Pharmacological Approach

Developmental intellectual disability is a daunting societal problem and affects 2–3% of the population in the industrialized world. Disorders involving intellectual disability although narrowly defined by an IQ <70 and by deficits in academic, adaptive and interpersonal skills, are widely diverse in their causes from genetic disorders such as Down syndrome to neurodegenerative conditions such as Alzheimer's disease. Unraveling the molecular basis for cognitive impairment for these conditions has been a very challenging scientific endeavor. However, recent advances have suggested that there may be a common mechanism that underlies the manifestations of learning and memory deficits in intellectually disabled children and adults.

Neurons in the brain transmit and process information through electrical and chemical signaling. The transmission of signals occurs at functional connections between neurons known as synapses. The main effectors of chemical signaling at the synapses are neurotransmitters which bind specific receptors on target neurons. These interactions between specific classes of neurotransmitters and receptors result in either excitatory effects which increase signaling or inhibitory effects which decrease signaling.

Synaptic plasticity is the ability of synapse to change efficacy based on previous activity and is considered the cellular basis for information processing and memory formation, consolidation, retrieval and extinction. A proper balance of inhibitory and excitatory signaling at the synapse permits this process to occur.

Recent research at Stanford University and elsewhere has shown that over-inhibition, excess inhibitory signaling at synapses, may be the molecular basis for cognitive impairment in Down syndrome and potentially other intellectual disabilities. Restoring the proper balance between inhibition and excitation at the neuronal synapse by antagonizing excessive inhibitory circuits is a pharmacological approach that could result in the appropriate plasticity for memory and learning to occur in many conditions of intellectual disability.