‘There Is No Health Without Mental Health’: The Depression and Brain Health Link

Is there a connection between brain health and depression? Treating depressive symptoms early in life may not only improve your mental health, but could also prevent you from experiencing rapid cognitive decline later in life. Darya Gaysina, Ph.D., a developmental psychologist from the University of Sussex, analyzed 34 studies on the connection between brain aging and depression.

She found that individuals who experienced depressive symptoms at the start of each study experienced a decrease in their cognitive state over a six-year period that was 35 percent faster than those who did not have these symptoms at the beginning. Could treating depression as early as possible improve brain health later in life?

• Both a clinical diagnosis of depression and depressive symptoms could lead to more rapid cognitive decline
• Symptoms of depression such as hopelessness, loss of concentration, energy, sleep or interest in activities you normally enjoy are signs there could be something wrong with your brain
• Depressive symptoms may be caused by stress rather than depression, since chronic stress has been shown to shrink the hippocampus and amygdala, the areas of the brain that are responsible for regulating memories and mood
• Treating depressive symptoms early may improve cognitive issues, including loss of concentration

Being Patient spoke to Gaysina about her research on the link between depression and dementia, what happens to the brain when someone is depressed, how environment or genetics could lead to depression, why researchers think depression may lead to Alzheimer’s and why looking after your mental health when you are young is important.

Being Patient: Can you tell us about your recent study on the link between depression and dementia?

Darya Gaysina: Research has shown that depression and dementia are related—particularly in older adults. Older adults with symptoms of depression are shown to be at an increased risk of developing dementia and Alzheimer’s disease in particular. Less is known about how depression may affect brain aging in the normal population, or the population that is free of dementia.

We wanted to see whether depression can also predict how fast our brain ages or how fast our cognitive function can decline. Age is a major risk factor for cognitive aging; we all have a decrease in our cognitive function as we age. By cognitive function, I mean our ability to concentrate, focus on particular tasks or remember certain events or words. Our memory, concentration and executive function can be impaired with age. We wanted to find out what has already been studied in relation to cognitive aging in people with depression. We looked across different research databases using a set of criteria that tried to address this important question. We looked at 25,000 different studies and identified 34 studies that either measured depression at the baseline as a disorder, or measured the symptoms of depression as a baseline. By baseline, I mean Time 1, or the first time researchers looked at participants. We also looked at the outcomes that these studies reported on. The outcomes were a decline in participants’ cognitive state. Someone’s cognitive function can include memory, concentration, attention, decision making and various things.

It’s known that with age, all of these functions can decline. What we found by combining the evidence from 34 studies was evidence that if the person experiences depression at Time 1, in the following years—the average period was about six years—there was a decrease in their cognitive state. It’s a faster decrease: approximately 35 percent faster than for the person without depression at this baseline of Time 1. We also showed that it’s not only clinically diagnosed depression that puts people at an increased risk of faster cognitive decline, but also depressive symptoms. Even if the person doesn’t have the clinically diagnosed disorder of depression, but has an increased level of depressive symptoms, it also presents a risk factor for faster cognitive decline.

Being Patient: Is cognitive decline causing people to feel depressed or is having depression speeding up brain aging?

Darya Gaysina: You’re absolutely right, it’s called the chicken or egg problem. It’s very difficult to find the direction in which this link operates and it could be that depression accelerates cognitive aging. It could be that our brain age in itself is a risk factor for developing depression. I think these two processes are not mutually exclusive. I think this link could operate in both ways. What we also need to keep in mind is that there is a third factor that could lead to the development of depression and impaired cognitive function or faster cognitive decline. It could be something else unrelated to both of these independently, for example, stress. Stress could pose a risk for our mental health, cognitive health and physical health as well.  

Being Patient: What changes happen in the brain when someone is depressed?

Darya Gaysina: When you experience periods of low emotion it doesn’t actually mean that you are depressed. One of the main symptoms of depression is the low emote, so you may also feel hopelessness or lose interest in the things you are normally interested in, like meeting with friends, going for a walk or spending time engaging in different kinds of activities. There are three main symptoms or signs of depression and if you experience them for a long time—by a long time, I mean weeks or months—it’s a sign that you may have depression. There are also different symptoms that people can experience and it varies from one person to another. There are some physical symptoms, like loss of concentration, energy or appetite and problems with sleep. There are also some psychological symptoms, such as inability to work on a specific task.

These changes can be signs that something is wrong with the brain as well. Again, it’s very difficult to say whether it’s depression that damages our brain or whether some underlying processes in the brain can put people at risk for experiencing these symptoms. Other research has shown that there are certain regions of the brain that are particularly affected in people with depression. Two of these regions have the most evidence up-to-date. One of these regions is called the amygdala; this is the region that is particularly important in regulating our mood. The second region relates to our question about depression and cognitive decline: the hippocampus. This is the region that plays an important role in storing our memories. And when you’re depressed, it’s more likely that you have an impaired ability to regulate your mood and cognitive functions, including memory, that could be directly linked to this area of the brain: the hippocampus. What is known is that if you experience depressive symptoms or depression for a prolonged period of time, it could also be due to stress. You’re not depressed, but you’re stressed all the time, so it’s called chronic stress. Then, this area of the brain can shrink. It becomes less efficient in performing the specific task that it is designed for, like remembering events and names, for example; that’s one of the possible biological mechanisms that may underline the link between depression and the cognitive disability of dementia.

Being Patient: Often, Alzheimer’s is mistaken for depression or vice versa. How can you tell if an older loved one is just suffering from depression or if they are in the early stages of the disease?

Darya Gaysina: I think the only possibility to distinguish between these two in older adults is to seek professional help. Talk to your doctor to find out more. There are specific diagnostic tools that could be used to identify and target either of these or both. It’s a very important preventive measure, so you can definitely improve the symptoms of depression with cognitive behavioral therapy or medical treatments, such as antidepressants. It could definitely improve memory function as well in many older patients. It could be either one or another. It could be both, so that’s why it’s important to seek professional help if necessary.

Being Patient: Can people be genetically predisposed to depression?

Darya Gaysina: The consensus among researchers is that it is 50 percent genetic factors and 50 percent environmental factors in relation to depression. I think that people misunderstand what that means. We say that there is a genetic reason for depression. We’re talking about genetic predisposition or genetic risk for depression. Risk means it could put the person in a particularly vulnerable position to develop depression, but this risk is not unavoidable. If you have a genetic risk for depression, it doesn’t necessarily mean that you will develop depression. This will depend on other factors as well: environmental and social factors. It will not only depend on your genetic risk factors. There are probably multiple genes—thousands of genes—that could contribute to an increased risk of depression and each of these genetic variants will contribute a very small proportion to this risk. You may have multiple genetic risk markers; in combination, they will increase your risk for depression in a small proportion, but it basically all depends on your environment—whether you develop depression or will be fine. The message here is that even if you have a family history of depression, you shouldn’t just think you will develop depression at some point in your life. Yes, you are at an increased risk if you have a family history of depression, but the risk is not unavoidable. There are multiple ways that you can look after your mental health, improve it and protect yourself against cognitive decline.

Being Patient: What environmental factors have you identified that may predispose someone to depression?

Darya Gaysina: It’s really tricky if we want to talk about genetic factors for depression because there is no single factor that will define whether the person develops depression. Researchers just started to identify the factors that have a tiny contribution to depression and as I said, there are thousands of these factors. So even if you have one, two or three factors like this, it’s a very small risk in relation to depression, so we have to wait and see how many more factors people will be able to identify and how, in combination, in the future, we can use this information to predict the risk for depression in individual people. For now, there is no genetic tool that could be used to identify the risk for depression on the genetic scale.

But yes, there are a lot of environmental factors that have been looked at and identify the risk factors for depression. I think the risk factors can vary. The most serious and strong risk factor for depression is chronic stress. It’s a very bad factor for many mental, physical and cognitive health problems. Our bodies are designed to deal with stress within a very short period of time; we’ve all experienced stress in our everyday lives. Public speaking is very stressful because we’re not designed to be exposed to other people. We want to see how a situation develops. But then after a certain amount of time, we see the audience, that they are friendly and not going to attack us, so our body relaxes. It’s the first moment of stress that the brain sends a signal to the body to make sure the body is prepared for the fight or flight situation. It’s very good for us because we perform better under conditions of short-term stress. If we experience stress all the time, then the brain will signal to our body that there is stress and our body becomes imbalanced. There is a specific stress hormone that regulates how we react to stress and in certain situations, when we are under chronic stress, this hormone cannot signal effectively to our brain and to other systems in our body. The whole body becomes imbalanced and it is very bad.

There are certain techniques that can help us to get back to normal. For example, meditation and mindfulness techniques are very good methods for dealing with stress. They work for some people, but they may not work for everyone. There is quite strong evidence in the literature that suggests a moderate level of regular physical activity is very good for all systems of our body. It’s good for our brain, mood and cognitive function. You need to find a way to relax your brain and body. Think about something positive, if possible. Find time for yourself, your friends and family, because loneliness is very bad for our mental health.  

Being Patient: Is it worth using medication that could help with depressive symptoms and would the medication offset any potential damage to the brain?

Darya Gaysina: I think whether you need antidepressants or not should be discussed with medical professionals because there are a whole variety of medications available, so you shouldn’t make the decision on your own. Also, medical professionals may advise you to try different therapies first. There are cognitive behavioral therapies that could work for certain people so they don’t have to prescribe them with medication straight away. If the depression is very severe and persistent, medications may be required. I think with all of the medications, there are side effects. Whatever drug we take, there will be some side effects, so that’s why for doctors, it’s important to weigh pros and cons, but antidepressants are known to reverse some of the effects on the brain as well. For example, if we’re under constant stress and our brains start to shrink. There are certain antidepressants that can reverse this process and help our brains to deal with stress and depression, so medication is definitely not bad. For some people, it’s the only way to get better.

Being Patient: You mentioned depression and depressive symptoms. When should someone talk to their doctor about symptoms they are experiencing?

Darya Gaysina: Our body will start signaling that something is wrong. There are multiple symptoms and I haven’t mentioned all of them, but if you experience low emotion and hopelessness for a few weeks or months and can identify some of the other physical or psychological symptoms that were not with you all the time—for example, your anxiety levels can increase and you may struggle to perform everyday tasks, like underperforming on a talk or struggling with a family situation—you have to seek professional help and talk to your family doctor or GP. Find out more about what help is available for you. It’s never too late to look after your mental health. There is no health without mental health.

Being Patient: More research is being done on the effects of meditation. What has been observed in the brains of people who meditate and how can symptoms of depression or stress be mitigated using meditation?

Darya Gaysina: What I know about meditation from the recent literature is that it is shown to help to deal with moderate symptoms of depression and helps the body to relax more. The level of stress hormones decreases. It prevents our brain from getting signals that we’re stressed, so that’s definitely helpful for general and mental health. It’s shown to have positive effects on our immune system as well—another system that can signal to our brain that something is wrong and we’re under a stressful situation. Both the neural and hormonal regulations become more balanced if we meditate regularly. But it may not help everyone. Many people who are used to meditation will tell you that it’s good for your health. It helps you to deal with everyday stress.

Being Patient: What does research show about how treating depression may lower Alzheimer’s risk?

Darya Gaysina: It’s definitely the case. That’s why we urge you to look for signs of depression as early as possible because most of the research so far that looks at how depression is linked to cognitive decline and dementia has been conducted in older adults. Our most recent research that hasn’t been published yet suggests that it’s the symptoms of depression that start much earlier in the life course that may affect our cognitive function much earlier in life as well. So you’re probably looking at a population which is age 60 or above; it’s already too late to pick up this critical period when our cognitive function starts to decline and it starts to decline much faster in those with depression.

When we can prevent depression, it’s great for our physical and cognitive health. Even if we cannot prevent depression, it’s important to start treatment as early as possible and deal with depression as early as possible with cognitive behavioral therapy or medication. Any of these interventions can be good for physical and cognitive health in the long term.

Being Patient: You mentioned depression already impacts cognitive function early in life. What might that look like practically? What are the signs?

Darya Gaysina: Many signs of depression are related to our cognitive abilities, including loss of concentration. That’s one of the signs that, if you observe it, may tell you that you may be depressed. With memory, it’s rare, but normally it’s the later stages that the memory can also be impaired. Once you start treating the depression, some of the symptoms will disappear as well. But if the depression remains untreated, the symptoms can actually worsen and lead to faster cognitive decline much earlier in the life course.

Being Patient: Is that due to changes in the brain?

Darya Gaysina: You’re absolutely right. There are observable changes in the brain structure and brain function for people with depression. Some of these changes may be temporary and once you’re back to normal, the brain areas will start functioning normally and look normal as well. There might be some changes that cannot be reversed anymore. The earlier you start treating depression, the better effect it will have on the brain and on cognitive function later in life.

Being Patient: Does that go back to the idea of neuroplasticity, or the brain’s ability to create new neural connections when learning new things?

Darya Gaysina: Definitely. Our brains have neuroplasticity, so whatever we can do to help our brain return to normal is good. Positive effects of physical exercise have been observed in animal models. It’s more difficult to do the experiments in humans. After experiencing stress, if the animals were made to exercise regularly, the researchers saw positive reversible effects on the brains of these mice and rats.

Being Patient: Is the main message that if you’re experiencing depression, it could affect your cognitive abilities right now and raise your risk of developing dementia later on, but if you intervene early enough and start taking positive steps, you can lower your risk and protect your brain?

Darya Gaysina: Definitely. It’s never too late to start looking after your mental health and to avoid these long-term negative outcomes.