1 (P = 0.18), I² = 43.4%. Insufficient data were available to assess quality of life and menopausal symptoms for this comparison.There were insufficient data available to compare the effects of DHEA to hormone therapy (HT) for quality of life, menopausal symptoms, and adverse effects. No large differences in treatment effects were found for sexual function when comparing DHEA to HT (mean difference (MD) 1.26, 95% CI -0.21 to 2.73, P = 0.09, 2 studies, 41 women, I² = 0%).

AUTHORS' CONCLUSIONS

There is no evidence that DHEA improves quality of life but there is some evidence that it is associated with androgenic side effects. There is uncertainty whether DHEA decreases menopausal symptoms, but DHEA may slightly improve sexual function compared with placebo.

DHEA and cognitive function in the elderly

The adrenal prohormone dehydroepiandrosterone (DHEA) and its sulphate conjugate (DHEAS) steadily decrease with age by 10% per decade reaching a nadir after the age of 80. Both DHEA and DHEAS (DHEA/S) exert many biological activities in different tissues and organs. In particular, DHEA and DHEAS are produced de novo in the brain, hence their classification as neurosteroids. In humans, the brain-to-plasma ratios for DHEA and DHEAS are 4-6.5 and 8.5, respectively, indicating a specific neuroendocrine role for these hormones. DHEA/S stimulates neurite growth, neurogenesis and neuronal survival, apoptosis, catecholamine synthesis and secretion. Together with antioxidant, anti-inflammatory and anti-glucocorticoid properties, it has been hypothesized a neuroprotective effect for DHEA/S. We conducted an accurate research of the literature using PubMed. In the period of time between 1994 and 2013, we selected the observational human studies testing the relationship between DHEA/S and cognitive function in both sexes. The studies are presented according to the cross-sectional and longitudinal design and to the positive or neutral effects on different domains of cognitive function. We also analysed the Clinical Trials, available in the literature, having cognitive domains as the main or secondary outcome. Although the cross-sectional evidence of a positive association between DHEA/S and cognitive function, longitudinal studies and RCTs using DHEA oral treatment (50mg/day) in normal or demented adult-older subjects, have produced conflicting and inconsistent results. In summary, the current data do not provide clear evidence for the usefulness of DHEA treatment to improve cognitive function in adult-older subjects. This article is part of a Special Issue entitled 'Essential role of DHEA'.

The relationship between dehydroepiandrosterone (DHEA), working memory and distraction--a behavioral and electrophysiological approach

Dehydroepiandrosterone (DHEA) and dehydroepiandrosterone-sulphate (DHEAS) have been reported to have memory enhancement effects in humans. A neuro-stimulatory action and an anti-cortisol mechanism of action may contribute to that relation. In order to study DHEA, DHEAS and cortisol relations to working memory and distraction, we recorded the electroencephalogram of 23 young women performing a discrimination (no working memory load) or 1-back (working memory load) task in an audio-visual oddball paradigm. We measured salivary DHEA, DHEAS and cortisol both before each task and at 30 and 60 min. Under working memory load, a higher baseline cortisol/DHEA ratio was related to higher distraction as indexed by an enhanced novelty P3. This suggests that cortisol may lead to increased distraction whereas DHEA may hinder distraction by leading to less processing of the distractor. An increased DHEA production with consecutive cognitive tasks was found and higher DHEA responses attributed to working memory load were related to enhanced working memory processing as indexed by an enhanced visual P300. Overall, the results suggest that in women DHEA may oppose cortisol effects reducing distraction and that a higher DHEA response may enhance working memory at the electrophysiological level.

Sex hormones and mental rotation: an intensive longitudinal investigation

The present study used an intensive longitudinal design to examine whether mental rotation performance varies according to a monthly cycle in both males and females and whether these variations are related to variations in progesterone, estradiol, and testosterone levels. We collected reaction time and accuracy data for 10 males and seven females each workday over eight weeks using 136 pairs of mental rotation stimuli/day, and measured sexual hormones concentrations in the saliva twice a week. A mixed linear model statistical analysis revealed that all females and seven males showed significant cycle effects in mental rotation performance. The female cycle showed an amplitude that was twice as large compared with the amplitude found in males. For males and females, estradiol and testosterone were significantly linearly and quadratically related to interindividual variation in performance at the beginning of the study (progesterone was linearly related to performance for females). The association between testosterone and performance differed across sexes: for males, it had an inverse U-shape, for females it was U-shaped. Towards the end of the study, none of the hormones were significantly related to performance anymore. Thus, the relationship between hormones and mental rotation performance disappeared with repeated testing. Only estradiol levels were significantly elevated at the lowest point of the cycle in mental rotation performance in females. In conclusion, in this intensive longitudinal study spanning two months, a monthly cycle in mental rotation performance was found among both males and females, with a larger cycle's amplitude for females.

Protective cardiovascular and renal actions of vitamin D and estrogen

Both basic science and clinical studies support the concept that vitamin D deficiency is involved in the pathogenesis of cardiovascular and renal diseases through its association with diabetes, obesity, and hypertension. Understanding the underlying mechanisms may provide a rationale for advocating adequate intake of vitamin D and calcium in all populations, thereby preventing many chronic diseases. This review explores the effect of vitamin D deficiency in the development of cardiovascular and renal diseases, and the role of vitamin D supplementation on cardiovascular outcomes. In addition, it highlights the importance of vitamin D intake for the prevention of adverse long-term health consequences, and in ways to facilitate the management of cardiovascular disease. This is particularly true for African American and postmenopausal women, who are at added risk for cardiovascular disease. We suggest that the negative cardiovascular effects of low vitamin D in postmenopausal women could be improved by a combined treatment of vitamin D and sex steroids acting through endothelium-dependent and/or -independent mechanisms, resulting in the generation of nitric oxide and calcitonin gene-related peptide (CGRP).

Administration of dehydroepiandrosterone (DHEA) increases serum levels of androgens and estrogens but does not enhance short-term memory in post-menopausal women

The current study examines the effect of administering dehydroepiandrosterone (DHEA) on short-term memory. This experiment used a double-blind placebo-controlled cross-over design to explore the effects of a four week regimen of 50 mg oral DHEA on performance on the digit span, verbal span, and modified Sternberg (Oberauer) tasks. The results demonstrate that the current regimen of drug administration significantly increases serum levels of DHEA, DHEAS, testosterone and estrone and substantially alters the patterns of correlations among the serum levels of these hormones. Despite this substantial change in the hormonal milieu, DHEA administration produced no beneficial effects on cognitive performance in the digit span, verbal span, or modified Sternberg paradigm tasks. Ancillary analyses of the relation between hormone levels and cognitive performance demonstrated a strong positive correlation between DHEA levels and performance on digit span forward/backward and verbal span forward in the placebo drug condition, but not in the DHEA condition. We interpret the juxtaposition of the null results of DHEA administration and the correlation of DHEA levels and performance in the placebo condition to indicate that the referenced correlations arise because a third variable (i.e., age) is associated with both performance and DHEA levels. Additional analyses supported this hypothesis.