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The YGTSS is the dominant tic severity measure in Tourette’s syndrome and chronic motor or vocal tic disorders. You rate motor and phonic tic severity across five dimensions each, plus an overall impairment rating. You fill it about the client after a clinical observation interview; the client never sees the form.

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What it measures

Motor and phonic (vocal) tics, each rated across five dimensions on a 0-5 scale:
DimensionWhat it captures
NumberSingle tic / 2-5 / >5 / discrete + orchestrated / cannot distinguish
FrequencyLess than daily / daily with intervals / regular / virtually every waking hour / continuous
IntensityLess than voluntary / similar to voluntary / exaggerated / forceful / extreme with injury risk
ComplexityAll simple / borderline / some clearly complex / orchestrated bouts / bizarre or obscene
InterferenceNone / no interruption / occasional interruption / frequent interruption / prohibits action
Plus one Overall Impairment item, scored in 10-point increments (0/10/20/30/40/50) — measuring impact on self-esteem, family life, social acceptance, and school or work functioning.

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When to use it

  • Tic disorder severity tracking — Tourette’s syndrome and chronic motor or phonic tic disorder
  • CBIT (Comprehensive Behavioral Intervention for Tics) treatment response
  • Pharmacotherapy monitoring — clonidine, guanfacine, dopamine antagonists, VMAT2 inhibitors
  • Comorbid OCD differential — often paired with the Y-BOCS, since roughly half of Tourette’s cases carry comorbid OCD
  • Coprolalia documentation — the content rating captures coprolalia, palilalia, and echolalia for the clinical record

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How you fill it

Solo fill. Open Templates, pick YGTSS, tap New response. The renderer presents the ten tic-dimension items in two groups (Motor / Phonic) with section headers, followed by the Overall Impairment item with the canonical 0/10/20/30/40/50 anchors. Typical administration is 20-30 minutes with a focused observation period. The form never goes to the client.

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How Rivet scores it

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Total + subscales

  • Motor Tic Score: sum of 5 motor dimensions, 0-25
  • Phonic Tic Score: sum of 5 phonic dimensions, 0-25
  • Total Tic Score: Motor + Phonic, 0-50
  • Overall Impairment: single 0-50 rating
  • Global YGTSS: Total Tic Score + Overall Impairment, 0-100
The Overall Impairment is separate from the Total Tic Score, not added to it. They form the Global YGTSS together but are reported independently.

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Severity bands (Storch et al. 2005) — Total Tic Score

Total Tic ScoreBand
0-9Minimal tics
10-19Mild tics
20-29Moderate tics
30-39Marked tics
≥40Severe tics

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Clinical change threshold

  • Response: ≥25% reduction in Total Tic Score, paired with at least “much improved” on the CGI-Improvement (Cohen 2013)

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Rater training

The YGTSS Rater Manual (Leckman, distributed by Yale Child Study Center) and the CBIT manual (Cohen et al. 2013, Behaviour Research and Therapy 51:759-769) provide standardized anchors and observation protocols. Inter-rater reliability with trained raters typically reaches ICC 0.84+.

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What we render vs. the source

Verbatim Leckman 1989 items with the published severity anchors. The ten tic dimensions are presented in two groups (Motor / Phonic) with section headers for visual chunking. The Overall Impairment item uses the canonical 0/10/20/30/40/50 increments rather than an arbitrary 0-50 scale — Leckman 1989 intentionally chose six anchors at 10-point intervals.

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Known limitations

  • The Number / Frequency / Intensity / Complexity / Interference rubric requires clinical judgment for each dimension. Borderline ratings may vary between raters.
  • The impairment rating relies on patient or parent report of impact on self-esteem, family life, social acceptance, and school or work functioning. These can be confounded by comorbid OCD or ADHD impairment — pair with Y-BOCS or an ADHD measure to disambiguate.
  • The scale doesn’t differentiate well between transient tic disorder (less than 1 year) and chronic. Pair with DSM-5 history.

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Citations

  • Leckman, J. F., Riddle, M. A., Hardin, M. T., Ort, S. I., Swartz, K. L., Stevenson, J., & Cohen, D. J. (1989). “The Yale Global Tic Severity Scale: initial testing of a clinician-rated scale of tic severity.” Journal of the American Academy of Child and Adolescent Psychiatry, 28(4): 566-573. Free clinical use per Yale Child Study Center.
  • Storch, E. A., Murphy, T. K., Geffken, G. R., Sajid, M., Allen, P., Roberti, J. W., & Goodman, W. K. (2005). “Reliability and validity of the Yale Global Tic Severity Scale.” Psychological Assessment, 17(4): 486-491.
  • Cohen, S. C., Leckman, J. F., & Bloch, M. H. (2013). “Clinical assessment of Tourette syndrome and tic disorders.” Behaviour Research and Therapy, 51(11): 759-769.

Y-BOCS

Yale-Brown Obsessive Compulsive Scale. Frequently paired with YGTSS in tic-related OCD presentations.

Clinician-administered overview

Why these six measures don’t ship to clients, and how solo fill works.