What does NAD+ do for your brain?
NAD+ matters for your brain and declines with age. Whether topping it up via NMN (a substance your body converts into NAD+) or other means actually helps has not yet been convincingly demonstrated in people. Wait for the results of larger studies in people before drawing firm conclusions.
NAD+ is present in all your cells, including your brain cells. It is essential for energy production, DNA repair, healthy mitochondria (the power stations inside your cells), and the ability of neurons to withstand stress. Several enzymes that depend on NAD+ also play a role in synaptic plasticity, meaning your brain's ability to strengthen or weaken connections between cells. That is the foundation of learning and memory.
As you get older, your NAD+ levels fall, including in your brain. This is seen as a possible explanation for why ageing brains are more vulnerable to decline and disease. For now it remains a hypothesis: the precise cause and effect in people has not yet been firmly established.
In Alzheimer's disease, the link with NAD+ has been studied most extensively, but almost everything comes from studies in mice. Mice with advanced Alzheimer's showed less build-up of harmful proteins, less inflammation and cellular damage, and a restored blood-brain barrier after their NAD+ levels were brought back up. Their cognition improved completely. Separate studies in mice show that boosting NAD+ reduces brain inflammation and the accumulation of damaged cells that keep releasing harmful substances into their surroundings. Impressive, but whether this also applies to people is not yet known.
NAD+ supplements such as NMN are available to buy. Studies in cells and mice show that they raise NAD+ levels and slow down age-related processes such as DNA damage. One study in mice showed that NMN counteracts leakage of the blood-brain barrier by restoring NAD+ levels in the blood vessels of the brain. Studies in people have so far been small or are still ongoing. The same effect seen in mice has not yet been demonstrated in people.
There is also a broader picture: your body produces NAD+ through a process that starts with tryptophan, an amino acid found in food. Some of the intermediate substances produced along the way protect brain cells, while others are actually harmful. In studies in mice, disruption of this process is linked to depression-like behaviour and cognitive problems. In people, there is an association with psychiatric conditions during periods of inflammation. So it is not just about how much NAD+ you produce, but also which intermediate substances are released along the way.
All claims are based on the supplied abstracts. The evidence in people is limited to association studies and small trials. Most mechanistic and intervention data come from studies in mice and experiments with cells.
What does a vitamin D deficiency do to your brain?
A vitamin D deficiency is associated with a higher risk of cognitive decline and dementia, but whether correcting it with supplements actually protects your brain has not yet been proven. If you think you may be deficient, discuss it with your doctor.
Do ketone drinks do anything for your brain or performance?
For athletes, ketone drinks offer no advantage, and at altitude people actually perform slightly worse when using them. For people with memory problems, the early signs are cautiously positive, but the studies are too varied to base firm advice on.
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 maintenance, and its levels measurably decline with age. Whether that decline can be corrected with supplements, and what benefit that would bring, is a separate question.
What is NAD+ and why does it decline as you age?
NAD+ measurably declines with ageing, and supplements raise levels demonstrably in people. Whether that also makes you healthier has not yet been proven, and the safety of taking them for many years deserves attention.