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Chapter 4 Cognitive Difficulties in Children with Type 1 Diabetes

Clarissa S. Holmes, PhD

Research into the cognitive status of youth with diabetes has grown over the last quarter of a century and increased in sophistication. Incorporation of neuroimaging techniques allows better understanding of physiological correlates and substrates of emerging cognitive patterns. Discussion of neuroimaging results is beyond the scope of this chapter but the reader is referred to several recent reviews (Musen 2008a, Holmes 2010). Despite these scholarly gains in understanding the relation between diabetes and cognitive status in youth, familial differences and demographic factors, such as social class status, still remain primary factors that account for significant individual differences in cognition, consistent with results from the general population (Overstreet 1997a, Sattler 2001).

Intellectual Performance

Children with type 1 diabetes (T1D) generally have average or above average intellectual functioning (intelligence quotient [IQ] >85). With an average score of 100 and a standard deviation of 15, individual and family differences in IQ exist, similar to those in the general population (Overstreet 1997a, Northam 2001, Gaudieri 2008). Although overall IQ scores of children with T1D are in the average range, they are slightly lower, by ~3 points, than scores of children without diabetes. A group difference of this magnitude has little clinical significance, although it is of scientific interest.

The Wechsler scales are the most commonly used ability tests in school systems. Different versions are available: for young children <7 years old, the Wechsler Intelligence Scale for Preschoolers (WPPSI-III) (Wechsler 2002); for school-age youth 6–16 years old, the Wechsler Intelligence Scale for Children–IV (WISC-IV) (Wechsler 2003); and for older adolescents over age 16 years, the Wechsler Adult Intelligence Scale (WAIS-IV) (Wechsler 2008). Other scales are available but are less commonly in use, such as the Kaufman Assessment Battery for Children–Second Edition (K-ABC–II) (Kaufman 2004) and the Differential Ability Scales–Second Edition (DAS-II) (Elliot 2007).

Learning Disorders

For most children with diabetes, academic achievement is at grade level (McCarthy 2002) or consistent with IQ (Overstreet 1997b). However, ~5% of children in the general population experience learning disorders in reading, mathematics, or written language with achievement that is substantially below expectation for age, schooling, and level of intelligence (American Psychiatric Association [APA] 2000). Some children with diabetes, especially those with disease risk factors, may show a higher incidence of learning problems (Holmes 1992, Lin 2010).

Assessment of Achievement and Learning Disorders

Diagnostic criteria for learning disorders vary by local educational/school districts. However, the national Diagnostic and Statistical Manual of Mental Disorders IV (DSM IV) criteria of the APA (2000) include the following: average intelligence with academic achievement substantially below IQ, age, or schooling. Often evidence of cognitive “processing” or neuropsychological difficulties (i.e., attention, memory, learning processing problems) is present. A broad survey of skills in language, executive function/planning and attention, visual spatial functioning, memory and learning, and sensorimotor skills is commonly assessed with A Developmental Neuropsychological Assessment–Second Edition (NEPSY-II) (Korkman 2007). Specialized measures of processing skills such as memory can be assessed with the Wechsler Memory Scale–Third Edition (WMS-III) (Wechsler 1997), the Wide Range Assessment of Memory and Learning–Second Edition (WRAML-II) (Sheslow 2003), and the Children’s Memory Scale (CMS) (Cohen 1997). Often these more specialized neuropsychological tests are administered by referral only to a specially trained neuropsychologist outside of the school system. Criteria for special classroom assistance typically require a “clinical threshold” to be reached, usually performance on individually administered achievement tests that is 15 or more points (1–2 standard deviations) below expectation for IQ (APA 2000). Widely used achievement tests available in most school systems include the Woodcock Johnson Tests of Achievement (WJ-III-ACH) (Woodcock 2001), the Wide Range Achievement Test–Fourth Edition (WRAT-4) (Wilkinson 2006), and the Wechsler Individual Achievement Test–Third Edition (WIAT-III) (Wechsler 2009). Like IQ tests, these measures typically provide standardized scores with an average score of 100 and a standard deviation of 15. For most children with diabetes, learning disorders are likely to be ”subclinical” and below the level of severity required for formal diagnosis (APA 2000). Medical insurance often covers the cost of psychoeducational assessment administered by qualified personnel. Local school psychologists provide another cost-free option, although this latter option may entail a long wait for services. Finally, parents may be referred to a licensed private psychologist or a clinic-based psychologist such as in a mental health agency. Reevaluation of learning status is required every three years for children formally diagnosed with learning disorders.

Remedial Services

Studies from the early 1990s document a higher incidence of academic classroom assistance for children with diabetes (Hagan 1990, Holmes 1992). Medical management recommendations were modified for younger children, particularly those under the age of 5 years (Ryan 1985, Rovet 1988) to avoid episodes of severe hypoglycemia that lead to seizures or unconsciousness (Silverstein 2005). In the last 10 years there have been few or conflicting studies of the incidence of specialized classroom assistance in diabetic youth (Crawford 1995). Thus, earlier studies may no longer accurately reflect the current incidence of special classroom placement.

The Education of All Handicapped Children Act of 1974 (PL 94-142), now called the Individuals with Disabilities Education Act (IDEA), mandates that all states provide a free appropriate public education (FAPE) in the least restrictive environment for children with a handicapping condition, such as special educational or learning needs, to receive federal funds. Services may be mandated based on borderline or lower intellectual abilities or a significant discrepancy between an individually administered IQ score and an achievement test score along with cognitive processing difficulties, such as clinically significant memory problems. If an individual meets these criteria, services may be provided and an Individual Education Plan (IEP) formulated. An IEP documents the special services or accommodations to be provided for a child in the classroom. Only children with diabetes who have a clinically diagnosable learning disability will qualify for these intensive school services. More information about IDEA is available at www.ed.gov/offices/OSERS/OSEP or through the American Diabetes Association (ADA) at http://www.diabetes.org/living-with-diabetes/parents-and-kids/diabetes-care-at-school/written-care-plans.

Most children with diabetes qualify for a broader, less intensive range of educational services or accommodations through the Education Rehabilitation Act of 1973. This Act forbids discrimination against individuals on the basis of a “disability,” which can include temporary disabilities such as a broken leg. Under Section 504 of the Act, students with medical conditions can receive accommodations to participate in academic and extracurricular activities the same as other students. Diagnosis with a formal learning disability is not required to receive educational accommodations with a 504 Plan. Often the foundation of a 504 Plan is a Diabetes Medical Management Plan (DMMP) or physician’s order that prescribes recommended school-based medical care plans. The DMMP is the medical basis for an Individualized Health Plan (IHP), written by the school nurse, which specifies what, where, when, and by whom diabetes care tasks will be provided in school. The IHP provides medical care at school but not educational accommodations. A diabetes 504 Plan provides written guidelines for diabetes-related educational accommodations that are protected under federal law. Common services and exceptions may include storing and administering insulin and blood glucose monitoring equipment or supplies at school as well as allowing students to carry and eat snacks in the classroom. More frequent school absences are permitted to accommodate routine medical visits, and extra bathroom breaks or trips to the water fountain are usually allowed. Private schools that receive federal funds must also be responsive to these student-related requests. A teacher, psychologist, school nurse, or principal can organize a 504 meeting. Before a meeting, parents can write a letter that explains their child’s diabetes-related needs and how they can be accommodated in school. If necessary, a physician can write a letter to explain unusual medical needs. More information is available about 504 Plans at http://www.isbe.net/spec-ed/pdfs/parent_guide/ch15-section_504.pdf or via the American Diabetes Association at http://www.diabetes.org/living-with-diabetes/parents-and-kids/diabetes-care-at-school/written-care-plans.

Neuropsychological Skills Associated with Learning Problems

Despite generally average IQ scores, subgroups of children may have a higher risk for specific cognitive processing problems or neuropsychological difficulties, in areas such as visual spatial or memory skills. Clinically significant difficulties are defined as more than 15 points below intellectual level (1–2 standard deviations). The following difficulties have been described in subgroups of children with diabetes; individuals may or may not be affected.

Chronic Disease–Related Findings

Earlier disease onset, defined by some authors as <5 years and by others as <7 years, is related to greatest skill disruption, compared with other groups of diabetic children, with lowest scores (4 to 6 points) in mental processing speed, verbal memory, and learning. Differences of this magnitude could be clinically detectable in school performance and may be perceived by children as frustrating and as relative weaknesses compared with their other stronger skills. Slightly lower (2 to 3 points) nonverbal/visual spatial skills, visual memory and learning, and academic achievement are found in children with later disease onset (Ryan 1985, Rovet 1990, Northam 2001, Gaudieri 2008). However, these differences may become greater, up to 7 points, with longer disease duration in adults who had early disease onset (Ferguson 2005).

Longer disease duration, defined as greater than 5 years but usually less than 8 or 9 years in pediatric populations, is related to mildly lower spatial and visual/perceptual skills (2 to 3 points), compared with shorter disease duration under 5 years. Cross-sectional and longitudinal studies indicate that lower verbal memory and failure to make expected developmental gains in vocabulary and other areas of verbal school achievement may be detectable as soon as 2 years after diagnosis with diabetes (Ryan 1985, Rovet 1990, Northam 2001).

Recurrent Severe Hypoglycemia and Chronic Hyperglycemia

Severe hypoglycemia that results in seizures or unconsciousness may have differential age-related effects on the brain, with greater visual spatial and diffuse brain and skill impact on children below the age of 5 or 6 years (Hannonen 2003, Hershey 2003). For older children, controversy exists regarding whether severe hypoglycemia affects verbal memory and, if so, at what glycemic threshold. Clinically, detrimental lasting effects may be seen only with multiple severe hypoglycemic episodes (i.e., over five) or episodes that may interact with a sensitive period of child brain development (i.e., under age 5). At the other end of the glucose continuum, recurrent/protracted hyperglycemia or poorer metabolic control (defined by elevated glycosylated hemoglobin levels >9.0%) is associated with significantly lower general and verbal intellectual ability (7 points) compared with those in better metabolic control (Kaufman 1999, Lynch 2006, Perantie 2008). Significantly poorer visual and verbal learning is found compared with children in better metabolic control (Greer 1996, Lynch 2006), along with significant academic underachievement. In preschool children, protracted hyperglycemia, reflected in higher A1C levels, relates to lower general cognitive ability, poorer receptive language scores, and slower fine motor speed (Patino-Fernandez 2010). In older elementary school–age children, chronic poorer metabolic control has been found to relate to lower academic achievement and poorer attention/memory (Kaufman 1999). Poorer metabolic control may interact with each of the previous disease risk factors and amplify effects.

Acute Disease–Related Findings

Beyond these generally chronic cognitive effects (Gaudieri 2008, Bade-White 2009), evidence of acute, transient cognitive disruption is associated with some diabetes conditions. Acute mild hypoglycemia, defined as >50 mg/dl and <90 mg/dl, is related to transient slowing/disruption in higher-ordered executive functioning (attention, planning, complex decision making) as well as slowed verbal fluency, memory, and motor speed. Accuracy is usually intact (Reich 1990, Ryan 1990, Gonder-Frederick 2009). In the classroom, a hypoglycemic child will have trouble attending to and encoding new information to be recalled. The child may appear sleepy or lethargic. Speed of responding and other cognitive function may not return to normal (prehypoglycemic) levels for up to 45 min once euglycemia is achieved. Despite disrupted blood glucose levels, no evidence of increased rates of attention deficit hyperactivity disorder is reported in association with diabetes. Clinically, attention problems that occur with mild transient hypoglycemia are consistent with the inattentive subtype of attention deficit disorder (Bade-White 2009), although the condition should not be diagnosed if it is secondary to hypoglycemia, i.e., an underlying medical problem. The diagnosis of inattention subtype due to attention deficit disorder would be accurate in the absence of fluctuations in blood glucose, particularly hypoglycemia. Acute transient hypoglycemia that involves seizures or unconsciousness is “severe” and falls under the guidelines for severe recurrent hypoglycemia.

In contrast to hypoglycemia, acute hyperglycemia, defined as a blood glucose level of >300 mg/dl, is relatively unstudied in children, but initial evidence shows an association with slightly lower verbal memory and vocabulary scores as well as reduced speed of cognitive functioning, similar to the effects of acute hypoglycemia (Gonder-Frederick 2009).

Assessment of Neuropsychological Status

Evaluation of neuropsychological status and associated academic performance should follow generally accepted guidelines for identifying children in need of academic assistance. Specialty tests in memory and other neuropsychological skills are available (Lezak 2001). Although tests can be administered by any licensed psychological practitioner, interpretation of results will be more accurate when provided by a trained neuropsychologist or specialist who works with children who have diabetes. Neuropsychological difficulties often co-occur with learning disorders in specific academic areas such as reading or mathematics. State and federal guidelines mandate formal recertification or reassessment of youth diagnosed with learning disorders every three years (Education Rehabilitation Act of 1973). Adoption of testing guidelines also is appropriate with subclinical learning problems. Generally, if a child has learning difficulties of a magnitude that impedes daily or classroom functioning, the youth should be referred to a pediatric or child psychologist. This recommendation includes children who consistently underachieve in a school subject or who have difficulty with memory or other cognitive processing skills. A teacher or parent referral for a psychoeducational screening can help determine the cause of the problem. A screening test of reading, math, and written skills can be administered by an educational specialist. If a problem is found, follow-up comprehensive testing is necessary to qualify for assistive school services. Medical insurance often covers the cost of psychoeducational assessment administered by qualified personnel. Local school psychologists provide another cost-free option, although this latter choice may entail a longer wait for services.

Assessment Considerations

For children with diabetes it is important to first rule out or otherwise address more common medically related issues of school absences, poorer glycemic control, and glucose fluctuations in the classroom, all of which may relate to lower academic achievement as well as memory and attention problems.

During psychological assessment, psychologists should first make sure a child is able to perform blood glucose tests and treat episodes of hypoglycemia. A child should bring a glucose meter to the assessment session, ideally along with a small snack of juice and crackers, in case they should be needed. Glucose testing should occur immediately before psychological testing is begun to maximize optimal performance. Even mild hypoglycemia (blood glucose level >60 and <90 mg/dl) can adversely impact psychological test performance and scores. If moderate or severe hypoglycemia (blood glucose level ≤50 mg/dl) is detected, psychological testing should be rescheduled for another day to allow time for recovery of optimal cognitive status. However, steps should be taken if mild hypoglycemia is suspected during psychological assessment. The assessment should be paused, a blood check should be performed by the child with the child’s own equipment, and a snack should be consumed by the child. Packets of peanut butter crackers and juice boxes provide a good supplement to a test kit. After ingestion of 15 grams of carbohydrate and a 15-min wait, a child should retest his or her blood glucose level to confirm euglycemia, and psychological testing can proceed.

Treatment of Learning Disorders

Treatment recommendations for learning disorders should be selected with consideration of a child’s underlying cognitive strengths and weaknesses as well as the affected academic area. Traditionally, learning problems, if present, may be handled either with remediation strategies that promote acquisition of delayed skills (deficit-focused) or with compensation strategies that focus on residual abilities and environmental strategies to facilitate optimal skill use (strength-focused) (Kanne 2010). Often a combination of techniques is utilized, but most of the treatment literature has studied individuals with frank neurologic difficulty (Raskin 2010) typically not seen in youth with diabetes. Although these strategies reflect current thinking (Kanne 2010, Raskin 2010), they lack empirical validation of treatment efficacy. Currently no studies exist with youth who have diabetes. Thus recommendations for remediation are based on general recommendations for children with learning disorders.

Recommendations for Intervention

1. Circumvention of the problem. Clinical experience suggests that it is better to teach to “strengths” rather than to drill to remediate “weaknesses.” For example, spatial weaknesses can be minimized by giving oral directions rather than a written or drawn map or by adoption of a phonetic versus sight word reading approach.

2. Assistive learning devices. Dependent upon the problem, use of assistive learning devices can be helpful. For example, for isolated memory problems, use of a calculator can help compensate for memory difficulty with math facts and provide an opportunity for practice and recognition learning.

3. Reduced psychomotor efficiency could necessitate untimed or supplemental time allowances on tests.

4. Avoid stigmatization of children. All individuals have cognitive strengths and weaknesses; the peaks and valleys simply may be a little farther apart for a small percentage of children with diabetes who have diagnosable or subclinical learning disorders.

5. Help the child, family, and academic providers to understand differences between transient cognitive deficits associated with fluctuations in glucose and diagnosed learning differences.

6. Self-esteem difficulties may be present. If they are persistent or severe, psychological treatment should be sought with a school counselor or trained therapist to reassure a child of his or her strengths and to place relative weaknesses in perspective. Children with diabetes are already coping with an altered sense of self because of their illness, which could increase vulnerability to low sense of self-worth (see Chapter 14).

Prevention or Minimization of Cognitive Difficulties

The majority of youth with diabetes do not have learning problems that rise to the level of clinical or subclinical learning disorders. However, transient disruption of memory/attention or slowed psychomotor efficiency could occur relatively routinely in the classroom in conjunction with temporary changes in blood glucose concentrations. Subsequent frustration could impede academic performance. Long-term longitudinal study suggests youth with diabetes have higher dropout rates in secondary school compared with nondiabetic counterparts (Lin 2010), a finding that merits replication.