requested by the IRB

This study is a 12-week randomized-controlled trial of memantine hydrochloride (Namenda) for the treatment of social impairment in youth with Non-Verbal Learning Disorder, High-Functioning Autism Spectrum Disorder, and related conditions. Eligible participants will be males and females ages 8-18.

This study consists of up to 6 visits to Massachusetts General Hospital.

Inclusion Criteria:

• Male & female subjects ages 8-18 years (inclusive).
• Diagnostic Statistical Manual (DSM)-5 Autism Spectrum Disorder (ASD) diagnostic criteria as established by clinical diagnostic interview
• At least moderate severity of social impairment as measured by a total raw score of ≥85 on the parent/guardian-completed Social Responsiveness Scale-Second Edition (SRS-2)14 and a score of ≥4 on the clinician-administered Clinical Global Impression-Severity scale (CGI-S)17.

Exclusion Criteria:

• IQ ≤70 based on the Wechsler Abbreviated Scale of Intelligence-II (WASI-II) Vocabulary and Matrix Reasoning subtests
• Impaired communicative speech
• Subjects currently treated with the following medications (known to impact glutamate levels): Lamotrigine, Amantadine, N-acetylcysteine, D-cycloserine
• Subjects treated with a psychotropic medication not listed above on a dose that has not been stable for at least 4 weeks prior to study baseline.
• Co-administration of drugs that compete with memantine for renal elimination using the same renal cationic system, including hydrochlorothiazide, triamterene, metformin, cimetidine, ranitidine, quinidine, and nicotine
• Initiation of a new psychosocial intervention within 30 days prior to randomization.
• Subjects who are pregnant and/or nursing.
• Subjects with a history of non-febrile seizures without a clear and resolved etiology.
• Subjects with a history of or a current liver or kidney disease.
• Clinically unstable psychiatric conditions or judged to be at serious suicidal risk.
• Subjects who meet on the Kiddie Schedule for Affective Disorders and Schizophrenia (K-SADS-E) for alcohol or drug dependence or abuse. If the subject has a recent history of substance abuse, there will be a two-week washout period before initiating the trial as an added precaution. There are no known safety issues relating to memantine and recent history of substance abuse.
• Serious, stable or unstable systemic illness including hepatic, renal, gastroenterological, respiratory, cardiovascular (including ischemic heart disease), endocrinologic, neurologic, immunologic, or hematologic disease.
• Subjects with severe hepatic impairment (LFTs > 3 times ULN).
• Subjects with genitourinary conditions that raise urine pH (e.g., renal tubular acidosis, severe infection of the urinary tract).
• Known hypersensitivity to memantine.
• Severe allergies or multiple adverse drug reactions.
• A history of intolerance or adequate exposure to memantine, as determined by the clinician.
• Investigator and his/her immediate family defined as the investigator's spouse, parent, child, grandparent, or grandchild.