Bipolar disorder is, almost without exception, a life-long condition that must be carefully managed. Because there are many manifestations of the illness, it is increasingly being called bipolar spectrum disorder. The spectrum concept refers to subtypes of bipolar disorder that are sub-syndromal and typically misdiagnosed as depression. Nassir Ghaemi, M.D., has also contributed to the development of a bipolar spectrum questionnaire. The full bipolar spectrum includes all states or phases of the bipolar disorders.

Kraepelin's (1921) construct is useful for primary care clinicians, patients and families. It describes variations in two directions (mania and depression) and of three aspects: mood, activity and thinking.

According to the Mayo Clinic, in the depressive phase, signs and symptoms include: persistent feelings of sadness, anxiety, guilt, anger, isolation and/or hopelessness, disturbances in sleep and appetite, fatigue and loss of interest in daily activities, problems concentrating, irritability, chronic pain without a known cause, recurring thoughts of suicide

A 2003 study by Robert Hirschfeld, M.D., of the University of Texas Medical Branch, Galveston found bipolar patients fared worse in their depressions than unipolar patients. In terms of disability, lost years of productivity, and potential for suicide, bipolar depression, which is different (in terms of treatment), from unipolar depression, is now recognized as the most insidious aspect of the illness.

Severe depression may be accompanied by symptoms of psychosis. These symptoms include hallucinations (hearing, seeing,or otherwise sensing the presence of stimuli that are not there) and delusions (false personal beliefs that are not subject to reason or contradictory evidence and are not explained by a person's cultural concepts). They may also suffer from paranoid thoughts of being persecuted or monitored by some powerful entity such as the government or a hostile force, or become paranoid that they'll be abandoned and left by those close to them. Intense and unusual religious beliefs may also be present, such as patients' strong insistence that they have a God-given role to play in the world, a great and historic mission to accomplish, or even that they possess supernatural powers. Delusions in a depression may be far more distressing, sometimes taking the form of intense guilt for supposed wrongs that the patient believes he or she has inflicted on others.

There are a number of conflicting theories on what can be considered the cause of bipolar depression, and what may be a symptom, none of which are yet widely accepted as correct.

It is crucially important to understand that there is no blood test or brain scan that expresses distinctly that this disorder exists.

Researchers at Duke University have refined Kraepelin’s four classes of mania to include hypomania (featuring mainly euphoria) , severe mania (including euphoria, grandiosity, high levels of sexual drive, irritability, volatility, psychosis, paranoia, hostility and aggression), extreme mania (most of the displeasures, hardly any of the pleasures) also known as dysphoric mania, and two forms of mixed of mania. (where depressive and manic symptoms collide).

The Mayo Clinic and others list as additional possible symptoms of mania: elation, extreme optimism, rapid unstoppable flow of speech, racing thoughts/flights of ideas, agitation, poor judgment, recklessness or taking chances not normally taken, inordinate capacity for activity, difficulty sleeping or lesser need for sleep, tendency to be easily distracted (may constantly shift from one theme or endeavor to another), inability to concentrate, exuberant and flamboyant or colorful dress, authoritative manner, and tendency to believe they are in their best mental state.

Manic patients may be inexhaustibly, excessively, and impulsively involved in various activities without recognizing the inherent social dangers.

Symptoms of psychosis include hallucinations (hearing, seeing, or otherwise sensing the presence of stimuli that are not there) and delusions (false personal beliefs that are not subject to reason or contradictory evidence and are not explained by a person's cultural concepts). Feelings of paranoia, during which the patient believes he or she is being persecuted or monitored by the government or a hostile force. Intense and unusual religious beliefs may also be present, such as a patient's strong insistence that they have a God-given role to play in the world, a great and historic mission to accomplish, or even that they possess supernatural powers. Delusions may or may not be mood congruent.

Hypomania is a less severe form of mania, without progression to psychosis. Many of the symptoms of mania are present, but to a lesser degree than in overt mania.

People with hypomania are generally perceived as being energetic, euphoric, overflowing with new ideas, and sometimes highly confident and charismatic, and unlike full-blown mania, they are sufficiently capable of coherent thought and action to participate in everyday life.

In the context of bipolar disorder, a mixed state is a condition during which symptoms of mania (or hypomania) and clinical depression occur simultaneously (for example, agitation, anxiety, fatigue, guilt, impulsiveness, insomnia, disturbances in appetite, irritability, morbid and/or suicidal ideation, panic, paranoia, psychosis, pressured speech, indecisiveness and rage).

In at least 1/3 of people with bipolar disorder, the entire attack--or a succession of attacks--occurs as a mixed episode.

Mixed states can be the most dangerous period of mood disorders, during which panic attacks, substance abuse, and suicide attempts increase greatly.

A dysphoric mania consists of a manic episode with depressive symptoms. Increased energy and some form of anger, from irritability to full blown rage, are the most common symptoms. Symptoms may also include auditory hallucinations, confusion, insomnia, persecutory delusions, racing thoughts, restlessness, and suicidal ideation.

Alcohol, drugs of abuse, and antidepressant drugs may trigger or aggravate dysphoric mania in susceptible individuals.

Rapid cycling, defined as having four or more episodes per year, is found in a significant fraction of patients with bipolar disorder.

Ultradian cycling, in which mood cycling can also occur daily or even hourly, is less common. (Although the concept of ultradian cycling has been accepted by many psychiatrists, whether it represents true cycling is far from established.)

Numerous studies show that bipolar disorder affects a patient's ability to think and perform mental tasks, even in states of remission. Deborah Yurgelun-Todd of McLean Hospital in Belmont, Massachusetts has argued these deficits should be included as a core feature of bipolar disorder.

By the same token, research by Kay Redfield Jamison of Johns Hopkins University and others has attributed high rates of creativity and productivity to certain individuals with bipolar disorder.