Galileo and DSM.

Salvioti’s insight—that the earth is not the center of the universe—which clashed with 2000 years of Ptolemaic assumptions, is a useful metaphor as we ponder the predominant influence of the Diagnostic and Statistical Manual of Mental Disorders (DSM) on neuroscience. Since the birth of DSM half a century ago— a significant step forward in legitimizing psychiatry— new insights in the genesis of human behavior (region-specific brain function, neurotransmitters, and thermodynamic laws) have emerged. Today, for instance, there is recognition that the amygdala plays a key role in our fear responses, the prefrontal cortex mediates mood and executive function, and the thalamus is a crucial filter for sensory input. Molecular advances have also provided a framework of knowledge about key neurotransmitters and neuromodulators, such as brain-derived neurotropic factor, G protein, CAMP, and others. In contrast, concepts regarding complexity, butterfly effect, and eigenvalues, by and large, have received sparse attention in the neurosciences. Richard D. Feynman’s observation, ‘‘Nature is absurd from the point of view of common sense,’’ offers a glimpse into the mismatch between DSM and neuroscientific advances. Due to our sensory limitations, nature may seem absurd. There are many influences that are unobservable by our sensory system but that can be explained through eigenvalues such as gravity, sound waves, or vibration. The theories of Poincare and Lorentz propose that complex systems (e.g., brain function) are vulnerable to initial errors. This phenomenon, which is recognized as the butterfly effect, suggests that an early diagnostic error may lead to delayed and magnified adverse outcome. It is plausible that a major DSM flaw—to classify ‘‘disease,’’ ‘‘disease complication,’’ or ‘‘disease progression’’ as independent ‘‘comorbid disorders’’—has inhibited a pathophysiologically sound pursuit of accurate diagnosis. It is also plausible that various DSM disorders are artifacts or complications of not yet recognized brain dysfunctions. For instance, addictive disorders, depression, and schizophrenia may represent ‘‘disease complications.’’ Two independent observations seem to support the possibility that addictive disorders are complications of brain dysfunction: