What are akathisia and tardive dyskinesia, and what are their similarities and differences?

Akathisia and Tardive Dyskinesia: Definitions, Similarities, and Differences

Akathisia is a subjective disorder characterized by inner restlessness and an inability to sit still, while tardive dyskinesia is an involuntary movement disorder with repetitive purposeless movements, typically involving the mouth and tongue—both are antipsychotic-induced movement disorders but differ fundamentally in their subjective versus involuntary nature. 1

Core Definitions

Akathisia

• Fundamentally a subjective disorder characterized by a desire to be in constant motion, resulting in an inability to sit still and a compulsion to move 1
• Presents with restlessness and dysphoria as primary features 2
• The patient experiences and reports the distressing sensation of needing to move 1

Tardive Dyskinesia

• An involuntary movement disorder characterized by repetitive purposeless movements 1
• Typically involves the buccolingual masticatory areas (mouth, tongue, jaw) but can include choreoathetoid limb movements 1
• Movements are irregular, stereotyped, and choreiform 3
• Patients may not be aware of or distressed by the movements themselves 4

Key Similarities

Both conditions share important commonalities:

• Both are caused by dopamine receptor blocking agents (DRBAs), particularly antipsychotic medications 4, 5
• Both can occur with long-term neuroleptic treatment 2
• Both are common in patients receiving antipsychotic therapy (akathisia in 36% and TD in 23.5% of surveyed patients) 6
• Both can significantly impact quality of life and contribute to medication non-adherence 6, 7

Critical Differences

1. Nature of the Disorder

• Akathisia: Subjective distress with voluntary movements in response to inner restlessness 1
• Tardive Dyskinesia: Involuntary movements that occur without conscious control 1

2. Time of Onset

• Akathisia: Can occur acutely (within days to weeks of starting or increasing antipsychotic dose) 8
• Tardive Dyskinesia: Develops after prolonged exposure to antipsychotics (months to years) 4

3. Location of Symptoms

• Akathisia: Primarily affects the legs and trunk, with characteristic coarse, jerky foot tremor as an invariable accompaniment 8
• Tardive Dyskinesia: Predominantly involves orofacial regions (tongue, lips, jaw) but can affect limbs 1, 4

4. Subjective Experience

• Akathisia: Marked by intense subjective distress and dysphoria that the patient can describe 2, 1
• Tardive Dyskinesia: Often lacks subjective awareness; patients may not recognize or be bothered by their movements 1

5. Response to Treatment

• Akathisia: Responds to dose reduction, switching to quetiapine or olanzapine, or adjunctive propranolol (10-30 mg two to three times daily) 9; also responds to benzodiazepines or beta-blockers 10
• Tardive Dyskinesia: Requires VMAT2 inhibitors (deutetrabenazine or valbenazine) for moderate to severe cases 10, 5; may improve with switching to clozapine or quetiapine 3

Special Consideration: Tardive Akathisia

A third entity exists called "tardive akathisia," which represents a variant that combines features of both disorders:

• Has the pharmacologic characteristics of tardive dyskinesia (develops after prolonged exposure, persists after drug withdrawal) 8
• Maintains the subjective restlessness of akathisia 2
• Considered one of the behavioral variants of TD 2
• May represent an evolution from acute akathisia or a distinct disorder 1

Clinical Pitfalls to Avoid

Diagnostic Confusion

• Do not confuse pseudoakathisia (motor signs without subjective symptoms) with true akathisia 8
• Recognize that both disorders can coexist in the same patient, complicating diagnosis and management 4
• A significant association exists between chronic akathisia and choreoathetoid limb dyskinesias 8

Assessment Requirements

• Duration of DRBA exposure helps differentiate acute akathisia from tardive syndromes 4
• Presence of other extrapyramidal symptoms should be documented 1
• The voluntary versus involuntary nature of movements is the most critical distinguishing feature 1

Management Errors

• Never increase antipsychotic dose for akathisia, as this worsens the condition 9
• Anticholinergic medications are not appropriate for akathisia (they treat acute dystonia and parkinsonism) 10
• For TD, withdrawal of antipsychotics is first-line only if clinically feasible; many patients with serious mental illness cannot discontinue due to relapse risk 3