Serotonin and depression

Currently, the lectures of the course are very much concentrated on neurotransmitters. I will use this as an excuse to write about depression and it’s medication.

As everything in neuroscience, depression can be seen from many different perspectives, and combining these gives us a wider field of vision. The perspectives I can offer are the neuroscientific one (based mainly on combination of Bear, Connors & Paradiso and Wikipedia) and the one of personal experience. I was diagnosed with depression last winter. Other useful point of view would be for example that of mental health care professionals’.

In colloquial language, depression has become a synonym of sadness. It is, however, more than that: a serious mental illness. Sadness and low mood are definitely symptoms of depression, but additionally there is for example lack of energy and motivation, a feeling of simple (and even fun and desirable) tasks being impossible to face. Additionally, sadness as a symptom of depression is different than as a regular feeling: it is generally more intense and doesn’t require a direct reason, instead being more like a positive feedback loop of negative emotions. On the other hand, depressed people aren’t necessarily always sad, and one can’t just decide someone is not depressed by just looking at their face.

Psychologically, depression might be triggered by stress or traumatic events, but typically this happens to people who have some kind of (genetic) susceptibility for it. From neurochemical perspective, this seems to be related to the neurotransmitter serotonin. Among other functions, this amine regulates mood.

Selective serotonin reuptake inhibitors, or SSRIs  for short, are one class of antidepressants. There are also other kinds of drugs against depression, but I will discuss only SSRIs here, because they are perhaps the most common kind and I have personal experience on them.

As the name suggests, SSRIs inhibit reuptake of serotonin to cells, increasing its concentration in synaptic cleft. Thus, the first interpretation would be, that SSRIs help the travel of of serotonin-mediated signals that are associated with positive feelings. The truth, however, is not as simple as that.  The anti-depression effects of these drugs take several weeks to really start showing. At that point, the cells have adapted to their presence by reducing the amount of serotonin receptors. It is not clear why this reduces the symptoms. One effect demonstrated is increased neurogenesis in hippocampus.

In addition to the science really not being settled, there is the fact that each individual human is different. There are many different kinds off SSRI drugs. Some of them work for some people and not for others. Some people will experience side effects. Scientific research can usually give us only general ideas. For example, some studies suggest that at least some SSRIs work better for people with more severe depression. For an individual, the only way to see if some specific (clinically approved) drug is suitable is trying it for couple of weeks, seeing how it feels and then possibly adjusting the dosage before waiting again for the effects to take place.

For example, I was first prescribed escitalopram. I felt that it made me more socially initiative, but the symptoms of depression kept getting worse. (At that point I didn’t have the depression diagnosis yet. The initial prescription was for anxiety, for which the SSRI medication is also used.) After I was barely able to handle my studies and other aspects of life even with highest dosage of escittalopram generally in use, I was switched to sertralin. Initial dose for that was also too small, but after a couple of times of adjusting it, the effects became clear. I have energy to study and do things I love. I have a working sleep cycle. I have lots of creative ideas. I feel like I have got my own personality and self back.

The medication isn’t a simple magical cure for depression. SSRIs have their problems. The important thing is that they can give the strength needed for rising from the depression. I have a weekly session with my psychotherapist and do mindfulness exercises to get better understanding and control over my emotions.

From our course book I learned that serotonin is made by cells from tryptophan, which we can get from many kinds of foods, including chocolate. It’s not scientifically proven that more dietary (non-purified) tryptophan leads to more serotonin in the brain, but chocolate can improve the mood in many ways 😉

So, remember to eat chocolate every now and then and please be kind to people with mental illnesses!

Posted by Mikko Luukinen

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