Overcoming Depression at the Level of the Brain

Depression is a common but serious mood disorder that causes persistent feelings of sadness. Many people, ranging from young to old, suffer from depression. It is especially prevalent in young adults and college students. Those suffering from depression often have trouble doing every day activities and sometimes may feel that life is hopeless.

However, since depression has been around for so long and is so common, the good news is there are numerous treatments for it that have been proven successful. Two of the most common treatments are antidepressant medication (SSRIs) and cognitive-behavioral therapy. Here, we take a closer look at how these two treatments work in battling depression at the level of the brain.

Levels of serotonergic neurotransmission play an important role in determining mood. Depression is said to caused by low levels of serotonergic neurotransmission. SSRIs counter these low levels by interfering with the serotonin transporter 5-HTT—it causes slower reuptake of serotonin. This causes the low levels of serotonin in the brain to be elevated, thus relieving depression. Like antidepressant medication, cognitive-behavioral therapy also produces changes in the brain when treating depression. In those suffering from depression, their hippocampus decreases in size by the constant release of glucocorticoids due to stress. This, in turn, creates more stress and depression. It has been found that after completing CBT, those with depression show significant improvement in their depression, which is associated with significant increases in the hippocampus. Both antidepressant medication and CBT are successful in treating depression, however how they affect the brain in different ways to achieve this.

Those who struggle with depression also face risk of relapse after discontinuing treatment. In terms of preventing relapse, it has been shown that CBT has significantly less risk of relapse than medication. In one study, it was found that the percent of relapse after treatment was 30% for CBT versus 76% for antidepressant medication. A reason for this disparity may be that CBT teaches patients how to change the way they think and in turn, how they feel and act, so that even after they discontinue therapy, they can continue to apply the skills they have learned in therapy. Medication only changes the serotonin levels in the brain with no conscious effort on the person’s part, so it is harder to prevent depression after discontinuing the medication.

In conclusion, both antidepressant medication and cognitive-behavioral therapy relieve depression by altering the brain. Medication works by inhibiting serotonin reuptake, which elevates the low levels of serotonin in people with depression. CBT helps patients change the way they perceive thoughts, which has been associated with increased hippocampus size, which helps prevent stress and depression. However, when discontinuing treatment, those who completed CBT are at a much lower risk of relapse than those who took medication, as CBT teaches people skills they can apply even after treatment ends. It is often recommended to those suffering from depression a combination of medication and therapy, so that they have the most promising outlook on overcoming their depression.

 

Goldapple, K. (2004, January 01). Modulation of Cortical-Limbic Pathways in Major Depression. Retrieved January 16, 2019, from https://jamanetwork.com/journals/jamapsychiatry/fullarticle/481941
Hollon, S. D. (2005, April 01). Prevention of Relapse Following Cognitive Therapy vs Medications in Moderate to Severe Depression. Retrieved January 16, 2019, from https://jamanetwork.com/journals/jamapsychiatry/fullarticle/208447
Schafer, W. R. (n.d.). How Do Antidepressants Work? Prospects for Genetic … Retrieved January 16, 2019, from https://www.cell.com/cell/fulltext/S0092-8674(00)80042-2

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  Timothy Durham was convicted of rape when a test showed his DNA genotype matched the DNA recovered from the crime scene. Eye witnesses testified that Durham was in a different state at the time of the incident, but he wasn’t exonerated from his 3000 year sentence until follow up DNA analysis showed that the preliminary forensic analysis used in the trial was misinterpreted (Thomas et al.). DNA testing serves an invaluable part in our criminal justice system, but it comes with complications and bias that can lead to wrongful convictions and misinformed juries.  

Background:

Forensic genetics aims to identify the origin of a biological sample. It can be traced back to Karl Landsteiner who discovered human ABO blood groups. With blood groups, suspects could be eliminated based on their blood type. For example, if a suspect had type A blood and there was type B blood left at the scene by the perpetrator, the investigators could rule out the suspect. Unfortunately, the reverse didn’t work. If the suspect and perpetrator both had the same blood type, it can’t be concluded that the suspect was guilty. Blood identifiers evolved into 8 distinct categories which improved the ability to eliminate suspects, but could only conclude that (if the system matched) it might be the perpetrator or this person might be related to the perpetrator (Jobling and Gill). The field evolved in the 1980s with the discovery of Minisatellites, lines of repetitive DNA that don’t encode proteins. Minisatellite patterns in DNA create what we know today as the DNA fingerprint, and it has a much higher accuracy rate than previous methods (Augustyn et al.). Around the same time, a breakthrough for victims of sexual assault was discovered. In the case of assault, bodily fluids of both the victim and the assaulter can get mixed. A process called differential lysis was created which could selectively increase the concentration of sperm in a fluid sample thereby allowing for accurate DNA testing (Jobling and Gill). Forensics evolved to use single-locus probe testing after several years because of its ease of interpretation. It looked at specific minisatellites that had high variability between subjects. This was the first DNA-based method to be used in a criminal investigation. Two murder homicides from several years apart were connected using DNA evidence. The evidence was then used to exonerate an innocent man, and the guilty party was found when he tried to evade mandatory DNA testing for all men in the small town. His guilt was then reinforced when the DNA profiles matched, and he gave a confession (Jobling and Gill). Finding DNA at a crime scene doesn’t guarantee that you’ll find a murderer. There are issues with non-pure samples and limited samples that make DNA work difficult, and accreditation of facilities and new techniques and take time (Jobling and Gill).  

Subjectivity of DNA Interpretation:

In a 2009 publication, the National Academy of Science discusses the possibility for subjective influence in lab based forensics. The interpretation bias happens in complex cases where, for example, there could be a mixture of DNA. A study published in 2011 looked specifically at this issue. A gang rape happened in Georgia, and the mixture in DNA from the case was used to prosecute one suspect after another suspect took a plea bargain to testify against him. With DNA mixtures, there are three possible conclusions: suspect excluded, suspect cannot be excluded, and inconclusive. If the suspect is excluded, it means that there’s little to no possibility that his DNA is part of the sample. If the suspect cannot be excluded, it means that there’s a possibility that his DNA is part of the sample. In the trial, the DNA examiners who knew the context of the case concluded that the suspect being prosecuted could not be excluded. The 2011 study gave the DNA evidence from this case and the DNA profiles of the suspects to 17 forensic examiners. These examiners had no context of the case, and they all worked independently. Of the 17, only 1 came to the same conclusion (suspect cannot be excluded) as the examiners who knew the context of the case. Twelve of the 17 concluded that the suspect who was prosecuted and convicted had no relation to the DNA found in the sample. Not only does this show that subjectivity occurs due to the context of the case, but the 17 examiners came up with different findings based on their past experiences meaning that not all DNA analysis is objective. Some organizations like the Scientific Working Group on DNA Analysis Methods say that quantitative statistical evidence should be presented with every categorical conclusion, but the US doesn’t require this (Dror and Hampikian).

False Positives:

There are two categories that cause wrongful identification in a DNA report: coincidental matches and false positives. Coincidental matches are DNA matches between two unrelated people. The probability of these matches is about 1 to 500,000 for white individuals and about 1 to 350,000 for black individuals. This small probability of coincidental matches makes people feel confident in DNA evidence. False positives, on the other hand, are matches between DNA and test DNA that result from issues in the forensics lab. There have been multiple cases of forensics labs accidentally switching victim and suspected rapist DNA which lead to convictions that were later overturned when the lab realized the error. There are also cases of misreading or misunderstanding a sample. In a case from 1993, a man was convicted of rape because someone interpreted a mixed sample of victim and perpetrator DNA as an individual sample. The conviction was again overturned. To prevent false convictions, retesting DNA is allowed, but it’s not an efficient solution. Many people are pushing for statistical information on the probability of false positives, so that the jurors can make accurate judgements based on DNA evidence (Thomas et al.).  

Conclusion:

DNA analysis is a useful tool for the criminal justice system, but subjectivity can be an issue in forensic testing. To combat wrongful convictions, there are organizations like The Innocence Project who use DNA testing to free the innocent, but reformed forensic testing standards should be put in place to prevent subjectivity and to ensure juries are correctly informed during trials. https://www.innocenceproject.org/    

Citation:

Augustyn , Adam, et al. “DNA Finerprinting.” Encyclopedia Britannica , 26 Apr. 2018, www.britannica.com/science/DNA-fingerprinting#ref153186. Dror, Itiel E., and Greg Hampikian. “Subjectivity and Bias in Forensic DNA Mixture Interpretation.” Science & Justice, vol. 51, no. 4, 2011, pp. 204–208., doi:10.1016/j.scijus.2011.08.004. Jobling, Mark A., and Peter Gill. “Encoded Evidence: DNA in Forensic Analysis.” Nature Reviews: Genetics, vol. 5, no. 10, Oct. 2004, pp. 739–751., doi:10.1038/nrg1455. Thompson, William C, et al. “How the Probability of a False Positive Affects the Value of DNA Evidence.” Journal of Forensic Sciences, vol. 48, no. 1, Jan. 2003, pp. 1–8., doi:10.1520/jfs2001171.