New study indicates that a decrease in nerve cell cholesterol caused by cortisol, inflammation & low SIRT1 activity may be a cause of major depression.
So, do statins exacerbate depression?
And since SIRT1 is NAD⁺-dependent, could NAD⁺ boosters treat or prevent depression? …🧵
Around 5–5.7% of adults worldwide experience depressive disorders at any given time. >280 million people!
Lifetime depression diagnoses in the U.S. have risen. ~29% report ever being diagnosed, up from ~20% a decade ago
Using human stem cell–derived prefrontal cortex neurons, the authors modeled 3 major risk factors: chronic cortisol (stress), interferon-α (inflammation), and loss of SIRT1, a longevity-linked NAD⁺-dependent deacetylase
Strikingly, all three caused the same phenotype: dendritic atrophy, synapse loss, reduced glutamate signaling, and neuronal hypoactivity
SIRT1 loss alters expression of cholesterol synthesis & transport, reducing membrane cholesterol and impairing synaptic function. This links metabolism, epigenetics, and mood
Lowering cholesterol in healthy neurons reproduced depression-like defects. Conversely, restoring cholesterol rescued synapses and glutamate responses across all models
This study raises a testable idea: could NAD⁺ precursors (NR, NMN, etc.) help restore SIRT1 activity, normalize neuronal cholesterol, and improve synaptic function in subsets of major depressive disorder?
NMN has been reported to improve depression-like behaviors in stress/corticosterone models in mice. Translation to humans is not known
There are mouse studies suggesting another NAD precursor NR can reduce depression-like behaviors in specific contexts
In my experience, NMN has improved my mood over the past 15 years - and clinical trials should be initiated to test it
As to whether statins are a risk: possibly. Brain cholesterol is largely synthesized locally (by neurons and especially astrocytes). Peripheral cholesterol does not cross the blood–brain barrier in meaningful amounts
Lipophilic statins (e.g., simvastatin, lovastatin, atorvastatin/Lipitor) can cross the blood brain barrier. Hydrophilic statins (e.g., pravastatin, rosuvastatin/Crestor) cross poorly
Some studies show statins associating with depressive symptoms while others show no effect or even benefit (likely via anti-inflammatory or vascular effects)
A subset of individuals may be vulnerable to cholesterol-lowering drugs, especially if brain cholesterol or SIRT1/NAD⁺ are already altered by genetics, age, or disease
ED drugs like Cialis & Viagra, when taken as a low dose daily, can help maintain vascular function in brain and muscle, and are a promising, though still debated, approach for preventing & treating dementias. The human data for Cialis (tadalafil) is stronger …🧵
Preclinical (🐁) evidence consistently supports the neuroprotective and cognitive-enhancing effects of PDE5-Is. Large-scale clinical datasets also suggest potential benefit journals.sagepub.com/doi/10.3233/AD…
However, findings remain inconsistent, likely due to methodological limitations such as small sample sizes, insufficient treatment durations & heterogeneous patient populations
In my 20s and 30s, I didn’t realize that criticism is actually a positive sign. It’s easy to see in retrospect, but those days were incredibly tough for all of us in the Sinclair lab and a lesson for everyone who’s looking to change the world
First big discovery:
DNA instability & epigenetic changes are a universal cause of aging (1996-1999). Critics immediately said we were wrong but we pushed on
So great to see the OG work that helped spark the longevity revolution taken to the next level:
New paper confirms two main causes of aging: 1. DNA instability -> epigenetic noise 2. Mitochondrial decline
...independently causing failure of the cell
Is this relevant to us? 🧵
Firstly, Dan Gottschling is a legend, having discovered yeast epigenetic gene silencing at the gender genes (a/alpha), telomeres, and painfully scooped me as a postdoc in 1996 by publishing epigenetic silencing at the ribosomal DNA (rDNA) 😆 ...
In my postdoc with Leonard Guarente in the 1990s, we predicted (below in my notebook) then confirmed something strange in aging yeast: tiny circles of "extrachomosomal" DNA accumulating inside old cells
Osteoarthritis & back pain affects millions of people. Instead of managing symptoms, imagine rebuilding joints by making them young
New study shows the reprogramming gene combo OSK regrows joints in mice & effect depends on TET2 so it's epigenetic...🧵
While limited to mouse models, these findings add to a growing body of evidence that rejuvenation by epigenetic reprogramming may safely reverse aging-related decline in multiple tissues, or whole body one day
These experiments used local AAV-OSK delivery directly into the knee joint. Treated animals showed improved cartilage structure and reduced subchondral bone thickening compared with controls
According to ITOA, NAD declines with age, causing epigenetic changes & disease susceptibility
In 2010, we showed NAD-dependent enzyme, SIRT3, protects the heart 🐁
New study says NAD precursor NMN protects the heart via SIRT3 in mice fed a Western diet
Why's that important? 🧵
In the United States alone, about 1 in 5 deaths is due to cardiovascular disease. That’s roughly 700K-900K deaths per year. Globally, cardiovascular disease causes nearly 20 million deaths annually
Metabolic dysfunction is a major driver. In the US, ~40 percent of adults are obese and nearly 1 in 3 adults has metabolic syndrome
Globally, more than 500 million people are living with diabetes
Good news: Another study showing that fasting can help cancer patients. A 16 hour fast enhanced the cancer-killing activity of T cells and synergized with immunotherapy to reduce tumor size, ostensibly by causing cancer cells to release the amino isoleucine... 🧵
In the tumor microenvironment (TME), there was increased isoleucine processing and intracellular acetyl-coA, along with increase expression of genes involved in the starvation response, autophagy
There were also alterations in glutamine metabolism, a known source of energy for cancer cells