Table 4.

Consensus recommendations for the diagnosis of Down syndrome regression disorder.

Category	Criteria	Possible DSRD	Probable DSRD
Symptom onset	Onset of new neurologic, psychiatric, or mixed symptoms over a period of <12 weeks in previously health individual with Down syndrome	Yes	Yes
Clinical evidence of neurologic dysfunction	1. Altered mental status or behavioral dysregulation    - Anorexia/decreased oral intake or hyperphagia    - Confusion/disorientation    - Inappropriate laughter    - Encephalopathy 2. Cognitive decline    - Apathy    - Abulia and/or avolition    - Acute memory impairment (including new difficulty with recall) 3. Developmental regression with or without new autistic features    - Social withdrawal    - Loss of previously developmental acquired milestones    - Inability to perform activities of daily living    - Stereotypy    - Rigidity around routine changes    - Decreased eye contact 4. New focal neurologic deficits on examination and/or seizure 5. Insomnia or circadian rhythm disruption 6. Language deficits    - Expressive and/or receptive aphasia    - Global aphasia (mutism)    - Whispered speech 7. Movement disorder (excluding tics)*   - Catatonia    - Bradykinesia    - Freezing    - Gait disturbance 8. Psychiatric symptoms  -Anxiety    -Delusions or hallucinations    - Derealization/depersonalization    - Obsessive compulsive tendencies  -Aggression/agitation	>3 symptom clusters present	>6 symptom clusters present
Exclusion of other etiologies	Reasonable exclusion of alternative causes of regression including other systemic and central nervous system disorders. Other primary psychiatric disorders are also considered exclusionary	Yes	Yes

^*Must be included as one of the symptom clusters for possible or probable diagnosis.