Catatonia was originally categorised as a subtype of schizophrenia, but it is found in people with other medical, neurological, and psychiatric disorders, including bipolar disorder. Catatonia is characterised by repetitive non-goal-directed movements or goal-directed movements that are executed in an idiosyncratic way, often affecting gait. Other forms of catatonia include immobility, mutism, staring, and rigidity. Tardive dyskinesia is a ‘hyper-kinetic’ (excessive movement) disorder, characterised by jerky, involuntary movements, usually of the face and/or limbs. Parkinsonism is another common movement disorder associated with schizophrenia and is a ‘hypo-kinetic’ (reduced movement) disorder, characterised by slowness of movement and rigidity. These movement disorders are associated with antipsychotic medications but can arise independent of medication status.

What is the evidence for movement disorders in people with bipolar disorder?

Moderate to low quality evidence finds the prevalence of abnormal involuntary movements in people with bipolar disorder is between 7% and 14%, while catatonic symptoms are found in around 20% of patients.

February 2022

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Neurological soft signs (NSS) are abnormalities identified by clinical examination. They are referred to as ‘soft’ because they are not related to a localised pathological lesion and are not part of a well-defined neurological syndrome.

NSS can be grouped into three categories: integrative sensory functioning, motor coordination, and complex motor sequencing. Integrative sensory functioning includes deficits in bilateral extinction (difficulty perceiving stimuli when presented to both hemispheres simultaneously), impaired audio-visual integration, agraphaesthesia (inability to recognise by touch letters and numbers drawn on the skin) and astereognosis (inability to identify an object by touch without visual input). Motor coordination involves general coordination, intention tremor, finger thumb opposition, balance, and gait. Motor sequencing measures complex motor tasks, such as repetitive alternating hand positions. Abnormalities in eye movements and developmental reflexes may also be apparent.

What is the evidence for NSS in people with bipolar disorder?

Moderate quality evidence suggests a large effect of more NSS in people with bipolar disorder than controls. This effect remained large in the subgroup analyses of bipolar disorder type, in euthymia patients, and in task type. Tasks included sensory integration, motor coordination, or motor sequencing. There were no moderating effects of age, sex, duration of illness, age of onset, or antipsychotic use.

Moderate to high quality evidence found a medium-sized effect of less NSS in people with bipolar disorder than in people with schizophrenia. Subgroup analyses showed only motor coordination scores were significantly lower in bipolar disorder. There were also no significant differences between people with bipolar disorder with psychotic symptoms, and people with schizophrenia. There were no moderating effects of age, sex, duration of illness or age of onset.

September 2021

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Olfactory processes may be dysfunctional in people with bipolar disorder. These processes are hierarchical and involve lower-order processing (detection of the stimulus) and higher-order processing (discrimination and identification of the stimulus). Measures of olfactory acuity include odor detection, identification, discrimination, intensity, and quality. Odour detection occurs at the lowest chemical concentration needed to register an odourant. Odour identification draws on a person’s knowledge and memory to correctly label the smell. Odour discrimination involves comparing the differences between multiple stimuli, judging odours as pleasant or unpleasant, or comparing the relative concentration of odours.

What is the evidence for olfactory dysfunction in people with bipolar disorder?

Moderate to low quality evidence suggests poorer olfactory identification in people with bipolar disorder than in people without a mental illness, and better olfactory identification compared to people with psychosis. Olfactory hallucinations were particularly associated with depressive episodes in people with bipolar disorder.

September 2021

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People with bipolar disorder may show disturbances in the amount or quality of sleep they receive. Typically sleep follows a characteristic pattern of four stages, where stage 1 is a state of drowsiness and early sleep; stage 2 comprises the largest component of the sleep cycle and is the first complete loss of awareness of the external environment; stage 3 is a deep, slow-wave sleep; and the fourth stage is rapid eye movement (REM) sleep where memorable dreaming and muscle paralysis occurs.

Sleep disturbance can be measured in many ways, including the total sleep time, the sleep latency (the length of time it takes from full wakefulness to sleep), and the sleep efficiency index (the amount of time spent asleep while in bed). Sleep latency can have varying definitions, particularly regarding the definition of “asleep” – some studies define this more strictly as the time from lights out until 10 consecutive minutes of stages 2, 3 or 4, while other studies define the latency more leniently as the time from lights out until the first signs of stage 2 sleep.

What is the evidence for sleep disturbance in people with bipolar disorder?

Moderate to high quality evidence suggests around 30% of people with bipolar disorder have hypersomnia. There were large effects of more time in bed and poorer sleep quality; medium-sized effects of less sleep efficacy, more sleep time (particularly stage 1, and more awakenings; and small effects of more sleep latency and wakefulness in people with bipolar disorder than in people without a mental disorder. Sleep disturbances were greater in people with bipolar disorder than in people with schizophrenia.

Sleep disturbances may be apparent prior to the onset of bipolar disorder, including during childhood and adolescence. A decreased need for sleep may precede a manic episode, while hypersomnia may precede a depressive episode. Insomnia can precede either a manic or a depressive episode.

Moderate quality evidence finds a medium-sized effect of lower relative amplitude of the sleep-wake cycle in people with bipolar disorder than people at familial or clinical risk of bipolar disorder.

September 2021

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