What research is being done on autism?

The U.S. National Children's Study, neurotoxicology, study design. Environ Health Perspect 113:1437-1446 (2005). doi:10.1289/ehp.7672 available via http://dx.doi.org / [Online 24 June 2005 - copy paste 10.1289/ehp.7672 in the doi field] set out to investigate and attempt to quantify the effects of environmental exposures on child development.
The fundamental lesson learned from studies of the effects of environmental exposures to the foetus and child is that the developing brain is one of the organs in the human body most sensitive to damage. Functional manifestations ranging from frank mental retardation to milder learning disabilities are the most common class of birth defects (Lipkin 1991).

In what has become known amongst clinicians as 'classical autism', the child is born with a compromised immune system, a compromised gastro-intestinal tract and as a consequence of the above, compromised neurological function.
Regressive autism occurs when there has been 'normal' development of faculties to a point in time and then an acute loss of function occurs. Usually, this is a result of toxic insult to the immune, gastro-intestinal and consequently, the neurologic systems of the body.

Clinicians and researchers in the field of Autism Spectrum Disorders (ASD), ADHD and associated learning and behavioural disorders are now in the midst of a paradigm shift.
This shift involves discarding old beliefs and myths around ASD and acknowledging that these children are medically sick
Clusters of symptoms affecting this axis may include:­-
Central Nervous system (Neurologic) problems
Altered sensory sensitivity - Children with autistic disorder often present with hyper or hypo sensitivity to the senses of taste, smell, touch, pain, light, sound etc. That is, an abnormal processing of sensory input.
Altered anatomic and architectural differences in brain structure.
Neuronal development is a delicate and intricate process and may be interrupted in autistic individuals due to toxic insult at time critical stages of development.

The Blood Brain Barrier
One dogma that still persists is that the blood brain barrier protects the brain at all times and lets nothing through that may be detrimental.   
Whilst it does protect the brain to a certain extent from exogenous insult, we now know that the blood brain barrier is not as effective as we used to think.
The integrity of the blood brain barrier can be compromised (by whatever means in development and growth) and gaps may form between the cells allowing toxins to enter directly via the blood stream causing inflammation of neuronal tissue. If insult at critical stages of embryonic and early development occurs as illustrated in the Stages of Brain Development article, deficits in cognitive function will occur.
Recent neuroscience research in this area of early development of the foetus into detection of developmental delay and autism has found that three times the amount of placental trophoblast inclusions were found in the placental tissue of those children born with developmental problems than in controls. ( "Placental Trophoblast Inclusion in Autism". Anderson et al., Biological Psychiatry, epublished June 23, 2006. )

The brain is not a static entity.   It responds to drugs, to foods, to exercise, to hormones, to nutrients.  It is composed of innumerable cells which perform a wide variety of functions.  It reacts, it repairs, it is dynamic, it is living.
Some researchers have noted that the autistic brain has smaller memory (amygdala), emotion (hippocampus) and learning centres (cerebellum) than normal. The autistic brain does not seem to function at all like a normal brain. Neuroscientist, Eric Courchesne and colleagues have used deep brain scans to show that the fusiform gyrus (part of the brain involved in face recognition) isn't active in autistic children. Other studies report dysfunction in the parietal lobes and the corpus callosum. The anatomical and functional abnormalities strongly suggest dysfunctional genes and misguided development. So far, a gene called WNT2 and another called HOXA1 (both involved in early brain development) and a third gene that codes for serotonin are likely candidates. It is estimated that 10 or more genes may ultimately be implicated.

Structural imaging studies reveal:
 Cerebral atrophy7
 Ventricular Dilation1
Abnormal ventral temporal cortical activity during face discrimination among individuals with autism and Asperger's Syndrome9
Various abnormalities of cellular migration10
Anterior and medial temporal lobe abnormalities11
Decreased neuronal size and increased cell packing density has been observed in the hippocampus, entorhinal cortex and amygdala suggesting cells are fixed at an earlier stage of brain maturation.

Mirror Nuerons and Autism
Mirror neurons, discovered in the late 1990's, are a subset of neurons that are activated when an individual performs certain actions as well as when we observe another performing the same actions or movements. These neurons provide a direct internal experience and therefore understanding of another person's act, intention or emotion.
They appear to underlie the ability to imitate another's action, and thereby learn. The 'mirror mechanism' is a bridge for communication and connection on several levels.

A complementary hypothesis to the mirror neuron system - the salience landscape theory - could account for some secondary symptoms of autism such as hypersensitivity.
One group of researchers decided to explore the possibility that children with autism have a distorted salience landscape, perhaps because of altered connections between the cortical areas that process sensory input and the amygdala or between the limbic structures and the frontal lobes that regulate the resulting behaviour. As a result of these abnormal connections, any trivial event or object could set off an extreme emotional response-an autonomic storm-in the child's mind.
This hypothesis would explain why children with autism tend to avoid eye contact and any other novel sensation that might trigger an upheaval. These distorted perceptions of emotional significance might also explain why many children with autism become intensely preoccupied with trifles such as train schedules while expressing no interest at all in things that most children find fascinating.
Their findings, observing galvanic skin response or skin conductance, indicated that children with autism tend to have a much higher level of autonomic arousal than normal children.
Therefore any approach which aims at balancing autonomic function such as gentle bodywork therapies such as the Bowen Technique and CranioSacral Therapy, will be beneficial to autistic individuals.
Immune System Difficulties
Altered sensitivity to - toxins (pesticides. gas-off from building materials and furnishings ~ preservatives, food colourings, flavour enhancers, processed food additives), foods (gluten, casein, yeast, sugar, salicylates), heavy metals (mercury, cadmium, arsenic, lead, aluminum etc), infections (bacterial, viral, yeast), vaccinations
Abnormal processing - autoimmune dysfunction, fungal, bacterial and viral infections
Autistic individuals appear to be particularly susceptible to candidiasis - candida albicans - a yeast overgrowth with the potential to breach the bowel and cause intestinal permeability. Candida has the potential to turn from yeast to a fungal infection and the rootlets grow into the intestinal barrier and attach themselves to nervous tissue20.. - See Intestinal Permeability later in this article.
Digestive Abnormalities
Altered enzyme function
Changes in bowel flora - increased harmful (toxic) bacteria
Increase in intestinal permeability to antigens, peptides and toxins
Biochemical Abnormalities
Defective detoxification leading to toxic overload is common in autism, therefore support of detoxification pathways - liver etc. is desirable.

Intestinal Permeability
Intestinal Permeability is an ailment of the digestive system characterised by the inability of the intestines to prevent the "leakage" of large particles (Antigens) through the intestinal wall into general blood circulation. It is universally found in autistic individuals.
Intestinal permeability is a poorly recognised but extremely common problem. It is rarely tested for. Essentially, it represents a hyperpermeable intestinal lining whereby large spaces develop between the cells of the gut wall, and bacteria, toxins and food leak in to where they shouldn't.
If the gut is not healthy, neither is the rest of the body. It is the point of fuel and nutrient entry.
In some cases of intestinal permeability whole bacteria, the toxins produced by bacteria (endotoxins or Lipopolysaccharides) and other antigens are able to permeate the intestinal wall or gastric mucosa and enter the lymph glands, lungs, liver and other organs where they produce various diverse ailments. When the antigen is a microorganism, this phenomenon is known as microbial translocation (when the microorganism is bacteria, the phenomenon is known as bacterial translocation).
During intestinal permeability, the epithelium of the villi of the small intestine becomes inflamed and dysfunctional impeding absorption of essential nutrients.
The Following Substances may Cause intestinal Permeability
Carbohydrates
Excessive consumption of simple sugars may cause intestinal permeability.8
Microorganisms
Candida albicans overgrowth (Candidiasis) may cause intestinal permeability (this occurs via the Acetaldehyde produced by candida albicans damaging the epithelial cells of the small intestine).'9
Some types of detrimental protozoa may cause intestinal permeability:
-  Blastocystis hominis may cause intestinal permeability.2
-  Yersinia enterocolitica may cause intestinal permeability.12
Pharmaceutical Drugs
Methotrexate may cause intestinal permeability.23
Non-Steroidal Anti-Inflammatory Drugs (NSAIDS) such as Ibuprofen may cause intestinal permeability (by inhibiting certain Prostaglandins that normally protect the intestinal wall).24 Pharmaceutical Antibiotics may cause Intestinal Permeability (by killing the layer of Beneficial Bacteria that reside in the Mucous Layer of the Intestinal Wall).
Courtesy of Learning Discoveries Psychological Services (Rosemary Boon)