Mood disorders cover a large spectrum of disorders with the most prominent being major depression (MDD) and bipolar disorder (BD) [1]. However, in the past 20 years, there remains a lack of significant advances in treatment; Prozac, which was a popular antidepressant in the 1980’s, continues to currently trump as one of the most prescribed drugs for depressive patients [1]. In fact, medications like Prozac along with cognitive behavioural therapy (CBT) have been shown across many NICE (National Institute for Health and Care Excellence) studies as the most effective way to treat depressive individuals [1]. Other commonly prescribed drugs include selective serotonin reuptake inhibitors (SSRIs) such as sertraline, citalopram, and asenapine. SSRIs block the reuptake of serotonin, allowing serotonin to more freely pass messages to nearby brain cells [2]. A surplus of serotonin helps to better regulate mood, feelings and sleep. If the patient experiences other health issues alongside depression, such as those chronic pain, serotonin-norepinephrine reuptake inhibitors (SNRIs) are prescribed instead which elevate both serotonin and norepinephrine in the brain to alter the brain's neural circuitry and better regulate mood [2]. In terms of therapy, cognitive behavioural therapy (CBT) is the most common therapy for individuals with depression as it has been proven to improve symptoms in the least amount of time [3]. Patients with depression often have stressful life events, interpersonal conflicts, and personality issues largely due to negative, distorted thoughts. CBT aims to correct this by reducing the times people overgeneralize negative thoughts from one event [3]. When more accurate thoughts are introduced by a psychotherapist, it has been shown to have a positive effect on depression. Psychoeducation is commonly prescribed as well where patients, along with their family members, are encouraged to work through informational material in order to discover more about the illness. In doing so they are more informed and willing to work together with health professionals, which is important, as making a plan for treatment with a professional can help reduce relapse and help the individual stick with the treatment protocol they are given [3]. Typically, treatment plans are followed until the 4-week mark, after which, if the treatment doesn't work, medication is administered at a higher dosage, or an entirely different drug is used [2]. Lithium, psychostimulants, and modafinil are used to increase the sedative effect, however, if an individual experiences psychosis while in a depressive mood, then hospital treatment is recommended, where psychiatric treatment can help with manic or depressive disorders [2]. The other most common mood disorder is bipolar disorder. The first line of treatment for BD are mood stabilizers such as lithium salts, followed by anticonvulsants like valproate and carbamazepine [4]. Lithium salts are thought to be the best at preventing bipolar disorder as the high concentrations of lithium are known to strengthen nerve cell connectors in brain regions involved in regulating behaviours and mood [4]. Anticonvulsants on the other hand are a secondary option, but still provide a strong sedative effect known to help with calming hyperactivity [5]. Aripiprazole, olanzapine, and risperidone, are a class of atypical antipsychotics that have also been shown to have antimanic properties, however, they are normally prescribed in tandem with other anti-manic drugs (ex. antipsychotics, mood stabilizers, etc...) due to the fact that not enough research has been done to confirm their effectiveness [5]. While taking medication, many doctors advise patients to go through many types of psychotherapy [6]. Once again, psychotherapy is beneficial, helping to improve relationships, increase problem-solving ability, and help the patient control his/her behaviours [6]. Electroconvulsive therapy (ECT), where small electric charges are passed through the brain while the patient remains under general anaesthesia, is sometimes administered in cases of medication-resistant major depression [7]. It is unknown the exact mechanism through which ECT provides relief from depression symptoms, however, experiencing negative symptoms such as memory loss and confusion are seen in rare circumstances [7].
When brainstorming possible projects for the year, our team became very interested in the gut-brain axis (elaborated further in the next section) and its relationship to mood disorders. Though there are several important mood disorders, we decided to focus on MDD as there was a strong correlation to the gut-brain axis. Thus, we began looking into possible gaps in treatment to address, however, we discovered that while there was a need to surpass and better current treatment methods, there was an even bigger need in the diagnosis process. Currently, diagnosis for MDD includes the DSM-5 Diagnostic Criteria which involves the following. Patients must have a minimum 5 symptoms for a two week period. Those may include depressed mood, diminished interests, suicidal thoughts and fatigue [8]. Additionally, there must be impairment in social relationships, at the workplace and in other important areas. The person also must not have had a manic or hypomanic episode [8]. It is noted to physicians however that sometimes people may experience extreme sadness due to bereavement or financial loss, which may resemble a depressive episode (and thus satisfy the above criteria) [8]. Depressive episodes must include feelings of worthlessness, inability to feel pleasure, and persistent ruminations that are pessimistic in nature [8]. Healthcare professionals use the DSM to evaluate the symptoms and decide which type of depression you may have. Symptoms are evaluated according to a diagnostic code. Depression ranges from being mild to severe, and can have psychotic symptoms. People can have relapsed episodes of depression or can be in a state of remission (not fully recovered) [8]. However, there is an overwhelming amount of literature that details individual-to-individual variability within the disorder. Precision medicine is a hot topic that has emerged in recent years. Instead of taking a statistical average and prescribing a one-size-fits-all dose of medication, precision medicine allows us to create individualised drugs and treatment plans that are tailored to the patient's unique genetic makeup [9]. This includes collecting data on the person's genes, phenotype, and proteins in the body [9]. It is currently used in oncology, where information about a tumour is used to create an individualised diagnosis, treatment plans and prognosis [10]. Benefits of precision medicine is that it is able to determine the onset of the disease before it happens, enables more effective drugs to be prescribed to the patient, predict the course of disease progression, and reduce cost, time and failure rate of clinical trials in research [11]. Therefore, a group of individuals might be similarly diagnosed with MDD, however, progression along the disorder may differ from individual to individual, and therefore they should not all necessarily be prescribed the same medication. Likewise, each individual may be at a higher or lower risk for MDD; thus, we decided to focus on creating a system that might be able to non-invasively and easily assess the risk of an individual for MDD.