Developmental disabilities may result from complex interaction of genetic, toxicological or pharmacological (chemical), and social factors. Among these various causes, pharmacological exposure to drugs deserves special scrutiny, because they are readily preventable. This research demonstrates the consequences of anticonvulsant therapy that may contribute to transient cognitive disabilities (impairments of attention, memory, learning and/or social behavior).
Previous studies have found that anticonvulsant drugs may themselves cause changes in mental functions. They may be often mixed with neurocognitive behavior, depending on the drug used. There may be also temporary cognitive deterioration. The researchers in a new study assert that clinical experience must be used to identify the subgroup of children who remain at risk for significant and clinically relevant cognitive and behavioral adverse effects of antiepileptic drugs. In testing the effects of drugs on the cognitive functions of the epileptic child, they relied on three established postulates:
1. Connections between neurons increase in efficacy, in proportion to the degree of correlation between pre- and post-synaptic activity.
2. Groups of neurons, which tend to fire together, form a cell-assembly whose activity can persist after the triggering event and serves to represent it; and
3. Thinking is the sequential activation of sets of cell-assemblies.
Consequently, learning can be defined as the process by which an organism benefits from experience, so that its future behavior differs from that of a comparable organism lacking this experience. With epileptic children, that experience may be the use of anticonvulsant drugs.
Accordingly, a research effort from Brazil has focused on problems in recall information, believing there are a subset of difficulties in learning and memory deficits, probably resulting from anticonvulsant therapy in infancy. The authors of the study, “Possible Interferences of Chronic Anticonvulsant Therapy on Memory Performance,” are Ingrid Dragan Taricano PhD and Rosemary D. Silva Amorim, from the Faculdade de Biomedicina, Universidade de Santo Amaro, São Paulo, Brazil. The researchers will present their findings in full during the American Physiological Society’s (APS) annual meeting, part of the "Experimental Biology 2002” conference. More than 12,000 attendees will attend the conference being held at the Ernest N. Morial Convention Center, New Orleans, LA from April 20-24, 2002.
Methodology
Four children, eight years old, were distributed in two groups, each consisting of one boy and one girl. Healthy children that were not using any form medication composed the first group. The second group was formed by two children currently using anticonvulsive drugs (Phenobarbital and Valproic Acid). Forty-eight blocks, with four different geometric figures: triangle, square, rectangle and circle, in three different colors (blue, red and yellow), two different sizes (big and large) and two different thickness (thin and thick) and a printed card were used in the experiment. Subjects were encouraged to observe the card containing eight images from different pieces, displayed in two parallel rows.
This process was repeated five times, with a 30 minutes interval between each session. During the interval, children were distracted with other activities. During the fifth session, children were told to withdrawn the pieces from the box and reproduce the card on the table, without seeing the card and also without instructions from the physcopedagogue (psychological teacher). Twenty-four hours after the last session, children were asked to recall the previous information, again without seeing the card and also without instructions.
Results
Valproic Acid and Phenobarbital are anticonvulsants used to control certain types of seizures in the treatment of epilepsy. Both may be used alone or with other seizure medicine. Like all such anti-epileptic medicines, they cause some degrees of sedation, so learning may be affected once that concentration is disturbed. In epileptic patients, cognitive functions can be affected by several factors individually or in combination. Alteration of cognition might reflect a chronic adverse effect, but the negative effects of these drugs are only one of several factors that may influence cognition.
In general, the cognitive effects of most antiepileptic drugs are modest and offset by their benefit in reducing seizures. Nonetheless, the cognitive effects may be clinically significant when treating specific patient populations, such as children and the elderly. This is evidenced by the research results from this small sample, which showed a deterioration in recall information from chronically treated children.
Conclusions
The findings suggest that proper cognitive development among epileptic adolescents demands a new cooperative effort between physicians who describe necessary antiepileptic drugs (and another) and educators, who observe that the consequence of chronically using these medicines may possibly decrease memory and/or learning dysfunctions. Such a partnership would combine experts with knowledge of probable collateral medicine side effects as these, and those responsible for stimulating cognitive processes. This would lead to a preventative effort to diminish cognitive impairment in a population group that suffers most from the effects of this disorder.
The American Physiological Society (APS) is one of the world’s most prestigious organizations for physiological scientists. These researchers specialize in understanding the processes and functions underlying human health and disease. Founded in 1887 the Bethesda, MD-based Society has more than 10,000 members and publishes 3,800 articles in its 14 peer-reviewed journals each year.
APS Newsroom: April 20-24, 2002
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