Zip code, date of birth, sex, race, and primary language were all caregiver-reported demographic fields collected at the time of the individual’s registration into the EMR.

A “General Development” form, which was developed by the DSP team (Baumer et al., 2022), was given to children of all ages. For those older than age three years, a standardized caregiver-completed developmental monitoring tool, the Neurodevelopmental Parent Report for Outcome Monitoring (formerly the Autism Spectrum Disorder Parent Report for Outcome Monitoring; ASD-PROM) was also given. In its entirety, the ND-PROM consists of 127 Likert-scale style questions that assess general development and maladaptive behaviors, including communication, social skills, behavioral functioning, and adaptive skills (Levin et al., 2021). Seventeen of these questions, relevant to development, were selected for inclusion in this project (Table 1). Caregivers indicated “never,” “rarely,” “sometimes,” “often,” or “always” to each question. Skills were determined as “established” when caregivers responded that an individual was “often” or “always” doing the skill. Though initially used in autism spectrum disorder (ASD), the ND-PROM covers domains relevant for individuals with other developmental disabilities and neurodevelopmental conditions (Baumer et al., 2024).

Information about behavior was derived from two sources for children ages three and older. First, the presence of behavioral concerns was defined as a report of “often” or “always” to the following items on the ND-PROM: Repetitive Movements; Repetitive Activities; Difficulties with Transition; Aggression Toward Self; Aggression Toward Others; and Running Away (e.g., bolting or wandering). Second, a caregiver form created by the DSP team (Baumer et al., 2022) that was presented to all patient families at the time of their visit to the DSP asked caregivers to report their most salient concerns at the visit (“Caregiver’s Chief Clinical Concerns”). The caregiver-reported behavioral information includes concerns at the time of a clinic visit and captures specific behavioral concerns, whereas the ND-PROM captures ongoing frequency of specific maladaptive behaviors (not specifically caregiver concerns), which was binarily coded as behavioral concern or no behavioral concern.

Families were asked to complete an “Education and Services” form, which was also developed by the DSP team (Baumer et al., 2022) to share information about service receipt and activity participation across several domains: receipt of developmental and behavioral services (i.e., EI; as well as Behavioral Therapy, Occupational Therapy, Physical Therapy, and Speech Therapy received outside of EI or school); educational classroom placement (i.e., Inclusion setting, which is when a child is integrated into the general education classroom; Partial Inclusion setting, which is when a child is integrated into the general education classroom for some of the school day; and Substantially Separate setting, which is when a child is in a low teacher-to-student ratio environment rather than the general education classroom); Recreational Activities, which included physical activity/exercise (e.g., non-therapy sports teams), social activities (e.g., spending time with friends), religious activities (e.g., attending services), and non-school group activities; Family Services, which included supports such as case management, counseling, legal/financial services, and educational advocates; and barriers to services at the time of their clinical visits. Possible barriers included Insurance Coverage/Finances, Provider Availability, Transportation, and Lack of Necessary Information About How to Access Services.

Expressive language skills were still emerging before age three years (Uses >50 Words/Signs/Phrases: 10%; Uses 3–4 Word Sentences: 5%), and very few used Picture Communication (2%). Many achieved Walking Independently (44%) and Following 1-Step Directions (39%), and about a third Pointed to Request (29%).

By age five, about half of children Used >50 Words/Signs/Phrases (44%). Most communicated with Spoken Language (69%) and some used Sign Language (23%). Nearly two-thirds of three-to five-year-olds demonstrated Simple Pretend Play actions (65%) and more children were beginning to brush their teeth (“Brushes Teeth”; 41%). Almost all children were Walking Independently (90%) and over half were Running (52%).

Nearly two-thirds of children Used >50 Words/Signs/Phrases (65%) by age seven years and about a half Used 3–4 Word Sentences (48%). Spoken Language was used most frequently (83%). More independent adaptive skills also began to emerge between ages five and seven years; for example, over a quarter dressed themselves (“Dresses Self”; 29%) and over half brushed their teeth (“Brushes Teeth”; 51%). Half were Toilet Trained (51%) and Counted At Least 5 Objects (51%).

Between ages seven and 10 years, most children Used 3–4 Word Sentences (65%), relying on Spoken Language (84%) to communicate. A small number (4%) Did Not Communicate using any verbal or nonverbal communication modality. Adaptive skills continued to establish: some brushed their teeth (“Brushes Teeth”; 38%) and dressed themselves (“Dresses Self”; 49%), and most were Toilet Trained (70%). With regard to academic skills, many Counted At Least 5 Objects (70%), Read At Least 10 Words (46%), and wrote their name (“Writes Name”; 51%). Some Knew Basic Addition (17%) and Basic Subtraction (11%).

Expressive language skills and adaptive skills were well established by fourteen years of age in most children. Almost all used Spoken Language (89%), with fewer using alternative communication strategies. A very small number Did Not Communicate (2%). Academically, the majority of children Counted At Least 5 Objects (77%), Read At Least 10 Words (62%), and wrote their name (“Writes Name”; 51%) by age fourteen years. Some Knew Basic Addition (39%) and Basic Subtraction (31%). Between ages 14 and 18 years, similar patterns were noted.

The majority of children below three years of age (91%) received EI services, and many (53%) received Speech Therapy through EI. Some attended Daycare (23%). Very few children under three years of age received Behavioral Therapy through EI (3%). Almost no one reported receiving Behavioral Therapy outside of EI (1%). While many families received Services (87%), some encountered barriers, such as lack of Provider Availability (42%) and Necessary Information About How to Access Services (32%). Over half of children participated in Recreational Activities (55%).

Most children of this group were in an Inclusion setting (61%), while fewer participated in Partial Inclusion (20%) or Substantially Separate (20%) classrooms (i.e., attending a small teacher-to-student ratio classroom specific for special education needs). Many children received services outside of their school system, including Speech and Language Therapy (64%), Physical Therapy (38%), and Occupational Therapy (40%). Hardly any children received Behavioral Therapy outside of school (1%). The majority of families received Services (80%), while some encountered barriers (19%). Over three quarters of children participated in Recreational Activities (78%).

In this age group, some were taught in an Inclusion classroom (55%), while others attended a Partial Inclusion (23%), and/or Substantially Separate classroom (22%). Services were commonly received outside of school (Speech and Language Therapy: 61%; Physical Therapy: 31%; Occupational Therapy: 40%). Some five-to seven-year-olds also accessed Behavioral Therapy outside of school (14%). Most families received Services (78%), while some encountered barriers (12%). The majority of children participated in Recreational Activities (78%).

Between the ages of seven and ten, many (42%) were in a Partial Inclusion classroom setting, with fewer in an Inclusion classroom (30%) or Substantially Separate classroom (28%). Non-school services were frequently received (Speech and Language Therapy: 61%; Physical Therapy: 33%; Occupational Therapy: 42%). Behavioral Therapy was received by some outside of school (21%). Most families received Services (74%), and many encountered barriers to services (18%). The vast majority of children were involved in Recreational Activities (81%).

Only some of ten-to fourteen-year-olds were in an Inclusion classroom (15%), with most placed in either a Partial Inclusion classroom (45%) or Substantially-Separate classroom (39%). Many received Speech and Language Therapy (40%) and others accessed Physical (21%) and Occupational Therapy (28%) outside of school. Some received Behavioral Therapy outside of school (23%). About a third (32%) faced barriers. Almost all were involved in Recreational Activities (85%).

In this age group, most children were placed in a Substantially-Separate classroom (62%), while fewer remained in a Partial Inclusion (29%) or Inclusion classroom (9%). Some received non-school Speech and Language Therapy (34%) and a quarter received private Occupational Therapy (25%). Only a few received Physical Therapy (15%) and Behavioral Therapy (21%) outside of school. It was common for families to face barriers (31%). Almost all were involved in Recreational Activities (90%).

The study serves as a snapshot of development and services received by a large number of patients in a relatively high resourced area; thus, our cohort is not representative of the broader population of the United States and the generalizability of the results is limited. As such, the results of this study may reflect developmental changes in those with DS who receive more support through EI and special needs education compared to other populations. Additionally, given that the individuals in this study are followed in the clinic until they transition to adult services, it is possible that many choose to continue to receive care in the clinic because they have complex needs, which may influence development, behavior, and services reported. Secondly, though the database involved standardizing clinical practice across several providers of different training backgrounds, it did not exclusively involve the use of standardized data collection tools. Given the approach of collecting information in all clinic visits, there are variations in the number of individuals who completed each of the measures. Third, caregiver report of services may be misrepresented in some areas. For example, caregivers may have misread or misunderstood sections of forms and noted non-public services instead of EI or school programming services. Fourth, because we reviewed collected data on milestones at the time of each clinical visit, the exact timing of milestone achievement was not available. Additionally, the data were collected prior, during, and after the COVID-19 pandemic, but did not specifically look at types of services that continued or discontinued during the COVID-19 timeframe. Finally, the expertise of the clinicians in areas like toileting and educational supports may draw families who are in greater need of those services.

Future studies should investigate correlations between development and services in this population, and should extend across all ages, including adults. Further investigation into the potential confounding impacts and relationships of certain developmental domains (e.g., the attainment of gross motor milestones) on cognitive and academic skills must be explored (Will et al., 2018). It is also important to consider the impact of social isolation and the interruption of services during the COVID-19 pandemic period.