Mood changes may be a constitutive feature of several psychiatric disorders and a broad classification based on the nature of the disorder (sadness or elation) can be made into depressive and manic mood changes, each presenting with distinct clinical features [1] [2]:

• Depressive disorders - Numerous subtypes have been described in literature - major depressive disorder, persistent depressive disorder, substance or medication induced, depression occurring as a result of another disease, premenstrual dysphoric disorder and unspecified forms [3] [4]. The presence of irritable or sad mood that substantially influences everyday life of affected individuals due to somatic and cognitive disturbances is a common finding in all of them, but their distinction can be made according to the duration, onset or the underlying etiology [2]. For example, major depressive disorder is diagnosed when mood changes last for at least two weeks, while persistent depression is suspected if symptoms last for two years in adults and one year in children [2]. Moreover, patients may suffer from psychotic, melancholic or catatonic episodes that can mislead the physician from depression as the underlying disorder.
• Mania and hypomania - Abnormally irritable and expansive mood present for one week accompanied by symptoms such as elevated self-esteem, decreased need for sleep, psychomotor agitation, racing thoughts, increased goal-directed activity and a propensity for distraction by irrelevant or unimportant stimuli are hallmarks of a manic episode [2] [5]. A fast rate of speech, verbosity, accelerated mental and physical activity, and personal belief that he/she is at an excellent mental state is often encountered, which can be dangerous or even life-threatening. A hypomanic state is described as a milder form of mania, lasting at least four days and presenting with less severe clinical symptoms than that observed in manic patients [5].
• Bipolar disorders - When manic episodes, depression, and/or hypomania are all seen in one individual, the diagnosis of a bipolar disorder should be suspected. Like in depressive disorders, several clinical types are recognized - type I, type II, drug-induced, etc. [1], while cyclothymia denotes a less severe form.

• Family History of Depression

  It is not clear whether people who have had depression before, or have a family history of depression, are more prone to this complication, and its causes are not understood. [benzo.org.uk]

  However, it can also occur in people who have no family history of depression. [0005] Major depressive disorder is prevalent in a large number of elderly patients, resulting in a significant increase in the number of suicides in this population. [faqs.org]

• Hypoxemia

  Abstract Hypoxemia is a common complication of the diseases associated with the central nervous system, and neurons are highly sensitive to the availability of oxygen. [ncbi.nlm.nih.gov]

• Gaucher Disease

  Gaucher disease (GD) is a lysosomal storage disorder with a wide spectrum of phenotypic presentations. We report the case histories of two adult brothers with GD who developed both parkinsonism and psychiatric symptoms. [ncbi.nlm.nih.gov]

• Feeling of Worthlessness

  Affective disorders may include manic (elevated, expansive, or irritable mood with hyperactivity, pressured speech, and inflated self-esteem) or depressive (dejected mood with disinterest in life, sleep disturbance, agitation, and feelings of worthlessness [britannica.com]

  Other symptoms of depression may include: changes in appetite, sleep disturbances, low energy, difficulty thinking or concentrating, feelings of worthlessness and guilt, anxiety and thoughts of suicide. [newmarkeducation.com]

  […] of worthlessness or guilt Difficulty concentrating Recurrent thoughts about suicide Major depressive disorder is much more common in women than in men. [sparknotes.com]

  Symptoms, that are persistent and interfere with daily life, can include: Sadness or loss of interest or pleasure in activities the person used to enjoy Weight loss Difficulty sleeping or oversleeping Energy loss Feelings of worthlessness Thoughts of [wexnermedical.osu.edu]

• Suicidal Ideation

  OBJECTIVE: To examine the associations between personality traits and suicidal ideation (SI) and attempt (SA) in mood disorder patients and community controls. [ncbi.nlm.nih.gov]

  In severe cases depression can lead to suicidal ideation or psychosis. [youtube.com]

• Euphoria

  The presence of mania (p 0.033) or euphoria/elevated mood (p 0.041) were the pretreatment symptoms significantly associated with an "improved" rating. [ncbi.nlm.nih.gov]

  Depression is the more common symptom, and many patients never develop a genuine manic phase, although they may experience a brief period of overoptimism and mild euphoria while recovering from a depression. [britannica.com]

  Bipolar disorder also can cause elevated moods (mania) that are accompanied by feelings of euphoria, grandiosity, extreme energy and heightened arousal. [chihealth.com]

  […] worthless, guilty, or constant self-criticism Unable to concentrate or focus Irritable and easily frustrated Trouble sleeping or oversleeping Bipolar disorder Bipolar disorder causes extreme mood swings ranging from mania or extreme happiness, grandiosity, euphoria [bhevolution.org]

  During mania, notes The Harvard Mental Health Letter, bipolar patients “can be unbearably intrusive and domineering, and their reckless and restless euphoria may suddenly change into irritability or rage.” [wol.jw.org]

• Low Self-Esteem

  Dysthymic disorder can be characterized as a chronic low-grade depression, persistent irritability, and a state of demoralization, often with low self-esteem. [healthychildren.org]

  Bipolar Disorder can manifest in many ways, including: difficulty falling or staying asleep, difficulty waking up in the morning, chronic fatigue, anxiety, low self-esteem, high irritability and risky or destructive behaviors. [newmarkeducation.com]

  These mood disorders share some common symptoms: Slowness in motor behavior/speech Slowed thought processes Blunted emotions Poor grooming Social withdrawal Weight loss/gain Early morning awakening Excessive sleeping Low self-esteem Agitation In addition [bhevolution.org]

  In contrast, during an episode of depression, a person can suffer from feelings of worthlessness, loss of interest, low self-esteem, and lack of energy. [pamf.org]

  Symptoms may include: Persistent feelings of sadness, hopeless or helpless Having low self-esteem Excessive guilt Feelings of wanting to die Suicidal thoughts or attempts Loss of interest in usual activities or activities once enjoyed Difficulty with [texaspanhandlecenters.org]

• Suicidal Depression

  Depression may be linked to a variety of causes, including genetic, environmental, psychological and biochemical factors. [wexnermedical.osu.edu]

  The most dangerous consequence of severe depression is suicide. Depression is a much more common illness than mania, and there are indeed many sufferers from depression who have never experienced mania. [britannica.com]

  depressive patients. 61 54 Gos T...Bogerts B 18574609 2008 45 BDNF gene: functional Val66Met polymorphism in mood disorders and schizophrenia. 54 61 Rybakowski JK 19018714 2008 46 The tryptophan hydroxylase gene influences risk for bipolar disorder but [malacards.org]

  Depression can dramatically impair a person’s ability to function both in social situations and at work. [disability-benefits-help.org]

• Organic Psychosis

  The best described neuropsychiatric alterations are dementia and an organic psychosis. Organic mood disorder has been reported less often, and mania secondary to idiopathic basal ganglia calcification has not been noted previously. [ncbi.nlm.nih.gov]

The diagnosis of a mood disorder can be quite challenging, having in mind the diverse clinical presentation and its variable appearance in patients. In addition, concomitant presence of anxiety disorders (social phobias, obsessive-compulsive disorders, or even panic attacks) may be noted, creating an even bigger issue to discern between the disorders [5]. For this reason, physicians must bear in mind that a long and carefully obtained patient history is the essential component during workup, as the majority of symptoms may not be evident during the hospital visit, but more importantly, because the diagnosis is made almost solely on clinical criteria [2] [5]. Not all patients will be able to describe typical changes seen in mood disorders, and some will not even admit that anything extraordinary is happening, which is why parents, close friends or even relatives can be interviewed as well. Apart from determining symptoms related to mood changes, physicians must inquire about recent use of drugs or substances that can induce such changes [3] [4], but also exclude some organic diseases that may mimic depression [5]. Thyroid hormone levels should be measured to exclude hypothyroidism, while folate, B12 and a complete blood count are recommended in the diagnostic workup as well [5].

• Sinus Arrhythmia

  Infant respiratory sinus arrhythmia (RSA) was measured in a laboratory stressor paradigm. [ncbi.nlm.nih.gov]

1. Marvel CL, Paradiso S. Cognitive and neurological impairment in mood disorders. Psychiatr Clin North Am. 2004;27(1):19-viii.
2. American Psychiatric Association. Diagnostic and statistical manual of mental disorders. Fifth Edition. Arlington, VA: American Psychiatric Publishing; 2013.
3. Quello SB, Brady KT, Sonne SC. Mood Disorders and Substance Use Disorder: A Complex Comorbidity. Science & Practice Perspectives. 2005;3(1):13-21.
4. Tolliver BK, Anton RF. Assessment and treatment of mood disorders in the context of substance abuse. Dialogues Clin Neurosci. 2015;17(2):181-190.
5. Porter RS, Kaplan JL. Merck Manual of Diagnosis and Therapy. 19th Edition. Merck Sharp & Dohme Corp. Whitehouse Station, N.J; 2011.