Illustration created with AI image tools.
A man in his late forties comes to see me after twenty-five years of drinking and smoking. His labs are mostly fine and he still holds down a job. He tells me his memory is slipping and that he can't hold a plan together the way he used to, and he asks whether he has damaged something permanently. For most of my career I could only answer with what I'd seen in patients. A large imaging study in PLOS Medicine now gives me numbers to go with it.
What the study measured
Shile Qi and colleagues at Nanjing University of Aeronautics and Astronautics pooled structural MRI scans from 45,900 healthy controls and 2,698 people with one of nine conditions. They trained a model to estimate how old a brain looks from its structure alone, then compared that estimate with the person's actual age. The gap is called the predictive age difference. A positive number means the brain looks older than the calendar says it should.
Alzheimer's disease showed the largest gap, with an effect size (Cohen's d) of 0.97. Mild cognitive impairment came in at 0.45. Alcohol and tobacco addiction together came in at 0.84, tobacco addiction alone at 0.72, and alcohol addiction alone at 0.62. Schizophrenia was 0.53, bipolar disorder 0.46, and major depression 0.28. ADHD and autism showed essentially no gap.
Read that list again, because the ordering is the finding. In this dataset, the brain of a person with combined alcohol and tobacco addiction deviated from the healthy aging curve almost as much as the brain of a person with Alzheimer's disease, and more than the brains of people with schizophrenia or bipolar disorder.
Where addiction shows up in the brain
Different conditions aged different regions. Dementia concentrated in frontal and occipital cortex. The psychiatric disorders leaned on frontal and temporal regions. Addiction pointed at the default mode network, the salience network, the putamen, and the thalamus.
Those are the circuits I talk about with patients every week. The salience network decides what deserves your attention, and in addiction it learns to rank the drug above nearly everything else. The putamen helps run habit. The thalamus relays signals between nearly every part of the cortex. When the structural scan shows these areas looking older than they should, it lines up with what people describe in my office: cravings that override good judgment, a flat response to ordinary pleasures, and trouble with planning and attention that outlasts the last drink.
This is also why the old story about weak character never held up. Nobody chooses to have a thalamus that looks older than its owner. The scan finds tissue that has been physically changed by exposure, and I see that as a medical problem to be treated.
What this study cannot tell us
The design is cross-sectional and correlational, so it cannot say whether substance use caused the older-looking brains or whether some people with older-looking brains were more likely to become addicted. Alcohol and tobacco use are also tangled up with depression, poor sleep, and cardiovascular disease, and the authors note that psychiatric comorbidity may confound some of the results. Effect sizes in a group comparison also say nothing certain about any one person's scan. And a brain age score is a research tool right now. It is not something I can order for a patient and read as a verdict.
What I take from it is the direction of the evidence. A structural measure that has nothing to do with a person's self-report, their willingness to answer honestly, or their history with treatment still picks out addiction as a condition that affects the brain broadly.
What this means for recovery
Brain age gaps are not fixed. Earlier work on abstinence has shown partial structural recovery in people who stop drinking, and I would expect the same logic to apply to tobacco, although this particular study did not test it and I would not promise a patient any specific amount of reversal. What I do tell people is that the brain responds to what you give it after you stop. Sleep, exercise, adequate protein and micronutrients, and treatment of coexisting depression or anxiety all have a role. Brain nutrition is one area where our colleagues at Action Potential Supplements have focused their formulation work, and I'd rather see a patient get the basics right than chase a single compound.
If you or someone you love has years of heavy drinking or smoking behind them and has noticed changes in memory or planning, it is reasonable to ask a physician for a cognitive evaluation and, where it makes sense, brain imaging. Our Rescue From Rehab program starts from that premise: that recovery means rebuilding brain function, which is more than getting through withdrawal, and that the workup should measure it. I wrote about a related finding earlier this month in Heavy Drinking at 25 Already Shows Up in the Blood, and the two studies point the same way.
The brain you have today is not the brain you are stuck with, and a scan that shows damage is a place to start treatment from. It says nothing about who you are.
This article was drafted with the assistance of AI writing tools, then reviewed, edited, and approved by Dr. Drew W. Edwards, Ed.D, who holds full editorial responsibility for its content.
Source: Qi S, et al., PLOS Medicine, 2026 (45,900 controls and 2,698 patients across nine conditions). Coverage: Neuroscience News; ScienceDaily.