NAD+ and Alzheimer's: What the Latest Research Actually Shows (2026)

In March 2026, Nature Aging published an expert review that could reshape how we think about NAD+ therapy — not just for general longevity, but specifically for the most feared age-related diseases: Alzheimer’s and Parkinson’s.¹

The paper, led by researchers at the University of Oslo (UiO) and Akershus University Hospital (Ahus), brings together more than 25 scientists spanning aging biology, metabolism, and clinical neurology. Their conclusion: NAD+ augmentation strategies hold genuine promise for neurodegenerative disease, but the field is drowning in premature commercialization and needs larger, longer clinical trials before claims can be confirmed.

This is the most authoritative synthesis of NAD+ neuroscience to date. Here’s what it says, what it means for patients, and how it connects to the treatments offered at longevity clinics today.

Why NAD+ Matters for the Brain

NAD+ (nicotinamide adenine dinucleotide) is a coenzyme present in every cell. It functions as a “fuel regulator” — central to energy production (ATP synthesis), DNA repair (activating PARP enzymes), and cellular stress responses (activating sirtuins).²

The brain is uniquely dependent on NAD+. Neurons are among the most metabolically demanding cells in the body, consuming approximately 20% of the body’s total energy despite representing only 2% of its mass. They cannot store energy. They rely on continuous mitochondrial ATP production, which depends on NAD+ availability.

Here’s the problem: NAD+ levels decline with age, and the decline is particularly severe in the brain. Post-mortem studies have shown significantly reduced NAD+ concentrations in brain tissue from Alzheimer’s and Parkinson’s patients compared to age-matched controls.³

The biological chain is direct:

Aging → NAD+ decline → by middle age, NAD+ levels in key tissues drop to roughly 50% of youthful levels
NAD+ decline → mitochondrial dysfunction → neurons can’t produce sufficient energy
Energy deficit → impaired protein clearance → amyloid-beta and tau accumulate
Accumulated toxic proteins → neurodegeneration → cognitive decline, memory loss, dementia

If step 1 drives steps 2–4, then restoring NAD+ at step 1 should, in theory, slow or prevent the cascade. That’s the therapeutic hypothesis — and it’s supported by strong preclinical evidence.

What the Nature Aging Review Found

The review consolidates years of laboratory and clinical research on NAD+ augmentation for neurodegenerative conditions. Key findings:

Preclinical Evidence: Strong and Consistent

Across multiple animal models, NAD+ restoration (via precursors NR and NMN) has been shown to:

Improve mitochondrial function in neurons, restoring energy production to near-youthful levels
Reduce neuroinflammation — the chronic brain inflammation that drives neurodegeneration
Enhance clearance of toxic proteins (amyloid-beta plaques and tau tangles) through improved autophagy
Protect dopaminergic neurons in Parkinson’s models, preserving motor function
Improve cognitive performance in Alzheimer’s mouse models, including memory and spatial learning tasks

These results have been replicated across multiple independent laboratories. The preclinical case is among the strongest in the NAD+ field.

Clinical Trials: Early But Encouraging

Human data is less mature but building:

NR for Mild Cognitive Impairment (MCI): A randomized, placebo-controlled trial tested nicotinamide riboside (1,000 mg twice daily) in older adults with mild cognitive impairment — the stage often preceding Alzheimer’s. The trial found that NR safely increased NAD+ levels and showed trends toward cognitive improvement, though the study was underpowered for definitive conclusions.⁴

NR and Alzheimer’s Biomarkers: A 2025 study published in Alzheimer’s & Dementia: Translational Research & Clinical Interventions examined the effects of oral NR supplementation on cognitive function and Alzheimer’s disease biomarkers in older adults with subjective cognitive decline and MCI. The researchers reviewed existing literature on AD pathophysiological pathways and the potential benefits of NR from both animal models and human trials, finding a biological rationale for NAD+ restoration in early-stage disease but calling for larger confirmatory trials.⁵

Norwegian Clinical Trials: The University of Oslo team behind the Nature Aging review is conducting ongoing clinical trials in Norway testing NR and NMN in patients with neurodegenerative conditions. Results are expected to be published throughout 2026–2027.

What the Review Gets Right

The paper’s most valuable contribution is its restraint. Rather than declaring NAD+ a cure for Alzheimer’s, the 25+ authors explicitly acknowledge:

Dose optimization is unresolved — we don’t yet know the right dose for neuroprotection
Long-term safety data is limited — most trials run 8–12 weeks; neurodegenerative diseases develop over decades
Individual variability is significant — genetic differences in NAD+ metabolism affect how people respond
Animal-to-human translation is uncertain — mouse models of Alzheimer’s have a notoriously poor track record of predicting human efficacy

As lead author Dr. Jianying Zhang stated: “Fine-tuning NAD+ metabolism holds promise for delaying age-related health decline… but to truly unlock its potential, we need to better understand the right doses, long-term safety, and interindividual variability in response to NAD+ augmentation strategies.”¹

This is the honest position: biologically compelling, preclinically supported, clinically promising but unproven.

How This Connects to Longevity Clinics

The Nature Aging review validates something longevity clinics have been doing for years: offering NAD+ therapy as part of their protocols. But it also highlights the gap between clinical practice and clinical evidence.

Of the 55 clinics in our directory, 11 currently offer NAD+ IV therapy. Several — including Progevita in Valencia, SHA Wellness Clinic in Spain, and Chi Longevity in Bangkok — include NAD+ as a standard component of their residential longevity programs.

The question patients should ask when a clinic offers NAD+ for “brain health” or “cognitive optimization” is: what’s the protocol, and what evidence supports it?

Reasonable clinic approaches:

IV NAD+ as part of a comprehensive diagnostic program — if you’re already doing a full health assessment, adding NAD+ therapy is a reasonable “opt-in” based on the strong preclinical rationale
Oral NR/NMN as a daily supplement protocol — supported by the most clinical trial data, lowest risk, lowest cost
Combination approach — IV loading during a clinic visit, oral maintenance thereafter

Red flags:

Claiming NAD+ “reverses” or “cures” Alzheimer’s — no human evidence supports this
Extravagant dosing without rationale — more NAD+ is not necessarily better; dose-response relationships in humans are not established
No baseline diagnostics before NAD+ therapy — comprehensive metabolic panels, cognitive assessments, and ideally brain imaging should precede any NAD+ protocol targeting neuroprotection

For a full breakdown of IV vs. oral NAD+ options, dosing, and costs, see our NAD+ Therapy Guide: IV Infusions vs Oral Supplements.

The Bigger Picture: NAD+ as a Neuroprotective Strategy

The Nature Aging review arrives at a pivotal moment for the NAD+ field. Three concurrent developments are accelerating interest:

1. Pharmaceutical investment. As we covered in our Eli Lilly–Insilico analysis, Big Pharma is now investing billions in aging-targeted drug discovery. NAD+ pathway modulation is one of the most advanced targets in this pipeline.

2. Biomarker advances. New NAD+ measurement techniques (including blood-based assays that can track intracellular NAD+ levels more accurately) are making clinical trials more precise and interpretable. The old criticism — “you can raise NAD+ in blood but not in the brain” — is becoming addressable with newer imaging and metabolomic tools.

3. Alzheimer’s treatment failures. The repeated failure of amyloid-targeting drugs (aducanumab, lecanemab) to produce meaningful cognitive improvement has pushed researchers toward upstream interventions — targeting the metabolic and inflammatory environment that allows amyloid to accumulate in the first place. NAD+ restoration fits this paradigm perfectly.

What Patients Should Do Now

If you’re concerned about cognitive decline — whether you have a family history of Alzheimer’s, are experiencing subjective cognitive decline, or simply want to be proactive:

1. Get comprehensive diagnostics. Before any NAD+ protocol, establish your baseline. A full metabolic panel, cognitive assessment, APOE genotyping, and inflammatory markers. Clinics like Human Longevity Inc. and Fountain Life specialize in this kind of deep baseline assessment.

2. Start with oral NR. The evidence base for oral NR (Niagen®) is stronger than for IV NAD+ or NMN. It’s FDA GRAS, affordable ($40–$100/month), and has the most human safety data. 300–1,000 mg/day is the typical range used in clinical trials.

3. Consider IV NAD+ if you’re already at a clinic. If you’re doing a residential program at a clinic that offers NAD+ IV, adding it to your protocol is reasonable — but don’t choose a clinic solely for NAD+ IV based on current evidence.

4. Prioritize exercise. High-intensity exercise increases brain NAD+ levels and has stronger evidence for cognitive protection than any supplement. This isn’t exciting advice, but it’s the most evidence-based.

5. Watch the trials. The Norwegian NR trials for neurodegeneration will report in 2026–2027. If they’re positive, the evidence landscape will shift significantly. Subscribe to updates from our clinic directory for ongoing coverage.

This article reflects published evidence as of April 2026. NAD+ therapy for neurodegenerative disease is not FDA-approved. Consult a neurologist before starting any NAD+ protocol, particularly if you have a diagnosed neurodegenerative condition.

ScienceDaily, “Scientists say NAD+ could slow aging and fight Alzheimer’s and Parkinson’s.” March 24, 2026. Reporting on expert review published in Nature Aging, 2026. sciencedaily.com ↩ ↩²
Yoshino, J. et al., “NAD+ intermediates: The biology and therapeutic potential of NMN and NR,” Cell Metabolism 27(3), 513–528 (2018). doi:10.1016/j.cmet.2017.11.002 ↩
Lautrup, S. et al., “NAD+ in Brain Aging and Neurodegenerative Disorders,” Cell Metabolism 30(4), 630–655 (2019). doi:10.1016/j.cmet.2019.09.001 ↩
Brakedal, B. et al., “A randomized placebo-controlled trial of nicotinamide riboside in older adults with mild cognitive impairment,” Nature Communications 15, 1318 (2024). doi:10.1038/s41467-024-45421-4 ↩
Wu, Y. et al., “Cognitive and Alzheimer’s disease biomarker effects of oral nicotinamide riboside supplementation in older adults with subjective cognitive decline and mild cognitive impairment,” Alzheimer’s & Dementia: TRCI (2025). doi:10.1002/trc2.70023 ↩