Ergoloid mesylates 1 mg will be mixed with methyl cellulose and placed in a size 00 capsule. During the EM Treatment Period (Period 1) and 5-HTP/EM Treatment Period (Period 2), subjects will take 1 capsule of EM 3 times per day.

Matching placebo for Ergoloid mesylates will be ascorbic acid powder in identical size 00 capsules. During the 5-HTP Treatment Period (Period 3) and Placebo Treatment Period (Period 4), subjects will take 1 capsule of matching placebo for EM 3 times per day.

Matching placebo for 5-Hydroxytryptophan will be ascorbic acid powder in identical size 00 capsules. During the EM Treatment Period (Period 2) and Placebo Treatment Period (Period 4), subjects will take 1 capsule of matching placebo for 5-HTP 3 times per day.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The distractibility subtest measures how easily the subject is distracted by extraneous stimuli. This subtest requires subjects to tap a button when a target stimulus appears on the screen while ignoring distracters that appear shortly before the stimulus. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean number of correct responses and errors were recorded, and change from baseline was calculated. For the distractability subtest, a higher mean number of correct responses and lower mean number of errors over the 3 minutes indicates better performance.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The distractibility subtest measures how easily the subject is distracted by extraneous stimuli. This subtest requires subjects to tap a button when a target stimulus appears on the screen while ignoring distracters that appear shortly before the stimulus. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean number of correct responses and errors were recorded, and change from baseline was calculated. For the distractability subtest, a higher mean number of correct responses and lower mean number of errors over the 3 minutes indicates better performance.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The flexibility subtest measures the subject's ability to be flexible about shifting from one response type to another. This subtest is 2 minutes long and requires subjects to alternate between identifying blue and green dragons which seem on random sides of the screen by tapping one of two buttons. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean number of correct responses and errors were recorded and change from baseline was calculated. For the flexibility subtest, a higher mean number of correct responses and lower mean number of errors indicates better performance.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The flexibility subtest measures the subject's ability to be flexible about shifting from one response type to another. This subtest is 2 minutes long and requires subjects to alternate between identifying blue and green dragons which seem on random sides of the screen by tapping one of two buttons. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean number of correct responses and errors were recorded and change from baseline was calculated. For the flexibility subtest, a higher mean number of correct responses and lower mean number of errors indicates better performance.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The Go-NoGo subtest measures a subject's impulsivity by requiring subjects to tap a button when the target stimulus is presented, while refraining from hitting the button for the non-target stimulus. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). This subtest takes place over 2 minutes 30 seconds. Mean number of correct responses and errors were recorded, and change from baseline was calculated. For the Go-NoGo subtest, a higher mean number of correct responses and a lower mean number of errors indicates better performance.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The Go-NoGo subtest measures a subject's impulsivity by requiring subjects to tap a button when the target stimulus is presented, while refraining from hitting the button for the non-target stimulus. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). This subtest takes place over 2 minutes 30 seconds. Mean number of correct responses and errors were recorded, and change from baseline was calculated. For the Go-NoGo subtest, a higher mean number of correct responses and a lower mean number of errors indicates better performance.

The Clinical Global Impression-Severity (CGI-S) is a global measure to provide a clinical judgment of a participant's overall condition based on a trained clinician's assessment of cognition, behavior and activities of daily living. The clinician compares the subject with individuals of the same age and sex. The assessment of severity is with a 7-point scale: 1, not ill; 2, very mild; 3, mild; 4, moderate; 5, marked; 6, severe; 7, extremely severe. A net decrease in severity score over time indicates a positive outcome.

This assessment is a parent/caregiver-rated scale with six subscales to assess irritability, stereotypes, lethargy, hyperactivity, inappropriate speech, and social avoidance, using ABC-FX factoring system. The ABC was was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean score for each subscale was measured and change from baseline was calculated. Lower mean scores on each subscale indicate fewer aberrant behaviors (better functioning).The range of possible scores on each subscale are irritability (0-54), lethargy (0-39), stereotypes (0-18), hyperactivity (0-30), inappropriate speech (0-12), and social avoidance (0-12).

The ADAMS is a parent/caregiver rated scale with five subscores to assess manic/hyperactive behavior, depressed mood, social avoidance, general anxiety, and obsessive/compulsive behavior. The ADAMs was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean score for each subscale was recorded, and change from baseline was calculated for each subscore. The range of possible scores for each subscale is 0-21. Lower mean scores on each subscale indicate better functioning.

VABS-3 is a clinician-administered standardized interview. For this study, we collected data in domains of communication (receptive & written language), daily living skills (domestic & community skills), & socialization (interpersonal relationships, play & leisure time, & coping abilities). This assessment was administered at Baseline as well as at Week 4, Week 8, Week 12, and Week 16 (end of each treatment period). Mean growth scale value (GSV) for each subdomain was recorded at each time point and change from baseline was calculated. The possible GSVs for each subdomain are receptive (10-162), written (10-163), domestic (10-110), community (10-136), interpersonal (10-152), play and leisure (10-164), & coping skills (10-120). Higher GSVs for each subdomain indicate better functioning.

The NIH-TCB is a battery of extensively validated computer-administered cognitive tests. The NIH-TCB includes 7 evaluations measuring cognitive flexibility, inhibition & visual attention, episodic memory, immediate recall & sequencing of different visually & orally presented stimuli, processing speed, recognition of letters and words, & receptive vocabulary. This assessment was administered at Baseline as well as at Week 4, Week 8, Week 12, and Week 16 (end of each treatment period). This battery produces fluid and crystallized cognition composite scores. The Total Cognition Composite Score is found by converting raw fluid and crystallized scores to standard scores, averaging these two scores, then deriving standard scores based on this new distribution. Scores range from 0-140. The normative mean of the uncorrected standard score is 100 and the standard deviation is 15. A higher mean total cognition composite score indicates better performance.

IIn an attempt to measure the level of behavioral difficulty experienced by the parent/caregiver with respect to the child with FXS, the VAS allows parents to mark on a visual line measuring 10 cm with one side marked "worst behavior" and the other side marked "best behavior." The caregiver rated the participant's behavior with respect to three domains: daily functioning, anxiety/irritability and language. Distances closer to 10 cm are considered worse behavior and distances closer to 0 cm are considered better behavior. Average distance of the mark was recorded for each domain at Baseline then again at Week 4, Week 8, Week 12, and Week 16 (end of each treatment period). Change from baseline was calculated for each domain. Lower scores indicate a better outcome (closer distance to best behavior side).

Event-Related Potentials (ERPs) enable extraction of neural responses associated with specific sensory, cognitive, or motor events from an overall EEG. Gamma 1 and gamma 2 waves were measured for various parts of the brain at a resting state. ERP was performed at Baseline as well as at Week 4, Week 8, Week 12, Week 16 (at the end of each treatment period). Mean power of gamma 1 and gamma 2 bands, measured by frontal EEG leads, was recorded for each time point and change from baseline was calculated. FXS patients have typically been found to exhibit greater gamma frequency band power than typically developing controls, which may be related to social and sensory processing difficulties. Therefore, lower gamma band power would indicate better functioning.

Event-Related Potentials (ERPs) enable extraction of neural responses associated with specific sensory, cognitive, or motor events from an overall EEG. Auditory stimuli are presented and EEG events are assessed in relation to timing of the stimuli. ERP was performed at Baseline as well as at week Week 4, Week 8, Week 12, Week 16 (end of each treatment period). The area under the curve was measured for different components of the ERP including P1 and P2 (positive components) and N1 and N2 (negative components). The average area under the curve was recorded for each component at each time point and change from baseline was calculated. Individuals with FXS are thought to have excessive ERP response, so a decrease in area under each curve compared to baseline would indicate a favorable outcome.

Event-Related Potentials (ERPs) enable extraction of neural responses associated with specific sensory, cognitive, or motor events from an overall EEG. EEG data was collected when the subject was in a resting state. Frontal alpha asymmetry measures differences in alpha activity level of the right and left hemisphere of the frontal lobe of the brain. ERP was performed at Baseline as well as at Week 4, Week 8, Week 12, Week 16 (end of each treatment period). Mean alpha asymmetry at resting state was recorded and change from baseline was calculated for each time point. Higher alpha asymmetry scores indicate greater alpha power in the right hemisphere, which corresponds to increased neural activity of the left hemisphere. High activity of the left frontal lobe is hypothesized to correspond with approach behaviors, and high activity of the right frontal lobe is thought to correspond to withdrawal behaviors. In this study, higher alpha asymmetry scores indicate a better outcome.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The alertness subtest requires subjects to tap a button every time a stimulus appears on the screen. Mean reaction time was measured over 90 seconds. A lower reaction time indicates better performance.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The distractibility subtest measures how easily the subject is distracted by extraneous stimuli. This subtest requires subjects to tap a button when a target stimulus appears on the screen while ignoring distracters that appear shortly before the stimulus. A high mean number of correct responses and low mean number of errors over the 3 minutes indicates better performance.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The distractibility subtest measures how easily the subject is distracted by extraneous stimuli. This subtest requires subjects to tap a button when a target stimulus appears on the screen while ignoring distracters that appear shortly before the stimulus. A high mean number of correct responses and low mean number of errors over the 3 minutes indicates better performance.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The flexibility subtest measures the subject's ability to be flexible about shifting from one response type to another. This subtest is 2 minutes long and requires subjects to alternate between identifying blue and green dragons which seem on random sides of the screen by tapping one of two buttons. A high mean number of correct responses and low mean number of errors indicates better performance.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The flexibility subtest measures the subject's ability to be flexible about shifting from one response type to another. This subtest is 2 minutes long and requires subjects to alternate between identifying blue and green dragons which seem on random sides of the screen by tapping one of two buttons. A high mean number of correct responses and low mean number of errors indicates better performance.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The Go-NoGo subtest measures a subject's impulsivity by requiring subjects to tap a button when the target stimulus is presented, while refraining from hitting the button for the non-target stimulus. This subtest takes place over 2 minutes 30 seconds. A high mean number of correct responses and a low mean number of errors indicates better performance.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The Go-NoGo subtest measures a subject's impulsivity by requiring subjects to tap a button when the target stimulus is presented, while refraining from hitting the button for the non-target stimulus. This subtest takes place over 2 minutes 30 seconds. A high mean number of correct responses and a low mean number of errors indicates better performance.

The Clinical Global Impression-Severity (CGI-S) is a global measure to provide a clinical judgment of a participant's overall condition based on a trained clinician's assessment of cognition, behavior and activities of daily living. The clinician compares the subject with individuals of the same age and sex. The assessment of severity is with a 7-point scale: 1, not ill; 2, very mild; 3, mild; 4, moderate; 5, marked; 6, severe; 7, extremely severe.

This assessment is a parent/caregiver-rated scale with six subscales to assess irritability, stereotypes, lethargy, hyperactivity, inappropriate speech, and social avoidance, using ABC-FX factoring system. The range of possible scores are irritability (0-54), lethargy (0-39), stereotypes (0-18), hyperactivity (0-30), inappropriate speech (0-12), and social avoidance (0-12). Mean score for each subscale was calculated. Lower scores on each subscale indicate fewer aberrant behaviors (better functioning).

The ADAMS is a parent/caregiver rated scale with five sub-scores to assess manic/hyperactive behavior, depressed mood, social avoidance, general anxiety, and obsessive/compulsive behavior. The range of possible scores for each subscale is 0-21. Lower mean scores on each subscale indicate better functioning.

VABS-3 is a clinician-administered standardized interview. For this study, we collected data in domains of communication (receptive & written language), daily living skills (domestic & community skills), & socialization (interpersonal relationships, play & leisure time, & coping abilities). Mean growth scale value (GSV) for each subdomain is reported. The possible GSVs for each subdomain are receptive (10-162), written (10-163), domestic (10-110), community (10-136), interpersonal (10-152), play and leisure (10-164), & coping skills (10-120). Higher GSVs indicate better functioning.

The NIH-TCB is a battery of extensively validated computer-administered cognitive tests. The battery produces fluid and crystallized composite scores. The Total Cognition Composite Score is found by converting raw fluid and crystallized cognition scores to standard scores, averaging the these two scaled scores, then deriving standard scores based on this new distribution. Scores range from 0-140. The normative mean of the uncorrected score is 100 and the standard deviation is 15. A higher mean total cognition uncorrected composite score indicates better performance.

In an attempt to measure the level of behavioral difficulty experienced by the parent/caregiver with respect to the child with FXS, the VAS allows parents to mark on a visual line measuring 10 cm with one side marked "worst behavior" and the other side marked "best behavior." The caregiver rates the participant's behavior with respect to three domains: daily functioning, anxiety/irritability and language. Distances closer to 10 cm are considered worse behavior and distances closer to 0 cm are considered better behavior.

Event-Related Potentials (ERPs) enable extraction of neural responses associated with specific sensory, cognitive, or motor events from an overall EEG. Gamma 1 and gamma 2 waves were measured for various parts of the brain at a resting state. FXS patients have typically been found to exhibit greater gamma frequency band power than typically developing controls, which may be related to social and sensory processing difficulties. Therefore, lower gamma band power would indicate better functioning.

Event-Related Potentials (ERPs) enable extraction of neural responses associated with specific sensory, cognitive, or motor events from an overall EEG. Auditory stimuli are presented and EEG events are assessed in relation to timing of the stimuli. The area under the curve was measured for different components of the ERP including P1 and P2 (positive components) and N1 and N2 (negative components) and the average area was reported.

ERP data was collected while the subject was in a resting state. Frontal alpha asymmetry measures differences in alpha activity level of the right and left hemisphere of the frontal lobe of the brain. Higher alpha asymmetry scores indicate greater alpha power in the right hemisphere, which corresponds to increased neural activity in the left hemisphere. High activity of the left frontal lobe is hypothesized to correspond with approach behaviors, and high activity of the right frontal lobe is thought to correspond to withdrawal behaviors.

During treatment period 2, subjects will receive EM 1 mg (Medisca) and 5-HTP 100 mg (5-HTP, Basic Vitamins). One of each capsule (both size 00) will be taken three times per day for four weeks.

During treatment period 3, subjects will receive 5-HTP 100 mg (5-HTP, Basic Vitamins) and matching placebo for EM 1 mg (ascorbic acid powder). One of each capsule (both size 00) will be taken three times per day for four weeks.

During treatment period 4, subjects will receive matching placebo for EM 1mg (ascorbic acid powder) and matching placebo for 5-Hydroxytryptophan 100mg (ascorbic acid powder). One of each capsule (both size 00) will be taken three times per day for four weeks.

Adverse Events (AEs), including clinically meaningful laboratory abnormalities and significant behavioral changes will be tabulated for each treatment period.

The Investigator is responsible for assessing the severity (intensity) of each adverse event as mild, moderate, or severe according to the following definitions:

Mild - An event that is easily tolerated and generally not interfering with normal daily activities. Moderate - An event that is sufficiently discomforting to interfere with normal daily activities. Severe - An event that is incapacitating with inability to work or perform normal daily activities.

The Safety population will include all participants who received at least one dose of study treatment.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The alertness subtest requires subjects to tap a button every time a stimulus appears on the screen. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean reaction time was measured over 90 seconds and change from baseline was calculated. A lower reaction time (net decrease in reaction time) indicates better performance.

Intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The distractibility subtest measures how easily the subject is distracted by extraneous stimuli. This subtest requires subjects to tap a button when a target stimulus appears on the screen while ignoring distracters that appear shortly before the stimulus. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean number of correct responses and errors were recorded, and change from baseline was calculated. For the distractability subtest, a higher mean number of correct responses and lower mean number of errors over the 3 minutes indicates better performance.

Intent to treat (ITT) efficacy population, which includes all participants who received at least one dose of treatment and returned for at least one follow-up visit.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The distractibility subtest measures how easily the subject is distracted by extraneous stimuli. This subtest requires subjects to tap a button when a target stimulus appears on the screen while ignoring distracters that appear shortly before the stimulus. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean number of correct responses and errors were recorded, and change from baseline was calculated. For the distractability subtest, a higher mean number of correct responses and lower mean number of errors over the 3 minutes indicates better performance.

Intent to treat (ITT) efficacy population, which includes all participants who received at least one dose of treatment and returned for at least one follow-up visit.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The flexibility subtest measures the subject's ability to be flexible about shifting from one response type to another. This subtest is 2 minutes long and requires subjects to alternate between identifying blue and green dragons which seem on random sides of the screen by tapping one of two buttons. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean number of correct responses and errors were recorded and change from baseline was calculated. For the flexibility subtest, a higher mean number of correct responses and lower mean number of errors indicates better performance.

Intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The flexibility subtest measures the subject's ability to be flexible about shifting from one response type to another. This subtest is 2 minutes long and requires subjects to alternate between identifying blue and green dragons which seem on random sides of the screen by tapping one of two buttons. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean number of correct responses and errors were recorded and change from baseline was calculated. For the flexibility subtest, a higher mean number of correct responses and lower mean number of errors indicates better performance.

Intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The Go-NoGo subtest measures a subject's impulsivity by requiring subjects to tap a button when the target stimulus is presented, while refraining from hitting the button for the non-target stimulus. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). This subtest takes place over 2 minutes 30 seconds. Mean number of correct responses and errors were recorded, and change from baseline was calculated. For the Go-NoGo subtest, a higher mean number of correct responses and a lower mean number of errors indicates better performance.

The primary efficacy population will be the intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

The KiTAP is a computerized executive function battery that consists of eight nonverbal subtests measuring different basal as well as higher-order components of attention and executive functioning. The Go-NoGo subtest measures a subject's impulsivity by requiring subjects to tap a button when the target stimulus is presented, while refraining from hitting the button for the non-target stimulus. KiTAP was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). This subtest takes place over 2 minutes 30 seconds. Mean number of correct responses and errors were recorded, and change from baseline was calculated. For the Go-NoGo subtest, a higher mean number of correct responses and a lower mean number of errors indicates better performance.

The primary efficacy population will be the intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

The Clinical Global Impression-Severity (CGI-S) is a global measure to provide a clinical judgment of a participant's overall condition based on a trained clinician's assessment of cognition, behavior and activities of daily living. The clinician compares the subject with individuals of the same age and sex. The assessment of severity is with a 7-point scale: 1, not ill; 2, very mild; 3, mild; 4, moderate; 5, marked; 6, severe; 7, extremely severe. A net decrease in severity score over time indicates a positive outcome.

Intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

This assessment is a parent/caregiver-rated scale with six subscales to assess irritability, stereotypes, lethargy, hyperactivity, inappropriate speech, and social avoidance, using ABC-FX factoring system. The ABC was was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean score for each subscale was measured and change from baseline was calculated. Lower mean scores on each subscale indicate fewer aberrant behaviors (better functioning).The range of possible scores on each subscale are irritability (0-54), lethargy (0-39), stereotypes (0-18), hyperactivity (0-30), inappropriate speech (0-12), and social avoidance (0-12).

Intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

The ADAMS is a parent/caregiver rated scale with five subscores to assess manic/hyperactive behavior, depressed mood, social avoidance, general anxiety, and obsessive/compulsive behavior. The ADAMs was completed at Baseline as well as Week 4, Week 8, Week 12, and Week 16 (the end of each treatment period). Mean score for each subscale was recorded, and change from baseline was calculated for each subscore. The range of possible scores for each subscale is 0-21. Lower mean scores on each subscale indicate better functioning.

Intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

VABS-3 is a clinician-administered standardized interview. For this study, we collected data in domains of communication (receptive & written language), daily living skills (domestic & community skills), & socialization (interpersonal relationships, play & leisure time, & coping abilities). This assessment was administered at Baseline as well as at Week 4, Week 8, Week 12, and Week 16 (end of each treatment period). Mean growth scale value (GSV) for each subdomain was recorded at each time point and change from baseline was calculated. The possible GSVs for each subdomain are receptive (10-162), written (10-163), domestic (10-110), community (10-136), interpersonal (10-152), play and leisure (10-164), & coping skills (10-120). Higher GSVs for each subdomain indicate better functioning.

Intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

The NIH-TCB is a battery of extensively validated computer-administered cognitive tests. The NIH-TCB includes 7 evaluations measuring cognitive flexibility, inhibition & visual attention, episodic memory, immediate recall & sequencing of different visually & orally presented stimuli, processing speed, recognition of letters and words, & receptive vocabulary. This assessment was administered at Baseline as well as at Week 4, Week 8, Week 12, and Week 16 (end of each treatment period). This battery produces fluid and crystallized cognition composite scores. The Total Cognition Composite Score is found by converting raw fluid and crystallized scores to standard scores, averaging these two scores, then deriving standard scores based on this new distribution. Scores range from 0-140. The normative mean of the uncorrected standard score is 100 and the standard deviation is 15. A higher mean total cognition composite score indicates better performance.

Intent to treat (ITT) efficacy population, which includes all participants who received at least one dose of treatment and returned for at least one follow-up visit.

IIn an attempt to measure the level of behavioral difficulty experienced by the parent/caregiver with respect to the child with FXS, the VAS allows parents to mark on a visual line measuring 10 cm with one side marked "worst behavior" and the other side marked "best behavior." The caregiver rated the participant's behavior with respect to three domains: daily functioning, anxiety/irritability and language. Distances closer to 10 cm are considered worse behavior and distances closer to 0 cm are considered better behavior. Average distance of the mark was recorded for each domain at Baseline then again at Week 4, Week 8, Week 12, and Week 16 (end of each treatment period). Change from baseline was calculated for each domain. Lower scores indicate a better outcome (closer distance to best behavior side).

Intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

Event-Related Potentials (ERPs) enable extraction of neural responses associated with specific sensory, cognitive, or motor events from an overall EEG. Gamma 1 and gamma 2 waves were measured for various parts of the brain at a resting state. ERP was performed at Baseline as well as at Week 4, Week 8, Week 12, Week 16 (at the end of each treatment period). Mean power of gamma 1 and gamma 2 bands, measured by frontal EEG leads, was recorded for each time point and change from baseline was calculated. FXS patients have typically been found to exhibit greater gamma frequency band power than typically developing controls, which may be related to social and sensory processing difficulties. Therefore, lower gamma band power would indicate better functioning.

Intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

Event-Related Potentials (ERPs) enable extraction of neural responses associated with specific sensory, cognitive, or motor events from an overall EEG. Auditory stimuli are presented and EEG events are assessed in relation to timing of the stimuli. ERP was performed at Baseline as well as at week Week 4, Week 8, Week 12, Week 16 (end of each treatment period). The area under the curve was measured for different components of the ERP including P1 and P2 (positive components) and N1 and N2 (negative components). The average area under the curve was recorded for each component at each time point and change from baseline was calculated. Individuals with FXS are thought to have excessive ERP response, so a decrease in area under each curve compared to baseline would indicate a favorable outcome.

Intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

Event-Related Potentials (ERPs) enable extraction of neural responses associated with specific sensory, cognitive, or motor events from an overall EEG. EEG data was collected when the subject was in a resting state. Frontal alpha asymmetry measures differences in alpha activity level of the right and left hemisphere of the frontal lobe of the brain. ERP was performed at Baseline as well as at Week 4, Week 8, Week 12, Week 16 (end of each treatment period). Mean alpha asymmetry at resting state was recorded and change from baseline was calculated for each time point. Higher alpha asymmetry scores indicate greater alpha power in the right hemisphere, which corresponds to increased neural activity of the left hemisphere. High activity of the left frontal lobe is hypothesized to correspond with approach behaviors, and high activity of the right frontal lobe is thought to correspond to withdrawal behaviors. In this study, higher alpha asymmetry scores indicate a better outcome.

Intent to treat (ITT) efficacy population, which will include all participants who received at least one dose of treatment and returned for at least one follow-up visit.

2 placebo capsules three times daily for 4 weeks

Placebo: Placebo capsules

Ergoloid mesylates (EM) 1 mg three times daily and 1 placebo capsule three times daily for 4 weeks.

Ergoloid Mesylate: Ergoloid Mesylates, trade name Hydergine, is a mixture of the methanesulfonate salts of three dihydrogenated ergot alkaloids, dihydroergocristine, dihydroergocornine, and alpha- and beta-dihydroergocryptine. Ergot alkaloids are dopamine agonists which activate dopamine receptors (in the basal ganglia and other parts of the brain involved in motor function) and a prolactin inhibitor. Ergot is a strong vasoconstrictor and thus helps to reduce bleeding by narrowing of the blood vessels.

Placebo: Placebo capsules

5-hydroxytryptophan (5-HTP) 100 mg three times daily and 1 placebo capsule three times daily for 4 weeks.

5-Hydroxytryptophan / Vitamin B6: 5-hydroxytryptophan, also known as 5-HTP has a nutraceutical status and has never been approved as a drug for any indication, but as a dietary supplement has been used extensively for several disorders for many years such as in the therapy of depression, fibromyalgia, obesity, insomnia and chronic headache

Placebo: Placebo capsules