What does NAD+ do for your brain?
NAD+ is biologically crucial for your brain and declines with age, but whether supplementation via NMN or other means genuinely protects humans has not yet been convincingly demonstrated. Wait for the results of larger clinical studies before drawing firm conclusions.
NAD+ is present in all your cells, including your brain cells. It is indispensable for energy production, DNA repair, healthy mitochondria (the powerhouses of your cells), and the resilience of neurons under stress. Several NAD+-dependent enzymes also play a role in synaptic plasticity, the ability of your brain to strengthen or weaken connections. That is the foundation of learning and memory1.
As you age, your NAD+ levels decline, including in your brain. This is seen as a possible explanation for why older brains are more susceptible to decline and disease. It remains a hypothesis for now: the precise cause and effect in humans has not yet been firmly established2.
In Alzheimer's disease, the link with NAD+ has been studied most extensively, but almost everything comes from mouse studies. Mice with advanced Alzheimer's showed, after restoration of NAD+ metabolism, less accumulation of harmful proteins, less inflammation and oxidative damage, and a restored blood-brain barrier. Their cognition improved completely. Separate mouse studies show that NAD+ supplementation reduces neuroinflammation and senescence, the process by which damaged cells continue to release harmful substances3,4. Impressive, but whether this also works in humans is still unknown.
NAD+ supplements, such as NMN, are available as a supplement. In cell and mouse studies they raise NAD+ levels and inhibit age-related processes such as DNA damage. One mouse study showed that NMN counteracts leakage of the blood-brain barrier by restoring NAD+ levels in the brain's blood vessels5. Human studies to date are small or still ongoing. The same effect seen in mice has not yet been demonstrated2.
There is also a broader story: your body produces NAD+ via a pathway that starts with tryptophan, an amino acid from food. Some intermediates in that pathway protect brain cells, while others are actually toxic. Dysregulation of this pathway is associated in mouse studies with depression-like behaviour and cognitive problems. In humans there is a link with psychiatric conditions during inflammation6. It is therefore not only about how much NAD+ you produce, but also which intermediates are released along the way.
All claims are based on the supplied abstracts (PMID 31577933, 37619764, 41435831, 31893583, 37683629, 30980044). The human evidence is limited to association studies and small trials. Most mechanistic and intervention data come from mouse studies and cell research.
What does a vitamin D deficiency do to your brain?
A vitamin D deficiency is consistently linked to a higher risk of cognitive decline, dementia, and other brain conditions, but whether replenishing vitamin D actually prevents or slows these conditions has not been proven. Maintaining adequate vitamin D levels is therefore sensible for its broader health benefits, but supplementation should not be counted on as protection against brain disease.
Do ketone drinks do anything for your brain or performance?
For people with memory complaints the early signals are cautiously positive, but the studies are small and not conclusive. As a healthy athlete or average person, you have too little to go on to use ketone drinks with confidence.
What does air pollution do to your brain in the long term?
Long-term exposure to air pollution, and fine particulate matter in particular, is associated with an increased risk of dementia and faster memory decline. The associations have been demonstrated in multiple human studies, but a direct cause-and-effect relationship has not yet been conclusively proven.
What does alcohol do to your brain in the long term?
Long-term heavy drinking demonstrably damages the brain, in part irreversibly. Stopping helps, but after years of heavy use it should always be done under medical supervision.
What is NAD+ and what does it do in your body?
NAD+ is an indispensable molecule for energy, DNA repair and cell health, but the question of whether you should actively raise those levels for better health has not yet been answered for humans.
What is NAD+ and why does it decline as you age?
NAD+ is an indispensable energy carrier and guardian of your DNA, and your body produces less of it as you age. The mechanisms behind that decline are reasonably well understood, but what you can practically do about it is still very much under investigation.