Research Paper Example on Family History of Depression

What is MDD:

MDD (Major depressive disorder) or depression, is an incredibly common mental illness that affects hundreds of thousands of people, but what does it mean to be depressed? The APA (American Psychiatric Association) defines depression as “a common and serious medical illness that negatively affects how you feel, the way you think and how you act”.

Cognitive deficits in MDD:

Depression or Major Depressive Disorder (MDD) is distinguished by disabilities related to mood, enthusiasm, as well as cognition. It is also often linked to considerable major drops in quality of life and psychosocial functioning (frontier). A large portion of MDD patients who succeed in symptomatic remission, which means (a considerable reduction symptom inetnsity), do not come back to function in the same way they used to in their pre-MDD days. That leads to them being significantly less efficient in the workplace and less productive, further worsening the economic burden caused by MDD. The Accumulated yearly loss of that is over Fourty Billion in all of North America.

Out of all areas of losses in human capital, cognition takes the biggest hit. which negatively effects different aspects of the person’s life like global function, workplace productivity/performance and quality of life. According to ( Zuckerman H, et al): “Clinically, cognition has been classified into four subdomains: 1- learning and memory. 2- attention and concentration. 3- executive function. 4- processing speed. MDD patients commonly present with impairments in each of the sub-domains of cognition”. To expand: ( Zuckerman H, et al) adds “ Cognition is a non-pecific term that refers to mental processes associated with thinking, learning and memory. Cognitive dysfunction can be defined as a transological domain serving an essential mediator of disparate mental disorder ”

2 theories regarding this:

There are two main theories to explain the cognitive impairments in individuals with MDD.

The first theory to explain this phenomenon is the cognitive reserve hypothesis, which imposes: Lower IQ in the early years of a person’s life surges the likelihood of the person developing a mental illness during adulthood. A study was conducted to test this hypothesis, recording the IQ of New Zealand citizens over the period of 20 years. The study (Karestan C, et al) reports “lower childhood IQ was associated with greater comorbidity and with persistence of depression”. In summary, this study concluded that MDD patients are predisposed to cognitive deficits.

The second theory is the scarring hypothesis which imposes: MDD results in determined intellectual shortages after the illness has taken root, a study has been conducted by (Moraros. J et al), they conducted a methodical search of scholarly, peer-reviewed articles from different sources . Specifically 5 random articles out of over four thousand articles. They concluded “Use of antidepressants was associated with significant twofold increase in the odds of some from of cognitive impairment”

OBJECTIVE + METHODS:-

One way to answer this would be to study the unaffected relatives. As relatives share 50% of the MDD related genes. This study (Lynn E et al) is the first of it’s type, according to authors. This study wants to clarify the origin of cognitive impairment of people with MDD. Previous studies potentially lacked sample sizes or statistical power, this study is different in that regards and wishes to investigate the difference between direct family members with controls and test a wide range of cognitive domains.

A group of researchers looked at the direct relatives, (meaning their sibling, parents or children) of people with MDD that don’t actually suffer from MDD, since direct relatives share about half of the genes that are related to depression. This would determine whether cognitive impairment in MDD patients is because of the genes, or if it’s a product of their lifetime journey with it and the medication they take.

The study wanted to answer a simple question, “Is cognitive impairment present in relatives of people with MDD”, to answer that question, the authors conducted an analysis which observed more than 54 studies which testes more than 8000 people between direct family members of MDD patients and a control group that has not been diagnosed (nor has a family history of) Bipolar, Schizophrenia, or MDD, via a trusted diagnostic instrument. The study also wanted eliminate the factor of cognitive decline associated with aging, and therefore excluded all participants 70 years and older.

Results, unaffected relatives vs controls

Conducting a test over all the cognitive subdomains between people with Family history of MDD and controls, results indicate that the relatives of MDD patients have significantly impaired cognition, one other explanation for this other than the aforementioned theories, is genetic and social factors, recent studies have found that there is a link between the genes responsible for MDD and many loci in genes. For example, NEEGR1 (Nueronal Growth Regulator 1 Gene) has a strong connection to MDD, it plays important roles in important parts of the brain responsible for memory and other mental tasks.

One other external factor that could contribute to Cognitive deficits in people with family history of MDD is their environment, if they grow up struggling with money, or their social status (no education or decent job), they could be adversely affected even if they do not develop MDD. Furthermore, previous research indicates that mothers with MDD don’t pay as much attention and didn’t talk to their toddlers as often, also that the kids of these mothers don’t talks as much in comparison with controls, all of this might affect cognition in these children. All that being said, the authors state: “a genetic mechanism is a more likely determinant of cognitive deficits in unaffected relatives”. This is after they have conducted an analyses where they isolated these factors.

Early intervention

In an effort to take action following this study, the authors state: “These finding might lead to implicate an early intervention in people with family history of MDD, they could aim to mediate the effects of depression”. Further adding “intervention focusing on cognitive performance with children of MDD-diagnosed mother, has benefits in both child cognition and maternal health”. Concluding with “such intervention have been shown to protect children’s cognitive development”

Sources:

1- Cognitive Performance in First-Degree Relatives of Individuals With vs Without Major Depressive Disorder A Meta-analysis.

Lynn E. MacKenzie, MA; Rudolf Uher,MD, PhD; Barbara Pavlova, PhD, DClinPsy

2- Zuckerman H, Pan Z, Park C, Brietzke E, Musial N, Shariq AS,Iacobucci M, Yim SJ, Lui LMW, Rong C and McIntyre RS (2018)Recognition and Treatment of Cognitive Dysfunction in Major Depressive Disorder.Front. Psychiatry 9:655.doi: 10.3389/fpsyt.2018.00655

3- Childhood IQ and Adult Mental Disorders: A Test of the Cognitive Reserve Hypothesis Karestan C. Koenen, Ph.D.et al

4- Cognitive impairment in major depressive disorder. Zihang Pan et al.