Bruce Miller and his coworkers (Miller et al., 1998; Miller, Boone, Cummings, Read, & Mishkin, 2000) wrote a series of papers on the emergence of artistic talents in a form of degenerative dementia called frontotemporal dementia, or frontal temporal lobar atrophy. The two most common forms of degenerative dementia that are seen in the clinic are Alzheimer's disease and frontotemporal dementia. Most patients with Alzheimer's disease start off with a memory loss and then develop other cognitive deficits, such as problems with naming, route finding, drawing, copying, and even performing learned skilled movements (ideomotor apraxia). The signs and symptoms associated with frontotemporal dementia are often different from those seen with Alzheimer's disease. In one form, patients lose their social skills and perform antisocial acts. Some patients may also become abulic and sit around all day doing nothing useful. Other patients with frontotempo-ral dementia might have a language deficit that causes their speech to become progressively less fluent or they might have trouble with naming and comprehension; unlike patients with Alzheimer's disease, their visual-spatial memory might remain intact. When we obtain brain images (MRI) from patients with Alzheimer's disease, we often see atrophy in the medial temporal lobes and in the parietal lobes, but patients with frontotemporal dementia may have atrophy of the frontal lobes or anterior temporal lobes or both. In addition, frontotemporal dementia might be asymmetric and primarily involve only one side of the brain. Unlike patients with Alzheimer's disease who on microscopic examination of the brain have deposits of amyloid (plaques) and tangled fibrils in their neurons (neurofibrillary tangles), patients with frontotemporal dementia have a variety of different microscopic changes, including intraneuronal inclusions called Pick bodies (after the neurologist who first described this syndrome), ballooned neurons that stain poorly, or even no specific pathological markers.

It is often difficult to know, in retrospect, when a dementing disease has started. Several of the artists described by Miller and his cowork-ers (1998 and 2000), however, appeared to have started drawing or painting prior to the time they had the symptoms and signs of a fron-totemporal dementia or at the time their dementia was just beginning. What was remarkable about these patients is that in spite of their dementia they continued to paint and some even improved their artistic skills. As I described earlier, the left hemisphere primarily mediates verbal activities and the right hemisphere appears to be more important for the type of spatial skills important in painting. Miller and his coworkers noted that most of these artistic people had degeneration that was limited to the left temporal lobe, sparing the frontal and parietal lobes, and that their creative skills were nonverbal. According to Sergent (1993), composers such as Ravel, who had a focal degeneration of his left hemisphere, could continue to be productive, but from Miller et al.'s reports we cannot learn if these people's talents existed before the onset of the dementia. Miller et al.'s reports do seem to indicate, however, that some patients increased their artistic skills during the time they had their dementing illness.

The reason stroke and degenerative diseases of the left hemisphere might enhance artistic skills is not entirely known. Patients with right-hemisphere injuries often demonstrate a syndrome called unilateral spatial neglect (Heilman, Watson, Valenstein, 2003). When these participants are presented with a long horizontal line and asked to mark the middle or bisect the line, they displace their bisection mark to the right of actual midline. To explain this deficit, Kinsbourne (1970) suggested that normally, to move one's eyes or direct one's attention to either the right or the left side of space in response to a lateral stimulus, the hemisphere opposite the stimulus would have to become activated and this activated hemisphere would also have to inhibit the opposite hemisphere. If the opposite hemisphere was not inhibited and both hemispheres were activated, the person or animal would not be able to move his or her eyes and attention to one side of space. Furthermore, when events such as stroke injure the right hemisphere, this damaged hemisphere is unable to inhibit the uninjured hemisphere, whereas the uninjured hemisphere continues to inhibit the damaged hemisphere. This activation imbalance between the two hemispheres induces an attentional-spatial bias such that the patient's attention is biased toward the right, and this rightward attentional bias leads patients to misplace their bisection mark to the right of actual midline. To help explain why brain injury can induce the emergence of a new or improved skill, Kapur (1996) suggested an explanation similar to that used by Kinsbourne to explain neglect. Kapur used the term "paradoxical functional facilitation" for the facilitation of a function induced by a lesion that destroys an inhibitory circuit. Miller and his coworkers (1998 and 2000) suggested that perhaps a similar phenomenon was occurring in their patients and that left anterior temporal lobe degeneration "contributed to the unexpected emergence of talent in our patients."

If a person has a focal injury to the brain, it does not preclude the possibility that other uninjured portions of the brain can develop new skills and enhance already acquired skills. We even demonstrated that, with practice, patients with dementia can reconstitute a skill that was previously impaired. For example, we demonstrated that three patients with probable dementia of the Alzheimer's type who were suffering with a name-finding disability were able to regain the ability to use words that they had lost (Leon et al., 2003). Thus, the finding that patients with focal left-hemisphere degeneration are able to acquire visual-spatial or musical skills does not mean that this degenerative process lead to the development of creativity. Unfortunately, there is no means by which Miller and his coworkers (1998 and 2000) could test this disinhibition postulate in their participants. There is, however, another model of brain injury that could be used to test this postulate. In patients with uncontrollable epilepsy, often the seizure focus is in either the left or the right temporal lobe. Although antiepileptic medications are used to control these patients' seizures, some patients cannot be controlled by medications and must have the epileptic focus removed. Surgeons do this by removing the anterior temporal lobe. These operations are performed often in medical centers around the country. Whereas some investigators have reported a decline of musical abilities with right temporal lobectomy and trouble with word finding following left temporal lobectomy, to our knowledge no one has reported an increase in verbal creativity with right temporal lobec-tomy or an increase of musical or artistic creativity with removal of the left temporal lobe. Before we can reject this "release" hypothesis, however, it needs to be experimentally tested, and this has not been done.

Finally, Miller and his coauthors (1998) used the term talent, and talent might refer to skill rather than creativity. Hence, it is not clear that these demented patients are truly creative as defined in this book. An increase of skills is not the same as an increase of creativity, and although Miller et al. provided evidence for the development of artistic skills, they did not provide evidence that with frontotemporal dementia there is an increase in creativity.

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