Getting to Know Savant Syndrome: Part VI

Darold Treffert MD
autism

What causes savant syndrome?

While a number of theories have been put forth to date, no single theory can explain all savants. Some of those theories have included eidetic imagery or the related but separate phenomenon generally called photographic memory; inherited skills; sensory deprivation and sensory isolation with overcompensation in isolated skills, compensation, ritualistic practice and reinforcement of very narrow skills to offset and compensate for lack of more general capacity or intelligence; and phenomenal memorizing ability. There are concerns with each of those theories. For example, formal testing shows the presence of eidetic imagery in some, but not all, savants. Two studies, one of 25 savants and another of 51 savants showed relatives with special skills or abilities in some, but not all cases; another study of 23 savants found only one family member with special skills. A number of studies, especially those looking at calendar calculating and prodigious musical ability, have demonstrated that savant abilities extend well beyond memorization alone as accounting for the special abilities, and have documented that literal, rote memory alone cannot provide a basis for the presence of extensive savant skills.

One theory, which quite consistently provides an increasingly plausible explanation for savant abilities in many cases, is left brain injury with right brain compensation. While left hemisphere/right hemisphere separation in the brain is an over-simplification, the fact is that the two brain hemispheres do tend to have specialized functions. The skills most often seen in savants are those associated with the right hemisphere, and those most lacking are those associated with the left hemisphere. A number of cases studied thus far do document left hemisphere damage on CT and MRI scans, and those imaging studies are also correlated with corresponding left-sided deficits on detailed neuropsychological testing. Further, recent PET scan studies, in previously normal, non-disabled older individuals where savant skills have emerged as a fronto-temporal dementia proceeds (see below), have shown defects in the left anterior temporal lobe. When those same PET scan studies were carried out on an 11-year-old autistic, artistic savant, the same left anterior temporal lobe dysfunction was present. PET studies have also shown particular defects in left hemisphere function in autistic people, with confirming left-sided findings on neuropsychological tests. Even before CT and PET imaging were available, pneumoencephalograms demonstrated left hemisphere abnormalities, particular in the left temporal lobe areas, in 15 of 17 autistic patients, four of whom had savant skills in music or mechanical interest areas.

In addition to left brain injury and right brain compensation, in the savant, it is postulated that there is corresponding damage to the higher level cognitive or semantic memory circuitry, with enhanced compensatory function in the lower level, more primitive, habit or procedural memory circuitry. This results in reliance on the characteristic automatic memory - exceedingly deep but very, very narrow - habit memory seen in all savants. Such left brain damage/right brain compensation, coupled with semantic memory damage and procedural memory compensation, produces, then, the emergence of right brain skills coupled with automatic memory typically and characteristically seen in savant syndrome.

What is the ‘treatment’ for savant syndrome?

Savant syndrome is not a disorder or disease by itself. It is, instead, a condition in which extraordinary skills and prodigious memory are grafted onto, or superimposed upon, a more basic brain dysfunction that rises from a developmental disability, or some other form of central nervous system disease or disorder. Therefore the “treatment” for savant syndrome is the same treatment as that directed toward the more basic central nervous system disorder, such as Autism or Asperger’s disorder, for example. Or in the case of individuals with some other form of CNS injury, for example, it would be those treatment and rehabilitation efforts as directed toward overcoming the residual symptoms from such injury.

The special skills and abilities the savant demonstrates, however, can be used as a useful tool in the overall treatment and rehabilitation efforts directed toward overcoming or lessening the handicaps from the more basic developmental disorder, injury or disease. In many cases those extraordinary abilities can be used as a way of engaging the handicapped person in improved communication capacity, improved social interaction, and improved mastery of even daily living skills with movement, than, toward greater independence overall. In that manner the savant skills can serve as a ‘conduit toward normalization’ for the savant and there are many individual examples of that posted on this web site and recorded in numerous other case reports and individual stories.

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