Mixed episode and mixed features

Article written and reviewed by Dr Luca Moretti

The concept of a mixed affective state describes the coexistence, during the same period, of manifestations belonging to the manic and depressive polarities. This is an area in which terminology must be used with particular precision, because DSM-5-TR and ICD-11 adopt different diagnostic models and the term “mixed episode” no longer has the same meaning in the two systems.

In DSM-5-TR, the mixed episode that existed in DSM-IV is no longer a separate category. The manual first identifies the principal episode, manic, hypomanic, or major depressive, and then applies the with mixed features specifier when at least three specific symptoms of the opposite polarity are present. An episode in which all criteria for both mania and depression are simultaneously met is therefore classified within the manic domain with mixed features rather than as a separate category called mixed episode.

The ICD-11 CDDR 2024, by contrast, retains a true mixed episode. It is characterized by several prominent manic symptoms and several prominent depressive symptoms, present simultaneously or alternating very rapidly, even from one day to the next or within the same day. The presentation must include a depressed, dysphoric, euphoric, or expansive mood disturbance and must cause clinically significant impairment or be accompanied by delusions or hallucinations.

The minimum ICD-11 duration for a first presentation is two weeks, unless the episode is shortened by treatment. When a person with bipolar I disorder has previously experienced manic or mixed episodes, ICD-11 allows a new mixed episode to be recognized without necessarily waiting two weeks if all other diagnostic requirements are met.

These differences explain why there is no single reliable epidemiological estimate for “mixed episode.” Studies using the former DSM-IV criteria, the DSM-5 specifier, dimensional definitions, or ICD criteria identify different populations. The literature nevertheless consistently shows that mixed manifestations are clinically common in bipolar disorder and are associated with a more complex course than purely polar presentations.

The clinical significance is particularly important because activation, impulsivity, and reduced sleep may coexist with depression, guilt, hopelessness, and suicidal ideation. The simultaneous presence of energy and thoughts of death makes a thorough safety assessment mandatory and prevents these presentations from being regarded as simple intermediate forms between depression and mania.

Etiology, pathogenesis, and pathophysiology

No specific biological cause has been identified that universally distinguishes mixed states from other mood episodes. Mixed presentations are clinical phenotypes that emerge in the context of bipolar disorders or, in the DSM system, also during a major depressive episode in a person with no previous manic or hypomanic episodes.

When the mixed state is part of a bipolar disorder, it shares the disorder’s complex genetic vulnerability. Genome-wide studies demonstrate a highly polygenic architecture, with numerous small-effect variants and partial genetic overlap with other psychiatric disorders. No genetic variants have been identified that can specifically identify a mixed presentation.

A family history of bipolar disorder increases the likelihood that activation symptoms during a depressive phase belong to the bipolar spectrum, but it is not a diagnostic criterion. Diagnosis must be based on the entire history of episodes rather than on a single risk factor.

Circadian regulation and sleep systems may contribute to destabilization. A patient may simultaneously experience insomnia or decreased need for sleep, acceleration, tension, and profound dysphoria. Sleep reduction can amplify both activation and emotional instability.

Dopaminergic, glutamatergic, GABAergic, serotonergic, and noradrenergic systems have been studied in bipolar disorders, but there is no neurotransmitter signature capable of separating pure mania, depression, and mixed states. The phenomenology likely results from the interaction of multiple networks rather than from the simple sum of a “manic excess” and a “depressive deficit.”

Brain networks involved in reward and motivation may be simultaneously activated while circuits involved in negative appraisal, threat, and self-referential processing contribute to dysphoria, guilt, or hopelessness. Such models are consistent with the coexistence of energy and distress but remain group-level neurobiological models rather than individual diagnostic tools.

Neuroimaging studies in bipolar disorder show average cortical and subcortical alterations, but no specific pattern has been validated for the mixed episode. MRI, PET, and functional neuroimaging should therefore not be used to confirm the diagnosis.

Immune-inflammatory, neuroendocrine, metabolic, and oxidative-stress alterations have been documented in mood disorders, but their distribution varies with illness phase, treatment, and comorbidity. None of these parameters is necessary or sufficient for a mixed state.

Medications and substances can produce combinations of depressive and activation symptoms. Stimulants can induce euphoria, irritability, and acceleration; withdrawal can instead produce dysphoria and depression. Rapid succession of these two phenomena can mimic a mixed state and requires a precise toxicological history.

Antidepressants are particularly relevant in bipolar disorders because they may be associated with the emergence of hypomania, mania, agitation, or mixed features in some patients. The mere appearance of irritability or insomnia does not demonstrate a bipolar switch, but a complete syndrome persisting beyond the physiological effects of treatment must be interpreted according to international diagnostic criteria.

Corticosteroids, dopaminergic drugs, and other substances can contribute to secondary affective syndromes. As with other mood episodes, the causal relationship depends on timing, dose, previous psychiatric history, remission after withdrawal, and biological plausibility.

Neurological and endocrine conditions can produce agitation, lability, dysphoria, and manic-like symptoms. An atypical first episode, especially at an older age or associated with neurological findings, therefore requires a work-up directed toward possible secondary causes.

Psychosocial stress may precede mixed presentations but is not a necessary cause. In a vulnerable individual, changes in sleep, daily rhythms, and substance exposure may interact and contribute to loss of affective stability.

An important conceptual feature is that mixed presentations do not necessarily represent a simple transition phase between two distinct episodes. Symptoms of the two polarities may coexist stably during the same period and constitute the core of the syndrome itself.

The different diagnostic constructions of DSM and ICD reflect precisely this complexity. DSM prioritizes identification of a predominant episode to which selected opposite-polarity symptoms are added; ICD-11 instead recognizes that a sufficiently broad and severe combination of the two symptom groups can constitute a separately defined mixed episode.

Clinical manifestations

The patient may present with an apparently contradictory combination of activation and depression. They may report hopelessness, psychological pain, and thoughts of death while simultaneously showing rapid speech, restlessness, racing thoughts, reduced sleep, and impulsive behavior.

The history should reconstruct depressive and manic symptoms separately without assuming that the presence of one group excludes the other. It is necessary to establish which symptoms are concurrent, which alternate rapidly, and which instead belong to temporally distinct episodes.

When the manic component predominates, euphoria, grandiosity, decreased need for sleep, increased talkativeness, and hyperactivity may be present, but accompanied by dysphoria, loss of interest, feelings of worthlessness, hopelessness, or suicidal ideation.

When the depressive component predominates, the patient may appear profoundly depressed while simultaneously reporting increased energy, racing thoughts, increased talkativeness, decreased need for sleep, impulsivity, or increased goal-directed activity.

Irritability is very common in mixed clinical presentations, but it has a different nosographic significance in the two systems. It is explicitly relevant in the ICD-11 description, whereas DSM-5-TR does not use it among the opposite-polarity symptoms required for the specifier because it can occur in both depression and mania.

The same applies to psychomotor agitation and distractibility, which are excluded from the DSM count of opposite-polarity symptoms to reduce phenomenological overlap. Their exclusion from the specifier criteria does not mean that they are not clinically common or important.

Thought may be rapid, crowded, and difficult to control while its content remains pessimistic or suicidal. This combination of formal acceleration and depressive content is one of the most clinically characteristic presentations of mixed states.

Sleep disturbances must be analyzed precisely. A depressed patient may have insomnia and feel exhausted, whereas decreased need for sleep implies the ability to function with less sleep. The presence of the latter phenomenon during depression increases suspicion of opposite-polarity activation.

Impulsivity may coexist with hopelessness and increase the dangerousness of the presentation. Spending, substance use, risky sexual behavior, reckless driving, or aggression may occur simultaneously with feelings of worthlessness and thoughts of death.

Mood lability may be evident, with rapid shifts among euphoria, irritability, anxiety, crying, and dysphoria. In ICD-11, a mixed episode may include very rapid alternations even within the same day, provided the overall presentation meets the other required characteristics.

Psychotic symptoms may occur in ICD-11 mixed episodes and in manic or depressive episodes with psychotic and mixed features in DSM. Grandiose delusions may coexist with guilt, persecution, or nihilism and make behavior particularly unpredictable.

Anxiety may be intense and associated with tension, agitation, a sense of impending catastrophe, and inability to stop the flow of thoughts. Anxiety and agitation should not automatically be interpreted as mixed features, but they require investigation for specific manic symptoms.

Suicidality must be assessed directly. The simultaneous presence of hopelessness, thoughts of death, high energy, and impulsivity may represent a particularly concerning risk profile. No scale can predict suicidal behavior with certainty, and assessment must be clinical and repeated.

Mental status examination may show a patient who is simultaneously dysphoric and hyperactive, with rapid speech but negative content, marked irritability, rapidly variable affect, and impaired judgment. Severe cases may include agitation, psychosis, or inability to maintain safety.

Information from family members and close contacts helps establish the temporal sequence of symptoms. A patient may remember only the depressive component or, conversely, minimize dysphoria and describe mainly the increase in energy.

The presentation must be distinguished from simple agitated depression. Agitation, anxiety, and insomnia can occur in depression without true manic-polarity symptoms. Identification of mixed features therefore requires application of the specific criteria of the diagnostic system being used.

Assessment and diagnosis

Diagnosis first requires specifying which nosographic system is being used. Writing generically “mixed episode according to DSM-5-TR” is incorrect because DSM-5-TR has no such separate category. Conversely, referring only to the mixed-features specifier does not fully describe the ICD-11 classification.

In DSM-5-TR, the with mixed features specifier may be applied to a manic or hypomanic episode when at least three specific depressive symptoms are present on most days of the episode.

During a manic or hypomanic episode, the DSM-5-TR with mixed features specifier requires at least three of the following concurrent depressive symptoms.

• Prominent dysphoric or depressed mood.
• Markedly diminished interest or pleasure in all, or almost all, activities.
• Psychomotor retardation.
• Fatigue or loss of energy.
• Feelings of worthlessness or excessive or inappropriate guilt.
• Recurrent thoughts of death, suicidal ideation, or suicidal behavior.

When the predominant episode is instead a major depressive episode, the same DSM specifier requires at least three specifically selected manic or hypomanic symptoms.

During a major depressive episode, the DSM-5-TR with mixed features specifier requires at least three of the following concurrent manic or hypomanic symptoms.

• Elevated or expansive mood.
• Increased self-esteem or grandiosity.
• Increased talkativeness or pressure to keep talking.
• Flight of ideas or subjective experience that thoughts are racing.
• Increase in energy or goal-directed activity.
• Increased or excessive involvement in activities with a high potential for negative consequences.
• Decreased need for sleep.

The opposite-polarity symptoms must represent a change from usual behavior and be observable by others. Irritability, distractibility, and psychomotor agitation are not included in the DSM count of opposite-polarity symptoms because they substantially overlap between the two poles, although they may be clinically prominent.

If, during depression, the full criteria for a true manic episode are met, the patient is not simply classified as having major depressive disorder with mixed features: the presence of mania leads to a diagnosis of bipolar I disorder once secondary causes have been excluded.

ICD-11 instead uses its own requirements for mixed episode. Several prominent manic symptoms and several prominent depressive symptoms must be present, either simultaneously or in very rapid alternation, with a mood disturbance consistent with one or both polarities.

According to ICD-11 CDDR, recognition of a mixed episode requires several prominent manic symptoms and several prominent depressive symptoms, simultaneous or rapidly alternating, with a mood disturbance present for most of the day nearly every day for at least two weeks unless shortened by treatment.

• The presentation includes a mood disturbance that may be depressed, dysphoric, euphoric, or expansive.
• Significant manifestations belonging to both polarities must be present.
• The symptoms must cause significant functional impairment or be accompanied by delusions or hallucinations.
• The symptoms must not be better explained by the effects of a substance, medication, or medical condition.

In ICD-11, a history of a manic or mixed episode is sufficient for bipolar I disorder. A mixed episode therefore does not belong to the definition of bipolar II disorder, which requires hypomanic and depressive episodes without any history of mania or mixed episode.

The ICD-11 two-week duration threshold has an important longitudinal exception: in a person who has already experienced manic or mixed episodes, a new mixed episode may be recognized earlier when all other requirements are met.

Diagnostic assessment must immediately include suicide risk. Thoughts of death, intent, planning, access to means, previous attempts, impulsivity, agitation, psychosis, substance use, and the patient’s ability to collaborate in maintaining safety should be explored.

Collateral information from family members may be essential to establish whether symptoms are truly simultaneous or instead represent a succession of separate episodes. This is particularly important when the patient has poor insight or rapid lability.

Mania and depression rating scales can quantify the respective dimensions but do not replace diagnosis. There is no laboratory or instrumental test pathognomonic for mixed states.

Complete blood count, electrolytes, renal and hepatic function, thyroid function, toxicology testing, pregnancy testing, and other investigations are selected according to history, physical examination, and planned treatment. Neuroimaging and EEG are reserved for cases with suspected neurological disease or an atypical presentation.

The differential diagnosis first includes depression with agitation but without true manic symptoms. Anxiety, insomnia, irritability, and restlessness alone are insufficient to apply the DSM specifier.

ADHD can produce distractibility, hyperactivity, and impulsivity, but typically has a persistent course beginning during development. Bipolar disorder requires an episodic change in mood and energy.

Borderline personality disorder may be characterized by intense lability and impulsivity, but fluctuations are generally embedded in a pervasive pattern and are often closely reactive to interpersonal relationships. Differential diagnosis should be based on temporality and the entire syndromic profile.

Stimulant intoxication, withdrawal, corticosteroids, and other medications can produce mixed symptoms. Medication-induced akathisia can also mimic manic agitation and should be recognized through its temporal relationship with antipsychotics or other drugs and the characteristic motor restlessness.

Rapid cycling is not synonymous with a mixed episode. It describes a course of bipolar disorder characterized by a high frequency of distinct episodes during the year, whereas a mixed state concerns the simultaneous presence or rapid alternation of symptoms of the two polarities within the same clinical period.

Treatment and prognosis

Treatment of mixed states is more complex than treatment of classic polar presentations and depends first on the underlying diagnosis. Mania with mixed features, bipolar depression with mixed features, unipolar major depression with mixed features, and an ICD-11 mixed episode should not be treated as though they were perfectly equivalent entities.

The first priority is safety. The combination of depressive symptoms, agitation, impulsivity, reduced sleep, and increased energy requires direct and repeated assessment of suicidality. Hospitalization or intensive treatment should be considered when risk cannot be managed safely in a less restrictive setting.

Precipitating factors should be corrected: discontinuation of substances, treatment of intoxication or withdrawal, normalization of sleep, and reduction of stimulation. In a patient with bipolar disorder who develops a mixed presentation during antidepressant treatment, therapy should be reassessed promptly.

The CANMAT/ISBD 2021 recommendations are particularly important because they specifically evaluate mixed presentations. The key finding is that no treatment reached the level required to be recommended as first-line for DSM-5 manic or depressive episodes with mixed features, reflecting the limited quality of specific evidence.

For mania with mixed features according to DSM-5, CANMAT/ISBD identifies asenapine, cariprazine, divalproex, and aripiprazole as second-line options. Selection should be individualized according to severity, psychosis, previous responses, and adverse-effect profile.

For bipolar depression with mixed features, CANMAT/ISBD 2021 lists cariprazine and lurasidone among second-line options supported by the available evidence. These recommendations should not be automatically transferred to unipolar major depression with mixed features.

For the former DSM-IV mixed episode, for which a larger evidence base exists, CANMAT/ISBD identifies asenapine and aripiprazole as first-line options and olanzapine, carbamazepine, and divalproex as second-line options. It is essential to specify that this hierarchy derives from a nosographic definition that is not equivalent to the DSM-5 specifier.

Antidepressants require particular caution. In patients with bipolar disorder and mixed features, antidepressant monotherapy should be avoided, and international guidelines also recommend caution with adjunctive use when there is marked activation or a history of switching.

In a patient who instead meets criteria for major depressive disorder with mixed features but has never had mania or hypomania, the evidence is different and it is methodologically incorrect to apply bipolar-disorder algorithms automatically. It is nevertheless essential to monitor carefully for the emergence of greater activation and to continue reassessing the diagnosis longitudinally.

Lithium remains a fundamental medication in the treatment and maintenance of bipolar disorder, but the presence of mixed features may influence acute-treatment selection and, in some patients, make a strategy based on antipsychotics or other stabilizers with phenotype-specific evidence more appropriate.

Valproate has evidence in manic and mixed presentations, but its use must strictly comply with AIFA and EMA restrictions. It is contraindicated for bipolar disorder during pregnancy and is subject to stringent pregnancy-prevention measures in women of childbearing potential; specific precautions for treated men are also in force.

When the presentation includes severe psychosis, agitation, or behavioral risk, antipsychotics are a central component of treatment. The individual metabolic, neurological, endocrine, and cardiovascular risk profile should guide selection.

Electroconvulsive therapy may be considered in severe and treatment-resistant affective presentations, when a rapid response is needed, when previous treatments have failed, or in the presence of catatonia. The decision should be specialist-led and accompanied by planning of continuation treatment.

Environmental management includes reducing stimulation, stabilizing the sleep-wake rhythm, and limiting access to means or situations that facilitate impulsive behavior. In severe cases, these measures complement rather than replace pharmacotherapy.

Psychosocial interventions become more important after acute instability has been controlled. Psychoeducation, family interventions, cognitive behavioral therapy, and rhythm-stabilization strategies can improve adherence and recognition of prodromal signs.

Maintenance therapy after a mixed presentation should be individualized. CANMAT/ISBD emphasizes that specific evidence following DSM-5 mixed states is limited; for former DSM-IV presentations, more consistent data exist for quetiapine and other maintenance strategies, but the different diagnostic definition must be remembered.

Prognosis tends to be more complex than in presentations without opposite-polarity symptoms. Clinical studies associate mixed features with greater recurrence, comorbidity, psychotic symptoms, substance use, longer time to remission, and higher suicide risk.

These associations describe populations and do not allow the course of an individual patient to be predicted with certainty. Prognosis depends on the underlying diagnosis, severity, previous episodes, treatment, adherence, comorbidity, and continuity of care.

Remission of the acute episode should be followed by monitoring of residual symptoms from both the depressive and manic polarities. A person who is apparently no longer depressed may retain subthreshold activation and vice versa, with implications for risk and relapse prevention.

Complications

The most clinically important complication of mixed presentations is the high risk of suicidal behavior. The coexistence of hopelessness, agitation, acceleration, and impulsivity can make the clinical situation particularly unstable.

There is, however, no combination of symptoms that can predict suicide with certainty. Risk should be reassessed over time by considering ideation, intent, access to means, previous attempts, psychosis, substances, available support, and recent clinical course.

Impulsivity can lead to accidents, dangerous driving, risky sexual behavior, uncontrolled spending, and other decisions with persistent consequences. The depressive component does not protect against these behaviors and may instead coexist with them.

Problematic use of alcohol or other substances may develop or intensify during a mixed state, contributing to disinhibition, insomnia, and reduced adherence. Substance-use comorbidity also complicates the diagnostic process.

Insomnia or decreased need for sleep can further fuel destabilization. Progressive sleep loss can worsen both the manic component and irritability, anxiety, and disorganization.

Relational and occupational conflicts may arise from the combination of irritability, impulsivity, pessimism, and disinhibition. The patient may simultaneously perceive themselves as a failure and react aggressively to criticism, with substantial social consequences.

Psychotic symptoms may increase the risk of dangerous decisions or refusal of care. As in other mood episodes, psychosis is a clinical feature of the presentation and should not be simplistically described as a complication that appeared after the episode.

A presentation initially interpreted as unipolar depression with mixed features may, during follow-up, be reclassified if a true hypomanic or manic episode emerges. Longitudinal diagnosis should therefore remain open to new clinical evidence.

Inappropriate prescription of antidepressants in a person with bipolar disorder may contribute to further activation or instability in some patients. This iatrogenic risk underscores the importance of systematically assessing opposite-polarity symptoms before and during treatment.

Marked impairment may lead to job loss, financial difficulties, deterioration of relationships, and need for hospitalization. Recovery therefore often requires interventions that continue beyond simple reduction of acute symptoms.

Incomplete remission may leave residual symptoms of both polarities, increasing vulnerability to subsequent exacerbations. Monitoring should include sleep, energy, thought, mood, activity, and suicidal ideation.

Finally, the treatments used may produce metabolic, neurological, renal, thyroid, or reproductive complications. Appropriate specialist management should integrate efficacy, relapse prevention, and systematic monitoring of medication safety.

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