How to Score the Abnormal Involuntary Movement Scale (AIMS)
The AIMS is scored by rating involuntary movements in seven body areas on a 5-point severity scale (0-4), where 0 = none, 1 = minimal, 2 = mild, 3 = moderate, and 4 = severe, with tardive dyskinesia typically defined as a score of ≥3 (moderate) in at least one body area or ≥2 (mild) in two or more areas. 1
Examination Procedure and Body Areas Assessed
The AIMS evaluates involuntary movements across seven anatomical regions 2, 1:
- Facial and oral movements (items 1-4): Including muscles of facial expression, lips and perioral area, jaw, and tongue
- Extremity movements (items 5-6): Upper extremities (arms, wrists, hands, fingers) and lower extremities (legs, knees, ankles, toes)
- Trunk movements (item 7): Neck, shoulders, and hip areas 2
Rating Scale Structure
Each body area receives a severity score from 0 to 4 1:
- 0 = None: No abnormal movements
- 1 = Minimal: May be extreme normal movements
- 2 = Mild: Definite abnormal movements but not severe
- 3 = Moderate: Clearly abnormal movements of moderate severity
- 4 = Severe: Marked abnormal movements 2, 1
Dimensional Assessment Approach
Experienced raters achieve higher inter-rater reliability by evaluating three distinct dimensions for each movement 2:
- Quality: The specific type or character of the movement
- Frequency: How often the movement occurs
- Amplitude: The extent or range of the movement 2
This dimensional approach improves scoring consistency, though it is not formally incorporated into the standard AIMS rating system 2.
Diagnostic Criteria for Tardive Dyskinesia
The most widely accepted criterion for TD diagnosis using AIMS is a score of ≥3 (moderate symptoms) in at least one body area 1. Alternative criteria include:
- Mild symptoms (score ≥2) in two or more anatomical areas 3
- The prevalence of TD decreases as more stringent severity criteria are applied 1
Cross-Scale Validation
When comparing AIMS to the Extrapyramidal Symptom Rating Scale (ESRS), there is 96% agreement in TD diagnosis when using equivalent severity thresholds 3:
- AIMS "mild" (score = 2) corresponds to ESRS scores of 2-3
- AIMS "moderate or greater" (score ≥3) corresponds to ESRS scores ≥4 3
Critical Implementation Considerations
Experience with TD significantly influences scoring accuracy and inter-rater reliability 2. Key factors for reliable assessment include:
- Training requirements: Experienced raters demonstrate higher agreement levels and more consistent scoring over time compared to inexperienced raters 2
- Annual training: Implementing structured one-hour AIMS training sessions for clinicians can increase documentation compliance from 3% to 87% 4
- Systematic evaluation: The AIMS provides reliable assessment when used consistently by trained evaluators 1
Limitations and Evolving Standards
The AIMS was designed primarily to assess anatomic distribution and severity without detailed phenomenologic characterization 5. Current limitations include:
- Lack of formal incorporation of movement quality, frequency, and amplitude dimensions 2
- Limited assessment of functional impairment in daily activities 5
- Need for updated tools to capture the expanding phenomenologic heterogeneity of tardive syndromes 5
Despite these limitations, the AIMS remains the standard instrument for TD assessment in both clinical practice and research settings 1, 5.