Recently, I heard the latter portions of the radio version of a play, “Lucy” by Damien Atkins, relating to autism and produced by L.A. Theatre Works. “Lucy” was originally performed and reviewed as long ago as November of 2007, but I was not aware of it until I encountered the production for radio about one week ago. The plot revolves around a couple (Vivian and Gavin) with a daughter (Lucy) who is 13 years old and has a severe form of autism. Of particular interest for the EMR readership is how Lucy’s mother, Vivian, views the relationship between the direction of human evolution and the prevalence of autism and the need for individuals with autism to receive therapy. (more…)
A minimal requirement for evolution via natural selection is heritable phenotypic variation that affects reproductive success, or more generally, genetic success. The concept of heritability is often used somewhat loosely in casual non-technical conversation, but there is also a precise technical definition – actually there are two widely-employed technical definitions, each of which is characterized below.
Consideration of the meaning and usefulness of heritability is prompted by the publication of a new study (Hallmayer et al., 2011) addressing the relative contributions of genetic and environmental variation in the origins of autism. (more…)
Mouse ‘models’ for psychiatric disorders, strains of mice genetically engineered by ‘knocking out’ a specific gene that mediates expression of the disorder, provide invaluable information regarding the genetic, developmental, physiological, and neurological causes of mental diseases in humans. One of the first mouse models relevant to autism was generated via knockout of a gene called FMR1, whose loss of function in humans causes an autistic spectrum condition called Fragile X syndrome (Kooy et al. 1996; Hagerman et al. 2009).
Amazingly, such mice can now be ‘rescued’ – that is – restored to essentially normal function for cognitive tasks that were formerly much impaired, via treatment with drugs that down-regulate one of their brain receptors for glutamate, called mGLUR5 (Dölen et al. 2007; Hagerman et al. 2009). Fragile X mice can also be rescued by knocking out one copy of the actual gene that codes for mGLUR5, which reduces the brain’s production of this receptor and thus mimics the impact of pharmaceutical treatment (Dölen et al. 2007). (more…)
We usually consider medicine as a predictive scientific endeavor, as methodical in application as noble in purpose. But for some diseases, such as schizophrenia, the first treatments showing any effectiveness, including lithium, chlorpromazine, and even electroconvulsive therapy, were discovered entirely by accident. After the discovery of the first antipsychotic treatments, a period of allegedly rational schizophrenia drug development ensued, focusing on drugs that block the brain dopamine receptor DRD2 that was considered, based on very limited evidence, as the critical lock for chemical antipsychotic keys. Some of the drugs worked – more or less, with serious side effects. Truly rational drug development, however, required understanding of the causal basis of disease, which for brain diseases like schizophrenia requires, to a considerable extent, understanding the dark inner workings of the brain itself.
But the causal basis of one relatively-simple brain disease, Fragile X syndrome, has, in the past few months, been deciphered – a true milestone in the touted medical march from brain to computer, lab bench to bedside. Afflicting about 1 in 3000 children, Fragile X is the most-common known cause of both intellectual disability and autism. A series of studies, led by researchers including Gul Dölen and Mark Bear at MIT (Dölen and Bear 2008) and Randi Hagerman at UC Davis (Hagerman et al. 2009), has identified the core neuronal defect caused by mutation of the fragile X gene, and shown they can fix it – literally cure it (Figure 1) – in mice. The fix involves (more…)