Could depression be a form of adaptation?

The most recent theory on depression is that it could be some type of adaptation. I have written regarding this idea before in a post titled Evolutionary origins of the depression epidemic. The author of the book in that previous post was making a similar argument. He believed that depression was not a pathological condition but a way of adapting to stressful conditions. For example if a person lost a job and became depressed the depression could perhaps be a way of conserving energy or the depression might be suggesting that a person should change their goals.

In that previous post I wrote that depression in its milder forms could conceivably be seen as an adaptation however in its more severe forms not very likely. After all severely depressed people have problems functioning on a very basic level and aren't analyzing problems in the most objective or productive manner. Often depression seems to reduce flexibility and brainstorming. The only solution for many severely depressed people is suicide. It is more accurate to say that majorly depressed people obsess more than they analyze.

I, for example, have experienced chronic depression for most of my life and while being rather obsessive and analytical still have not gained  much insight into why I have felt depressed for most of my life. I have experienced many periods where I felt normal and quite productive but it wasn't necessarily due to some kind of insight. Those normal periods just happened and sometimes they occurred in a diurnal pattern or in a menstrual pattern which makes no sense in regard to the theory. Why would one person feel severely depressed in the morning and normal at night for a number of days? Why would I often feel normal to euphoric when I had my period? Various levels in hormones and their effect on neurotransmitters seem more likely.

This most recent research is suggesting the adaptation theory once again only instead of conserving energy depression focuses our energy obsessively on one thing and supposedly solves it.

The research suggests that depression may be a natural condition in which the mind concentrates involuntarily on a complex issue to the point where it allocates resources to analyzing the problem at hand, diminishing concentration on other aspects of living, perhaps giving rise to disrupted eating, sleeping and social interaction that are associated with depression.

This theory seems to assume the idea that depression is due to excessive stress which is debatable. One can feel more stressed pursuing a goal and yet have a reduced level of depression.  For example, I have given up on a number of goals which I found stressful and have not noticed any positive change in my level of depression. In fact, I felt worse for giving up on my goal. A proponent of this theory might also argue that I haven't made the right changes in my life. How does one falsify this theory if this is their answer. Additionally, the proponents of this theory keep pointing out that there is no conclusive evidence of pathology in major depression. True but it doesn't necessarily follow that pathology won't be discovered in the future. The fact that depression increases the likelihood of dementia is sufficient reason to keep looking for pathology in regards to depression.

CBT: a questionable form of therapy for depression

CBT is a therapy based on the belief that one's negative illogical thoughts can cause depression and correcting them can treat the depression. CBT therapy is usually performed with a therapist however now computer programs are being created to help depressed individuals. While CBT therapy is endorsed by psychiatry it has a number of problems.

Depression is known to cause distorted thinking so what comes first the depression or the distorted thinking? CBT doesn't clarify this issue. It just says that correcting illogical thinking treats the disorder.

CBT therapy has been shown to be as effective as antidepressant therapy and prevents relapses better than drugs. The problem with this is that antidepressant therapy isn't all that effective. Antidepressants are, in reality, only slightly more effective than a placebo. Additionally, since major depression is cyclical how does one know for sure if the treatment was actually helping. Many experiments are performed over rather short periods of time and a certain percentage of people will have spontaneous remissions. This of course could be the same issue for antidepressant trials.

Experiments involving CBT vs antidepressants are not double blind which is considered essential for the highest level of objectivity. If the researchers and the patients know what type of therapy is being performed objectivity is diminished.

A major criticism has been that clinical studies of CBT efficacy (or any psychotherapy) are not double-blind (i.e., neither subjects nor therapists in psychotherapy studies are blind to the type of treatment). They may be single-blinded, i.e. the rater may not know the treatment the patient received, but neither the patients nor the therapists are blinded to the type of therapy given (two out of three of the persons involved in the trial, i.e., all of the persons involved in the treatment, are unblinded). The patient is an active participant in correcting negative distorted thoughts, thus quite aware of the treatment group they are in

Researchers say that brain scans show that CBT "works" and yet brain scans are not considered a reliable way to diagnose mental illness. People with mental illness often have more than problem such as depression and ADD. This confounds diagnosing a mental disorder or saying confidently that an individual is in remission. This excerpt from Scientific American explains the problem.

During testing, the system analyzed the shapes of brain regions in each test scan and assigned it to the group it most resembled. The scientists checked its work by comparing the new labels on the test scans with the original clinical diagnoses. They repeated the procedure several times with different randomly generated sets. When the system chose between two disorders or one ailment and a clean bill of health, its accuracy was nearly perfect. When deciding among three alternatives, it did much worse.

The basis of CBT doesn't explain how people with a rapid cycling form of bipolar disorder cycle between depression and mania. Do they start off having negative thoughts during a depressive episode which eventually cycles with mania  and the mania consequently produces delusional thinking? CBT has not been shown to be effective for preventing depressive episodes in bipolar disorder.

CBT has given no biological explanation for how it works and yet implies that possibly negative thoughts might exacerbate stress which in turn precipitates a depressive episode. Even though stress has long been thought to cause depression stress(HPA activation) is not distinctive to just depression. Stress is implicated in numerous health problems in a rather vague manner. To further complicated matters what is stressful to one person isn't stressful to another. Consequently it is complicated to study stress.

In the end CBT emphasizes that depressed people are responsible for their depression which is still questionable in the eyes of science.

Fish intake might improve antidepressant response

Approximately half of the people suffering with depression don't respond to SSRIs. Recently a group of Dutch researchers discovered that adding fish oil to antidepressants increases the response rate.

According to a lead researcher they saw that depressed patients had an altered metabolism of fatty acids, and this altered metabolism was affected by stress hormones. In the experiment the researchers planned on examining the relationship between depression and fatty acids, and hormones such as cortisol.

They took 70 patients with depression and compared them to 51 healthy controls, by measuring their fatty acid levels and cortisol levels. They then gave the depressed patients 20mg of an SSRI daily for 6 weeks, and in those who did not respond to the SSRIs the dose was gradually increased up to 50mg/day. Fatty acid and cortisol levels were measured during the trial.
They found that the MDD patients who didn't respond to the SSRI also tended to have abnormal fatty acid metabolism, so they checked the dietary habits of all those taking part in the trial. Fatty fish is rich in fatty acids, such as the well-known Omega-3 DHA. So the researchers looked at the amount of fatty fish in the diet of all involved in the trial. They categorised the patients into 4 groups, according to their fatty fish intake, and they found that those who took the least fish tended to respond badly to anti-depressants, whereas those who had most fish in the diet responded best to anti-depressants. Those who ate fatty fish at least once a week had a 75% chance of responding to antidepressants, whereas those who never ate fatty fish had only a 23% chance of responding to antidepressants.

There were a couple of problems with this study. For one thing the study was on the small side and should be replicated with a larger one. A second problem is that the researchers appeared to know the fatty acid status of the depressed patients so they might have subconsciously altered the depression scores in order for their hypothesis to be proven correct. How the depression scores were measured is unclear from the article.

Andrew Stoll was one the first researchers to notice the antidepressant effect of fish oil. He theorized that fish oil might effect the composition of nerve cell membranes and consequently neurotransmission. Barry Sears, author of " The Zone", was another researcher who mentioned that stress could effect the type of fatty acids. They both probably inspired this study. I did not read the original article so if you are curious you will have to pay for the article through ECNP.

One way exercise could act as an antidepressant

Researchers have recently discovered that there is an enzyme in muscle that detoxifies a substance which tends to be high in the mentally ill. The substance Kynurenine is produced when an individual is exposed to stress. Exercise has long been considered as an antidepressant with stress reducing properties. This could perhaps be one explanation and a new way to target depression.

The researchers discovered that mice with higher levels of PGC-1a1 in muscle also had higher levels of enzymes called KAT. KATs convert a substance formed during stress (kynurenine) into kynurenic acid, a substance that is not able to pass from the blood to the brain. The exact function of kynurenine is not known, but high levels of kynurenine can be measured in patients with mental illness. In this study, the researchers demonstrated that when normal mice were given kynurenine, they displayed depressive behaviour, while mice with increased levels of PGC-1a1 in muscle were not affected. In fact, these animals never show elevated kynurenine levels in their blood since the KAT enzymes in their well-trained muscles quickly convert it to kynurenic acid, resulting in a protective mechanism.

In comparison to medication I have received more benefits from exercise with respect to stress reduction. Many antidepressants can also reduce stress however they have side effects, one of which is sedation with a loss of motivation.