Medication Summary
No specific pharmacologic treatment is available for cognitive impairment in the developing child or adult with MR/ID.[28] Medications, when prescribed, are targeted to specific comorbid psychiatric disease or behavioral disturbances.
Development of nootropic drugs that may alter cognitive processes positively has been of interest to researchers. Medications currently prescribed for dementia, such as acetylcholinesterase inhibitors, are not accepted treatments for MR/ID, and clinical trials have not been conducted in children. Phosphodiesterase inhibitors enhance cortical plasticity in an animal model of fetal alcohol syndrome.
Although vitamin and mineral therapies have gained popularity, their efficacy has not been established in clinical trials. A randomized controlled study of antioxidants and/or folinic acid for 18 months in 156 infants with Down syndrome found no evidence to support the use of these supplements in this population.[29]
CNS stimulants
Class Summary
The most common class of drugs prescribed in this population is the psychostimulants because of the coexistence of attention deficit with or without hyperactivity disorder (ADHD/ADD) in as many as 50%. The most widely used psychostimulants are methylphenidate and dextroamphetamine, which appear to enhance dopamine and norepinephrine activity in the CNS.
Methylphenidate hydrochloride (Ritalin, Metadate ER)
Stimulates cerebral cortex and subcortical structures.
Dextroamphetamine sulfate (Dexedrine) and racemic amphetamine (Adderall)
Increase amount of circulating dopamine and norepinephrine in cerebral cortex by blocking reuptake of norepinephrine or dopamine from synapse.
Alpha-adrenergic agonists
Class Summary
These agents are used commonly to modulate hyperactivity, aggression, tics, and dyssomnias.
Clonidine hydrochloride (Catapres)
Agonist at presynaptic alpha2-adrenergic receptors within brain stem. Clonidine reduces norepinephrine release at these sites, reducing sympathetic outflow and enhancing parasympathetic outflow. May reduce aggression by increasing release of GABA in frontal cortex and other brain regions.
Guanfacine (Tenex)
Presynaptic alpha2-adrenergic receptor agonist that stimulates alpha2-adrenergic receptors in brain stem, activating an inhibitory neuron, which in turn decreases vasomotor tone and heart rate. Similar reduction in potentially negative impact on academic performance and cognitive function.
Neuroleptic drugs (antipsychotics)
Class Summary
The neuroleptic drugs are the most frequently prescribed agents for targeting behaviors such as aggression, self-injury, and hyperactivity in people with MR/ID. These indications are generally off-label for MR/ID and caution is advised. Increasingly, they are more likely to be reserved for the older child or adult in whom intensive behavioral intervention has failed. Likewise, the prevalence of comorbid psychiatric disorders in MR/ID increases with age. Neuroleptics interact with receptors for a variety of brain neurotransmitters, including dopamine, serotonin, acetylcholine, histamine, and norepinephrine. Their ability to antagonize dopamine receptors appears to correlate with the efficacy of these drugs and imparts their antipsychotic properties. Likewise, antidopaminergic activity evokes extrapyramidal symptoms. Rarely, neuroleptic malignant syndrome may occur.
Risperidone (Risperdal)
Atypical antipsychotic with fewer adverse neurologic effects and less propensity for extrapyramidal movements (eg, pseudoparkinsonism, akathisia, acute dystonias, tardive dyskinesia).
Aripiprazole (Abilify)
A newer atypical antipsychotic, aripiprazole is indicated in acute bipolar mania and schizophrenia.
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| Category | IQ score* (SD below mean) | Proportion of MR/ID | Educational level/adaptive skills | Intensity of supports required | Prevalence in total population |
| Mild | 50-55 to 70 (2-3) | 85% | Up to about 6th grade; vocational | Intermittent, especially under stress | 0.9-2.7% |
| Moderate | 35-40 to 50-55 (3-4) | 10% | up to about 2nd grade; unskilled or semi-skilled, supervised | Limited; usually supervised | 0.3-0.4% |
| Severe | 20-25 to 35-40 (4-5) | 4% | May learn words; elementary self-care skills | Extensive; closely supervised group or family home | |
| Profound | < 20-25 (>5) | 1% | Little to no self-care skills | Constant aid and supervision | |
| *IQ scores are considered +/-5 points due to measurement error. | |||||
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