Probiotic Supplementation and Major Depressive Disorder
Faculty Advisor Name
Abby Masssey
Department
Department of Health Professions
Description
Depression is a term that can both represent a transient emotional state as well as a clinical condition.1 Unipolar major depression is a very common condition with estimated lifetime prevalence of about 21% in the United States.1 In a study of over 36,000 adults in the US, the average age of onset of a first episode of major depression occurs at 29 years old.1 Diagnosing depression in adults requires the near daily presence of at least five of the following nine symptoms which include: depressed mood most of the day, little interest in doing things most of the day, insomnia or hypersomnia, significant weight loss or gain or appetite changes, psychomotor retardation or agitation that is noticed by others, fatigue or low energy, decreased ability to concentrate or make decisions, excessive or inappropriate thoughts of worthlessness or guilt, recurrent thoughts of death, suicidal ideation or attempt.2
Probiotics are living microorganisms and when taken in adequate amounts, interact with host microbiota to suppress pathogens exposed to the human body.3 Probiotics often contain microorganisms such as bacteria including Lactobacillus and Bifidobacterium and yeasts such as Saccharomyces boulardii (NIH).4 Probiotics work in a variety of ways, including helping to maintain the health of the microbiome, produce beneficial substances, and help the immune system (NIH).4 Gut microbes play a large role in many psychiatric disorders as there is a bidirectional communication between the brain and gut called the microbiota-gut-brain axis (MGBA).3
Many studies have shown that bacteria are important for many different physiological processes and transmit and interpret information from the periphery of the body back to the brain and vice versa.3 It involves neural pathways such as the vagus nerve and enteric nervous system along with cytokine and endocrine pathways all of which are found to be altered in psychiatric disorders.3 Once the microbiome senses stress, it influences the hypothalamic pituitary axis to release cortisol.3 Therefore, stress induced cortisol can be altered by taking probiotics.3
While antidepressants may work for some people, there are others who say they have no effect on them with the effect of antidepressants being around 40-60%.5 With the many different types of antidepressants available, there are also many side effects such as dry mouth, headache, dizziness, and sexual dysfunction.5 It was found that there is a significant difference in the gut microbiota composition in those with depression and individuals without clinically diagnosed depression.3 The aim of this literature review is to assess whether probiotic supplementation can improve clinical symptoms of depression in adults.
Probiotic Supplementation and Major Depressive Disorder
Depression is a term that can both represent a transient emotional state as well as a clinical condition.1 Unipolar major depression is a very common condition with estimated lifetime prevalence of about 21% in the United States.1 In a study of over 36,000 adults in the US, the average age of onset of a first episode of major depression occurs at 29 years old.1 Diagnosing depression in adults requires the near daily presence of at least five of the following nine symptoms which include: depressed mood most of the day, little interest in doing things most of the day, insomnia or hypersomnia, significant weight loss or gain or appetite changes, psychomotor retardation or agitation that is noticed by others, fatigue or low energy, decreased ability to concentrate or make decisions, excessive or inappropriate thoughts of worthlessness or guilt, recurrent thoughts of death, suicidal ideation or attempt.2
Probiotics are living microorganisms and when taken in adequate amounts, interact with host microbiota to suppress pathogens exposed to the human body.3 Probiotics often contain microorganisms such as bacteria including Lactobacillus and Bifidobacterium and yeasts such as Saccharomyces boulardii (NIH).4 Probiotics work in a variety of ways, including helping to maintain the health of the microbiome, produce beneficial substances, and help the immune system (NIH).4 Gut microbes play a large role in many psychiatric disorders as there is a bidirectional communication between the brain and gut called the microbiota-gut-brain axis (MGBA).3
Many studies have shown that bacteria are important for many different physiological processes and transmit and interpret information from the periphery of the body back to the brain and vice versa.3 It involves neural pathways such as the vagus nerve and enteric nervous system along with cytokine and endocrine pathways all of which are found to be altered in psychiatric disorders.3 Once the microbiome senses stress, it influences the hypothalamic pituitary axis to release cortisol.3 Therefore, stress induced cortisol can be altered by taking probiotics.3
While antidepressants may work for some people, there are others who say they have no effect on them with the effect of antidepressants being around 40-60%.5 With the many different types of antidepressants available, there are also many side effects such as dry mouth, headache, dizziness, and sexual dysfunction.5 It was found that there is a significant difference in the gut microbiota composition in those with depression and individuals without clinically diagnosed depression.3 The aim of this literature review is to assess whether probiotic supplementation can improve clinical symptoms of depression in adults.
