Despite the introduction of new antidepressants, major depressive disorder (MDD) remains challenging to treat. Antidepressant effectiveness trials conducted suggest depression remission rates of only 15%-35%. Therefore, new antidepressants with mechanisms that move beyond norepinephrine and serotonin targets are greatly needed. Importantly, comorbid symptoms including anxiety, cognitive complaints and somatic symptoms often co-occur with depression and further impact functioning and quality of life.

The lifetime prevalence of MDD in women at \> 20%, is approximately twice of that of men, with increased risk during the menopausal transition (perimenopause and early postmenopause). Hot flashes and other menopausal symptoms, such as cognitive symptoms and sleep dysregulation, affect up to 80% of women after perimenopause onset. Two large NIH-funded prospective epidemiological studies demonstrated an increased risk of onset of MDD during perimenopause (mMDD), with hormonal variability serving as a biomarker of risk of MDD. Short-term studies have demonstrated an augmentation benefit of estrogen and serotonin reuptake inhibitors can be used to target both mMDD and hot flashes. However, limited data from controlled trials suggest modest benefit for mMDD with standard antidepressants. Furthermore, due to safety concerns, many women prefer options other than estrogen replacement. Therefore, new and more effective treatments are needed for mMDD. Despite the fact that midlife women are the most frequent consumers of complementary and alternative therapies, trials of these approaches for mMDD are lacking. Pregnenolone is a naturally occurring neurosteroid made from cholesterol in the adrenal glands and brain, sold as an over-the-counter supplement, and the use of which at this time is common, unregulated and unstudied in women around the menopausal transition. Pregnenolone is a precursor of hormones known to fluctuate during the menopausal transition, and may decrease this hormonal variability known to increase the risk of MDD.

Preclinical research suggests that pregnenolone has antidepressant and neuroprotective effects, and improves cognition. Lower cerebrospinal fluid levels of pregnenolone are reported in people with bipolar disorder (BPD) or major depressive disorder (MDD) than controls. The investigators conducted two pilot studies of pregnenolone in depressed patients. The first study included patients with bipolar as well as unipolar depression (i.e. MDD). Pregnenolone (100 mg/d) was superior to placebo in improving depressive symptom severity. The second study found that 500 mg/d of pregnenolone was superior to placebo for bipolar depression. Baseline anxiety, fatigue, anhedonia and physical symptoms predicted a favorable depressive symptom response to pregnenolone compared to placebo. Improvement in cognition (e.g. declarative and working memory) was also observed in women given pregnenolone. Additionally, in women, changes in depressive symptoms showed strong inverse correlations with changes in pregnenolone (r=-0.83), and other neurosteroid levels. Furthermore, in both studies women responded better to pregnenolone relative to placebo for depression than men. Therefore, pregnenolone appears to have sex-specific antidepressant effects, or at least demonstrates a substantial sex difference in response. Women over age 40 showed a more robust response than younger women. Pregnenolone was very well tolerated in both studies. Based on these data, a larger, longer and more definitive trial of pregnenolone is now proposed. Unlike the prior pilot studies, this trial will be larger and focus on unipolar rather than bipolar depression, and will be limited to women with mMDD.

Given the widespread availability of pregnenolone, as well as promising preclinical and clinical data, and the extensive use of integrative treatments among midlife women, the investigators propose to examine its efficacy as an antidepressant in mMDD. Pregnenolone has the potential to provide women with an efficacious and appealing treatment option. To achieve this objective, a randomized, placebo-controlled trial of pregnenolone is proposed in 144 women with mMDD. A novel clinical trial design that enhances power to detect between-group differences and that allows for a longer observation period (16 weeks) will be used. Depressive symptoms, anxiety, quality of life, cognition and vasomotor symptoms (e.g. hot flashes) will be assessed. Blood levels of pregnenolone, and other neurosteroids (e.g. allopregnanolone, progesterone) will be obtained, and safety and tolerability data collected. A multiple PI team with extensive experience in mood disorders clinical trials, women's mental health and neurosteroids will conduct the study.