Why does brain fog get worse in your 30s and 40s, and what can you do about it?

Brain fog in your 30s and 40s is not imagined and it is not a personal failing. It has a biology. As women move through the decade from 35 to 45, a convergence of factors, including shifting reproductive hormones, cellular energy changes, and often compounding sleep and stress demands, affects the brain's ability to function at the clarity level many women were used to. NAD+, a coenzyme essential to cellular energy production, declines naturally with age, and research suggests this decline may contribute to the fatigue, reduced mental clarity, and diminished cognitive resilience that many women begin to notice during this period. There is a real story here, and it deserves a real answer.

What is actually happening in the brain during this decade

Your brain consumes roughly 20% of your body's total energy despite making up only about 2% of your body weight. That makes it unusually dependent on efficient cellular energy production. NAD+ (nicotinamide adenine dinucleotide) is the coenzyme that sits at the center of that energy system: it is required for cellular ATP generation, DNA repair, and the signaling pathways that keep neurons functioning. When NAD+ levels decline, as they do naturally with age, the brain is one of the organs that feels it first.

Research using advanced measurement techniques has demonstrated that NAD+ levels in brain tissue decline measurably with age, according to the Alzheimer's Drug Discovery Foundation's Cognitive Vitality review. A published clinical trial using nicotinamide riboside (NR), an orally bioavailable NAD+ precursor, demonstrated that NR supplementation increases blood NAD+ levels in healthy middle-aged and older adults, with researchers suggesting further trials to assess the implications for blood pressure and other physiological markers.

The perimenopause layer

For women in their late 30s and 40s, the NAD+ decline story is complicated by the perimenopause transition. Estrogen plays a role in brain energy metabolism and supports mitochondrial function. As estrogen fluctuates and eventually declines, it can compound the effect of NAD+ depletion on cognitive function. This is why so many women describe their brain fog as qualitatively different from the mental fatigue they experienced in their 20s. It is not just tiredness. It is a change in the texture of thinking: slower word retrieval, shorter windows of sustained focus, memory that feels less automatic than it used to.

A clinical pilot study published in Maturitas found that nicotinamide riboside improved menopausal symptoms and skeletal muscle mitochondrial function in postmenopausal women, pointing to a direct connection between NAD+ precursor supplementation and the cellular energy systems affected during the hormonal transition. This research is preliminary and the field is active, but it supports NAD+ as a legitimate area of investigation for women in this life stage.

"I want to be able to move and move well and be healthy for a long time."

— Dominique Landry, Founder of Fit Enough

NAD+ supplementation: what Nicotinamide Riboside actually does

Pink Stork NAD+, a cellular energy supplement formulated for women, delivers 500 mg of Nicotinamide Riboside (NR) per capsule. NR is a bioavailable precursor to NAD+, meaning the body uses it as a building block to produce NAD+ in tissues throughout the body, including in the brain. A randomized, double-blind, placebo-controlled trial published in Nature Partner Journals Aging confirmed that chronic NR supplementation is well tolerated and effectively elevates NAD+ in healthy middle-aged and older adults.

Formulated without resveratrol, Pink Stork NAD+ is designed for optimal NR bioavailability. It is third-party tested in cGMP-certified laboratories, vegan, non-GMO, and gluten-free. NAD+ supports cellular energy production, cognitive function and mental clarity, and healthy aging.† Always consult your healthcare provider before starting any new supplement.

The creatine cognitive story that most women have not heard

Creatine is almost always framed as a gym supplement for muscle performance. That framing misses a significant part of the research picture, particularly for women. The brain stores creatine and uses the phosphocreatine-ATP energy system just as muscles do. When creatine stores are low, the brain has less buffer capacity during cognitively demanding periods.

A 2024 systematic review and meta-analysis of 16 randomized controlled trials on creatine and cognitive function, published in Frontiers in Nutrition, found that subgroup analyses revealed creatine supplementation was more beneficial in females than males for cognitive outcomes, particularly in the domains of memory and processing speed. Research also suggests that women naturally have 70 to 80% lower creatine stores than men, which means the floor women are starting from is lower and the relative benefit of supplementation may be greater.

Pink Stork Creatine Monohydrate, 5 grams per serving with no added fillers, is single-ingredient micronized creatine monohydrate, the form used in all of the cognitive research. Vegan, non-GMO, gluten-free, and third-party tested. It supports cellular energy production and cognitive function and mental clarity.† Consult your healthcare provider before starting any new supplement.

"Women's bodies and brains are doing extraordinary work across every decade. We built our products to support what is already happening, not to override it."

— Amy Suzanne Upchurch, Founder and CEO of Pink Stork

Three habits that the research actually supports for cognitive function after 35

Supplementation is one layer. The lifestyle foundations that support brain health in midlife are well-documented and worth naming directly.

Strength training has a documented positive effect on cognitive function. Resistance exercise increases brain-derived neurotrophic factor (BDNF), improves blood flow to the brain, and supports the same mitochondrial systems that NAD+ and creatine target. Even two sessions per week have shown meaningful effects in research on women.

Omega-3 DHA is the fatty acid most concentrated in the brain. Low DHA has been associated with poorer cognitive outcomes in aging populations, and supplementation has shown effects on memory-related outcomes in research. Pink Stork Cortisol Complex includes 100 mg of algae-sourced DHA, a plant-based, mercury-free form of this essential fatty acid, as part of its daily formula.

Sleep architecture, specifically the quality of your deep and REM sleep, is when the brain consolidates memory and clears metabolic waste. Women in perimenopause frequently experience disrupted sleep as a primary symptom, which compounds the cognitive effects of NAD+ and creatine decline. Addressing sleep quality directly, whether through magnesium glycinate, sleep hygiene, or a conversation with your provider about hormonal factors, is not optional for brain health during this decade.

How to think about the NAD+ and creatine combination

NAD+ and creatine address cognitive support from complementary angles. NAD+ targets the cellular energy production pathway that fuels neuronal function at a foundational level.† Creatine targets the phosphocreatine-ATP buffer system that supports the brain during active cognitive demand.† They are not redundant. Together with adequate DHA, sleep support, and strength training, they form a coherent evidence-based approach to cognitive support in the 35-plus decade.

For more detail on specific aspects of this topic, read our subtopic guides: Why do so many women experience brain fog during perimenopause?, What habits actually support cognitive function for women after 35?, What is NAD+ and why does it matter for women over 30?, and Can creatine support brain function in women?

Frequently asked questions about brain fog and cognitive support for women

Is brain fog a normal part of getting older for women?

Brain fog and cognitive changes in your 30s and 40s have a documented biological basis, including age-related declines in NAD+ and, for women in perimenopause, shifting estrogen levels that affect brain energy metabolism. These changes are real, but they are not inevitable in their severity. Nutrition, sleep, strength training, and targeted supplementation all have evidence for supporting cognitive function during this period.

What is NAD+ and why does it decline with age?

NAD+ is a coenzyme present in every cell that is essential for cellular energy production, DNA repair, and cellular signaling. NAD+ levels decline naturally with age in multiple tissues, including in the brain and in female reproductive organs. The exact mechanism involves a decrease in the enzymes responsible for NAD+ biosynthesis. Supplementing with NAD+ precursors like Nicotinamide Riboside (NR) has been shown in clinical trials to elevate NAD+ levels in blood and tissues in healthy adults.

Does creatine work for brain fog in women?

Research suggests that creatine supplementation supports memory and processing speed, with some evidence that the effect is stronger in females than in males. The brain uses creatine as an energy buffer, and women naturally have lower creatine stores than men, which may explain the relative benefit. The evidence base is growing but not yet definitive, and most cognitive effects were observed with consistent supplementation over several weeks.†

Is it safe to take NAD+ and creatine together?

Both NAD+ and creatine are well-tolerated in research at standard doses. They work through different mechanisms and are not known to interact. As with any supplement combination, consult your healthcare provider before starting, particularly if you have existing health conditions or take prescription medications.

How long does it take to notice benefits from NAD+ supplementation?

Most clinical studies on NR supplementation observe effects over weeks to months of consistent daily use. NAD+ is not a stimulant and does not produce an immediate noticeable effect. Benefits, when they occur, tend to build gradually and are often described as improved energy consistency and cognitive resilience rather than an acute change.†

Can perimenopause cause brain fog even if I am not having hot flashes?

Yes. Cognitive changes, including difficulty with word retrieval, sustained focus, and short-term memory, are among the symptoms that can emerge in perimenopause even without the classic vasomotor symptoms like hot flashes. These changes are related to shifts in brain energy metabolism as estrogen fluctuates, and they may be present for years before the menstrual cycle changes significantly. Speak with your healthcare provider if these symptoms are affecting your quality of life.

† These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease. Always consult your healthcare provider before starting any new supplement, especially during pregnancy, breastfeeding, or while managing a medical condition. Keep out of reach of children.