For years, depression was largely discussed as a disorder of mood: persistent sadness, hopelessness, loss of interest and a lack of motivation. But that description is increasingly incomplete. Depression is not confined to the emotions. It can affect sleep, memory, concentration, energy, appetite, hormones, inflammation and the way the brain processes information. Research is now also finding an intriguing connection between major depression and biological ageing, raising a difficult question: can depression make a person biologically older than their chronological age?
The answer is not as simple as saying that depression gives you extra wrinkles or literally adds years to your brain. The science does not support such a sweeping conclusion. What it does show is that people with major depressive disorder can exhibit changes in several biological systems that are also involved in ageing. These include changes in stress regulation, inflammation, cellular ageing, brain structure and cognitive performance. Taken together, these findings suggest that prolonged or severe depression may affect some of the same biological pathways that become increasingly important as we grow older.
Depression and the biology of ageing
One of the most interesting developments in this area has been the ability to measure biological age rather than simply counting someone’s years. Chronological age is straightforward: if you are 35, you have lived for 35 years. Biological age is an attempt to determine how old the body’s biological systems appear to be based on measurable changes in cells and tissues.
Scientists can estimate biological age using what are known as epigenetic clocks. These examine patterns of DNA methylation, chemical modifications that influence how genes are expressed and that change as we age. Some of these clocks have been developed to estimate mortality risk and the pace of biological ageing.
A 2021 study published in Translational Psychiatry examined people with major depressive disorder and healthy controls using the GrimAge epigenetic clock. The researchers found evidence of greater age acceleration among people with major depression, with the difference in their sample amounting to roughly two years of excess cellular ageing. The finding does not mean that every depressed person is biologically two years older, nor does it establish that depression directly caused the difference. What it does demonstrate is that measurable biological markers associated with ageing were shifted in the direction of accelerated ageing among people with major depression.
More recent research has taken this question further. A 2025 multi-omics study using large datasets examined the relationship between major depressive disorder and proteomic ageing, essentially looking at patterns of proteins associated with biological ageing. The researchers reported associations between a history of major depressive disorder and accelerated systemic and brain-specific proteomic ageing. They also found that some of these relationships were associated with depression remission, adding to the possibility that the relationship between depression and biological ageing is not necessarily a permanent, one-directional process.
This is important because it changes the way depression can be understood. The question is no longer simply whether a person feels older when they are depressed. Researchers are finding measurable biological differences that may help explain why someone experiencing prolonged depression can feel physically and cognitively older than they actually are.
But can depression make you look older?
This is where the story becomes more complicated. There is not enough evidence to say that depression directly causes facial ageing in the same straightforward way that ultraviolet radiation or chronological ageing does. However, depression can influence a number of processes that are known to affect physical appearance.
Sleep is an obvious example. Depression commonly disrupts sleep, whether through insomnia, fragmented sleep or excessive sleeping that does not leave a person feeling restored. Research into sleep deprivation has found that insufficient sleep can change how faces are perceived, making people appear more tired, less healthy and older. A systematic review of skin-ageing research has also identified psychological stress and poor sleep among factors associated with visible changes in skin appearance.
The body’s stress-response system may provide another connection. Depression has been associated with changes in the hypothalamic-pituitary-adrenal axis, the system responsible for regulating the body’s response to stress. Cortisol is an essential hormone, but persistent dysregulation of the stress system can have consequences throughout the body. Research has found altered cortisol patterns in people with depression, particularly in some older populations.
Chronic psychological stress can also affect the skin through several biological pathways, including inflammation, oxidative stress and changes to the skin barrier. This does not mean that every line on a person’s face is caused by depression. It means that prolonged psychological distress can occur alongside biological processes that influence how healthy and rested the skin appears.
There is also the behavioural component. Someone experiencing depression may stop exercising, eat poorly, lose or gain significant weight, spend less time outdoors, neglect skincare or personal grooming, and develop unhealthy coping behaviours. None of these changes is inevitable, but when several occur simultaneously over months or years, the cumulative effect can be visible.
This is why the relationship between depression and appearance should not be reduced to the claim that “depression causes wrinkles.” The more scientifically defensible explanation is that depression can affect sleep, stress physiology, inflammation, physical activity, nutrition and self-care, all of which can influence how a person looks and feels.
What depression can do to the brain
The more substantial evidence concerns the brain itself.
People experiencing depression frequently describe what is sometimes called “brain fog”: difficulty concentrating, forgetting things, struggling to make decisions or feeling as though their thoughts are moving more slowly than they used to. These experiences are not simply imagined consequences of feeling sad. Cognitive research has repeatedly identified measurable difficulties in people with major depressive disorder.
A systematic review examining executive function and information-processing speed in major depression found evidence of impairments in areas including processing speed, attention, memory and executive functioning. These are fundamental cognitive abilities that allow us to plan, concentrate, solve problems, remember information and respond appropriately to changing circumstances.
Another large meta-analysis examining cognitive control across the lifespan included more than 16,000 participants from 76 studies. The researchers found that both clinical depression and subthreshold depressive symptoms were associated with deficits in cognitive control, with the relationship becoming particularly apparent in older populations.
This matters because cognitive control is not some obscure laboratory function. It is involved in everyday activities. When you decide what needs to be done, resist a distraction, switch between tasks, remember what you were doing or maintain concentration during a conversation, you are relying on these systems.
Depression can therefore make ordinary mental tasks feel disproportionately difficult. A person may know exactly what they want to do but struggle to initiate it. They may read the same paragraph several times without absorbing it. They may walk into a room and forget why they went there. They may take considerably longer to make decisions that previously required very little thought.
These changes can be particularly frightening because people sometimes interpret them as evidence that they are permanently losing their mental abilities. In many cases, however, cognitive symptoms are part of the depressive illness itself, and their persistence and severity can vary.
Depression is also associated with changes in brain structure
Researchers have also used MRI scans to investigate whether depression is associated with physical differences in the brain.
A 2019 systematic review and meta-analysis examining cortical thickness in major depressive disorder analysed dozens of studies and found evidence of cortical thinning in several regions, including parts of the orbitofrontal cortex.
The orbitofrontal cortex is involved in decision-making, emotional regulation and evaluating rewards and consequences. Other research has identified associations between depression and changes involving regions such as the anterior cingulate cortex and hippocampus, areas involved in emotional processing, memory and cognitive regulation.
But this is an area where scientific precision matters. It would be misleading to tell someone that depression simply “shrinks the brain.” Brain imaging studies do not show that every person with depression develops the same structural changes. Some studies find associations that are small, inconsistent or dependent on the severity, duration and characteristics of the illness.
A large pooled analysis involving thousands of participants found associations between depression and structural differences in certain brain regions, but these effects were not consistently observed across every population studied. The researchers specifically noted differences between clinical samples and broader population-based samples in which depressive symptoms tended to be milder.
So the evidence supports a more careful conclusion: clinically significant depression is associated with measurable differences in brain structure and function in some people, particularly in areas involved in emotion, memory and cognitive control. That is very different from claiming that depression inevitably causes permanent brain damage.
The connection between depression, inflammation and cellular ageing
One reason scientists are interested in depression as a potential contributor to biological ageing is that the two conditions share several biological mechanisms.
A 2022 review published in Ageing Research Reviews examined the overlap between major depression and the recognised biological hallmarks of ageing. The researchers discussed common pathways involving chronic inflammation, oxidative stress, mitochondrial dysfunction, cellular senescence and changes in cellular repair and stress responses.
These systems are important because the body is constantly repairing itself. Cells experience damage, energy systems need to be maintained, damaged proteins need to be cleared and inflammation needs to be controlled. As we age, some of these processes become less efficient. If depression is associated with persistent changes in some of the same pathways, it could help explain the connection researchers are seeing between depression and accelerated biological ageing.
Telomeres provide another piece of the puzzle. These protective structures sit at the ends of chromosomes and generally become shorter as cells divide. Telomere length is not a perfect biological-age measurement, but researchers have investigated whether it relates to brain health and cognition.
A systematic review and meta-analysis examining telomere length and brain ageing found associations between longer leukocyte telomeres and larger brain volume, larger hippocampal volume and better global cognitive performance. The study also found associations with attention, processing speed and executive function.
Again, this does not mean that depression simply shortens telomeres and therefore causes cognitive decline. Human ageing is considerably more complicated than that. But it demonstrates why researchers increasingly view mental health, cellular health and brain ageing as interconnected rather than completely separate subjects.
The question of “brain age”
The phrase “brain age” has become increasingly popular because researchers can use MRI data and statistical models to estimate how old a person’s brain appears compared with other people of the same chronological age.
Some studies have found an increased brain-age gap among people with depression. One influential neuroimaging study reported that adults with major depression showed evidence of older-appearing brains compared with their chronological age, with the estimated difference being several years in that particular sample.
But brain-age estimates should not be interpreted literally. If a computer model estimates that a 40-year-old has a brain age of 44, that does not mean their brain has physically travelled through four additional years of biological development. It means that the pattern of features measured by the model resembles, statistically, patterns more commonly observed in older individuals.
There are also studies that have failed to find evidence of accelerated epigenetic ageing in brain tissue from people with major depression. This apparent disagreement is actually useful because it demonstrates that “biological age” is not one single thing. Different studies measure different processes, and those processes do not necessarily change at the same rate.
The science is therefore pointing toward a relationship between depression and ageing without yet providing one simple measurement that can tell us exactly how much depression has “aged” an individual’s brain.
Perhaps the most important question is whether the process can change
The most encouraging part of this research is that scientists are not simply finding evidence of damage and stopping there.
Depression is treatable. And some of the research into biological ageing suggests that the relationship may be more dynamic than the idea of permanent deterioration implies.
The 2025 multi-omics study found that remission of depressive episodes was associated with attenuation of some of the relationships between major depression and accelerated systemic ageing.
This does not prove that treating depression reverses biological ageing. It would be premature to make that claim. But it does challenge the idea that biological changes associated with depression necessarily represent an irreversible process.
That distinction is enormously important.
A person who has spent several years depressed may notice that they no longer look or feel like themselves. Their sleep may be poor, their energy may be low, their concentration may have deteriorated and their motivation may have disappeared. They may look tired and feel mentally slower. It can be tempting to interpret all of this as evidence that they have somehow permanently aged.
The research suggests a more complicated — and potentially more hopeful — explanation.
Some of these changes may reflect the biological consequences of the depressive illness itself, combined with disrupted sleep, chronic stress, inactivity, changes in nutrition and other factors. Addressing the underlying depression and restoring healthier patterns may therefore have effects that go well beyond simply improving someone’s mood.
Depression deserves to be understood as a whole-body condition
Perhaps the biggest mistake we can make when discussing depression is to treat it as nothing more than sadness.
Depression can affect the way a person sleeps, eats, moves, thinks, remembers, concentrates and responds to stress. It can alter the functioning of biological systems throughout the body and is increasingly being studied in connection with the molecular processes of ageing.
That does not mean depression inevitably causes permanent brain damage. It does not mean every depressed person will develop accelerated biological ageing. It does not mean that every visible sign of ageing on someone’s face can be attributed to depression.
But the evidence does support something much more significant than the old idea that depression is simply a state of feeling unhappy.
Depression can affect the machinery of the brain and body.
And when a condition can influence cognition, stress regulation, inflammation, sleep, brain structure and biological-age markers, it deserves to be treated with the same seriousness we give other chronic conditions.
The person who says, “I don’t feel like myself anymore,” may not simply be describing an emotional experience. They may be describing changes occurring across several interconnected biological systems.
The emerging science is telling us that the mind and the body were never separate in the first place. Depression is one of the clearest examples of just how deeply the two are connected.
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