7.1 Autism

This disorder is one among the Autistic spectrum disorders (ASDs), the latter further comprises of atypical autism and few allied complications in addition to Asperger’s disorder (Cass et al. 2008). Autism is regarded as an intricate neurodevelopmental condition in which patients demonstrate reduced give-and-take communicational behaviours in addition to limited, monotonous or stereotyped performances (Barbaresi et al. 2006). A heterogeneous population of youngsters suffering from autism is usually observed. The issue of the neurological condition autism and allied complications stands potentially important and intriguing due to enthused community apprehensions regarding the actual enhancement in the autistic cases and associated disorders. The mechanism of the induction of ASDs is quite indistinguishable; moreover, the psychological or therapeutic practices yield unsatisfactory consequences. This is due to this probable reason also that much consideration is given to dietary factors, additional environmental agents and complementary treatments (Barbaresi et al. 2006). In this perspective, one of the concepts known as “leaky gut” conception has gained enough consideration. This perception has further been extended to another proposed reason that is the performance of vaccination. For instance, there has been enough debate going on the potential role of measles-mumps-rubella (MMR) vaccine and induction of autism. According to this hypothesis, the latter vaccination enhances the permeability of gut causing “leaky gut”. However, there isn’t enough epidemiological or ecological data to build a correlation between induction of autism and MMR vaccination. The concept of “leaky gut” is further strengthened by the studies of Cade and coworkers who observed peaks in the urine samples with increased number of peptides in such neurological patients including schizophrenia and autism (Cade et al. 2000). Nevertheless, the fractions that contain these peaks haven’t been characterized comprehensively. Consequently, the nutritional interference that seemingly led to ameliorations was free from dairy and wheat linked casein and gluten respectively. Moreover, this concept is still dominating and has been the main foundation of the diet formulation for ASD subjects. This concept is further supported by the studies of Reichelt and Knivsberg who proposed a model known as “autism model” that proposes that food derived peptides (exorphins) and serotonin uptake modulators are the key players in the establishment of autism (Reichelt and Knivsberg 2003). They further added that there is some genetic base to strengthen the model in terms of the gene deficiencies that expresses at least two or more enzymes (peptidases) and/or some other proteins that regulate these enzymes. On the other hand this proposed model has been a subject of controversy by many other investigators. The subsequent reports with application of more sophisticated bioanalytical techniques including LC/MS couldn’t detect these peptides. The other investigators also couldn’t confirm the presence of these opioid peptides in the urine of autistic patients. They also couldn’t develop a correlation between development of autism and deficiency of the brush border enzymes like dipeptidyl peptidase IV (Hunter et al. 2003). The other research group exploited mass spectroscopy (MALDI-TOF/MS) for analysis of such peptides (opioid). However, the investigators couldn’t find any evidence of such peptides in the urine of autistic patients. They finally concluded that these opioid peptides can’t be regarded as marker (biomedical) for such diseases. These peptides may not be engaged to analyse the response to diets containing casein or gluten (Cass et al. 2008). The other researchers in 2006 thoroughly studied the diet formulations (gluten and casein-free) and concluded that there aren’t enough evidences to formulate recommendations about these diet elements. Moreover, they stated that the casein and gluten-free diets should be analyzed first and the consequential parameters must comprise of evaluation of non-verbal cognizance (Christison and Ivany 2006). In 2007, Dettmer and coworkers while working on food derived opioid peptides like BCMs, gliadinomorphin, deltorphin-1 and deltorphin-2 couldn’t find these peptides in the urine of autistic children (Dettmer et al. 2007). Subsequently, Millward and coworkers published a review in this research area. They concluded that the application of complementary and alternative therapies (CAM) for autistic patients with casein and gluten-free diet formulations couldn’t provide enough encouraging results (Millward et al. 2008). This scientific literature in this research area isn’t in a position to formulate recommendations regarding establishment of autism and intake of gluten and/or casein-free diets.

7.2 Exorphins and the Central Nervous System (CNS)

7.2.1 Distribution of Receptors for Opioids in the CNS

Receptors for endorphins or exorphins are extensively located in the brain, spinal cord, autonomous nerves and peripheral sensory nerves (Wittert et al. 1996; IUPHAR 2008; Peckys and Landwehrmeyer 1999). These receptors through their corresponding ligands (endorphins and exorphins) have numerous and rather varied actions and manifestations. These effects include sedative actions, analgesic actions, euphoria, eating and appetite behaviours, dysphoria, depression in respiration, cough reflexes, vomiting, nausea and pupillary constriction. The mu-receptors (related to morphine agonists) are reported to interact with the milk derived exorphins like BCMs (Brantl et al. 1981, 1982; Koch et al. 1985). These μ-receptors for BCMs are distributed in the caudate putamen, thalamus, nucleus accumbens neocortex, interpeduncular complex, amygdala, and inferior and superior colliculi (IUPHAR 2008). The receptors (μ) are also expressed in the dorsal horn (the superficial layers) of the spinal cord. Moreover, a medium density of these receptors is also expressed in raphe nuclei and periaqueductal gray. These areas in the brain have well-developed role in the induction of pain and analgesic effects. Morphine and other opioid compounds including fentanyl are classified in the ligands that bind μ-receptors. Besides these effects, these demonstrate role in other processes including respiration, cardiovascular functions, transit of intestine, behaviours, mood changes, heat regulation, secretion of hormones and some immune effects.

7.2.2 Action of Exorphins on CNS

There are many animal reports that show the role of bovine milk derived BCMs in the CNS. The peptides were administered to these experimental animals parenterally, except for the animal report where the effect of soymorphins peptides was observed by Ohinata and coworkers (Ohinata et al. 2007). It was Brantl and coworkers for the first time in 1981 and parallely Grecksch and coworkers in the same year who reported the analgesic effect of BCMs when these peptides were injected into the intracerebro-ventricules. The work was more enthusiastic because of the reason that the study didn’t include single but four different BCMs ranging from four to eight amino acid residues marked as BCM-4, BCM-5, BCM-7 and BCM-8. The results were promising as the trials revealed analgesic effect of these peptides. Additionally the effect was entirely reversed by the μ-opioid receptor antagonist, naloxone. Moreover, the relative responses revealed that although BCM-7 demonstrated slowest commencement of action, but the same response occurred for longer time duration of 90 min. The investigators highlighted based on the long time duration that lasted even more than endorphins they have assessed. Paroli in 1988 observed sedative and analgesic effects of these peptides on CNS when administered directly in blood (Paroli 1988). Moreover, initial neonatal interaction of experimental animals (rats) to the opioid peptide (morphiceptin) induced hyper analgesic condition in later life (4.5 months) (Zadina et al. 1997). These observations therefore infer that the correlating this animal data to humans need more well-designed studies, because of the wide variations in developmental stages of neonates (humans). Based on these preliminary animal experiments, many researchers validated the role of these bovine milk derived BCMs in the central nervous system of experimental animals when administered parenterally. The full details are shown in Table 7.1.

Table 7.1 Effect of bovine milk derived BCMs on central nervous system in different animals when administrated through different routes
Full size table

7.3 A1 Cow Milk Consumption and Neurological Disorders

Many correlations that have associated consumption of cow milk β-casein with neurological diseases including autism, schizophrenia, SIDS and post-partum depression (Sun et al. 1999, 2003; Sun and Cade 2003). These complications are very significant for considerations as only little treatment choices are available and remarkably very annoying for the family members. There are some studies available that have tried hard to demonstrate the relation, but this maiden data is challenging. The researchers at the Florida University postulated that the BCM-7 crosses the blood-brain barrier and acts on the brain cells and hence induces the symptoms linked with autism, schizophrenia and SIDS (Sun et al. 1999, 2003; Sun and Cade 2003). Studies have established that the antibody titers (IgG) against BCM-7 are present in major of the patients (90%) and 86% suffering from schizophrenia and autism respectively. Additional reports have demonstrated remarkably increased levels of this peptide (BCM-7) in blood and cerebral spinal fluid in these patients compared to normal subjects. The increase in the levels of BCM-7 and in turn enhanced antibody titers may be due to the deficiency or lacks of enzymes that have specificity for these proline rich peptides like dipeptidyl peptidase-4. Alternatively, there may be increased immature gut or increased gut permeability to allow these peptides to cross the gut barrier and reach the circulation. It is also possible that cumulative action of the two mechanisms may work together to correlate BCM-7 with neurological conditions. In order to fully rely on the hypothesis that regards this opioid peptide is associated with the neurological symptoms. It is significant to characterize, confirm and validate the findings that this peptide crosses the blood brain barrier. To validate the findings that this opioid peptide really crosses the barrier between blood and brain in a carrier-dependent manner (Banks and Kastin 1987; Pasi et al. 1993). The other possibility is that it is not essential for the whole opioid peptide to cross this barrier to create these complications, instead only a subgroup of the opioid peptide is essential to cross.

7.3.1 Animal Studies

The animal trials were carried out in rats and administered with different doses of BCM-7 opioid peptide. The presence of this peptide in different regions of the brain was assessed in terms of immuno-reactivity (FOS like) (Sun et al. 1999). The effect was expressed as the regions affected when there was an increase in the number of stained cells compared to the regions of brain taken from rats infused with normal saline. The results indicated increase in the regions of brain affected by BCM-7. The temporal and occipital cortex (speech center) was observed to be strongly affected. Moreover, it is quite evident that the patients with autism and schizophrenia have abnormal patterns of speech. Additionally, there is a disruption in the levels of dopamine, serotonin and γ-aminobutyric acid (GABA), the disturbance in the latter leads to diminished or lack of social interactions that are representative of the neurological conditions. This is quite clear that this peptide is released in gastrointestinal tract from A1 β-casein. However, other peptides resembling this peptide are released from wheat gluten and named as gliadinomorphins. The investigators postulated that a remedy can be acquired from these neurological conditions while taking a diet free from gluten and casein (Sun et al. 1999, 2003; Sun and Cade 2003). The same research group in 1999 administered intraperitoneally BCM-7 to rats to check the changes in behaviour or demonstrate analgesic effect (Sun and Cade 2003). The results indicated significant changes after time intervals (2 h). With first minute, the animals showed restlessness and enhanced respiratory. The animals were observed to be lethargic and demonstrated decreased social interaction after 7 min. There were non-significant changes observed in rats infused with normal saline. Moreover, the rats co-administered with BCM-7 and naloxone (BCM-7 antagonist) also exhibited non-significant changes. This is due to the fact that naloxone blocks the μ-opioid receptor pathway exploited otherwise by opioid peptide BCM-7. These observations therefore support the role of this opioid peptide BCM-7 in the pathogenesis of neurological complications like autism and schizophrenia. The same investigators in an attempt tried to explain the associationship between BCM-7 and SIDS (Sun et al. 2003). BCMs in general and BCM-5 and BCM-7 in particular have been found to be strong opioid agonists. More importantly, BCM-5 is found to be around ten times more potent compared to morphine and the other peptide (BCM-7) almost equally potent. However, there is insufficient data that clearly regards BCM-7 as a hypothetical risk factor for SIDS. The discussion on whether A1 β-casein from bovine milk releases BCM-7 during gastrointestinal digestion and then the latter correlates with SIDS is both potentially important and intriguing. Some animal trials have depicted a depression in respiration resembling that of SIDS when BCMs are directly administered in intra-cerebroventricular cavity. On the other hand, there are other reports that have correlated consumption of BCMs and SIDS positively. Studies have also shown high levels of BCMs in the cerebrospinal fluid of respiratory distress infants compared to normal ones. On one hand insufficient findings can’t conclude a strong correlation between BCM consumption and SIDS. But on the other hand the data depicting intake of bovine milk, respiratory distress and changes in behaviour can’t be overlooked. Therefore, to establish a strong correlation between the BCM intake and SIDS, the presence of these peptides in the cerebrospinal fluid, plasma or serum should be estimated with advanced techniques like mass spectroscopy, ELISA and analytical HPLC methods. Moreover, well-designed human trials should be performed involving neonates with disturbances in respiration and healthy neonates for perfect assessment. There are also few ecological studies that link A1 bovine milk consumption and neurological manifestation like schizophrenia and autism. Reports have also estimated higher levels of this peptide (BCM-7) in the blood (Lindstrome et al. 1984; Reichelt et al. 1990) and urine (Cade et al. 2000; Reichelt et al. 1991) of subjects suffering from neurological complications including autism, schizophrenia and postpartum psychosis. To date the possible mechanism formulated claims the release of BCM-7 during gastrointestinal digestion from A1 bovine β-casein, transport of this peptide through gut, entry into the circulation, crossing the BBB and finally expressions of neurological disorders (Sun et al. 2003). The hypothetical link between A1 milk consumption and schizophrenia and ASD doesn’t tell about cause of the neurological conditions but to the exacerbation of signs linked with these neurological complications. More specifically, it may be concluded that this peptide may exaggerate indications connected with these complications. There are also a number of laboratories located in USA and Europe that assess BCM-7 levels in urine with a purpose of nutritional intermediation for the management of ASD patients. In this perspective, Cade and coworkers in 2000 revealed that a diet free from gluten and casein was complemented by amelioration in 81% of autistic patients within 3 months (Cade et al. 2000).

7.3.2 BCMs and Sudden Infant Death

The depression in respiration with opioids is a well-established fact. In medical terms it may be put forward that depression in respiration decreases the usage of analgesia (opioid). The principle effort for respiration is produced in the brain stem. This is controlled by elements which comprises of conscious feedbacks from the central (brainstem), cortex, and peripheral receptors (chemo) which sense alterations in the biochemical elements of the blood (Pattinson 2008). There are number of ways through which opioid weaken the respiration and includes various sites (neuronal) on which they may show mechanism of action. Also some differences are manifested due to the diversity in the opioids and that may exist in a specific group also (e.g. μ-receptor binding molecules). More generally there are some correlations between sleep disturbances and apnea and use of opioids (Wang and Teichtahl 2007). The receptors for opioids and sleep regulation are positioned in the same regions of the brain (nuclei) and these peptides (opioid) are proposed to have a role in the stimulation and maintenance of the sleep state. Whenever there is a change in stimulation, maintenance and removal of opioids, irregular sleep patterns have been stated. The reduction in REM (rapid eye movement) sleep has been observed during opioid induction and maintenance. In addition to this central sleep apnea (CSA) has been documented with use (chronic) of opioids.

The mechanism of SIDS induction is complicated and multifactorial. It is the source of mortality of newborns from first month to first year of their age (Brooks 1982). Sun and coworkers in 2003 stated that the common factor for all the children that suffer with SIDS is the consumption of milk. The latter is the complete diet of the infants, when digested in their gastrointestinal tract and release BCMs. Since the gut of the infants is immature therefore possess leaky gut that provides enough chances for these peptides to cross the gut reach blood and finally cross BBB. In the brain of those infants that have irregular respiratory regulation and development of vagal nerve, BCMs release from milk may prompt depression of the brain-stem respiratory centers that ultimately leads to death (Sun et al. 2003). The other investigators have claimed that the opioid peptide (BCM-7) that is rich is proline is resistant to digestion and more immature gut of infants provides enough possibilities for this peptide to be absorbed and affect various receptors in the endocrine, nervous and immune systems (Bell et al. 2006). On the other hand, the transports of these peptides out of the CNS have also been established in few animal models. Although the above studies provide various proofs in favour of the hypothesis, however more research is needed in this field. These pieces of evidence are strong but not strong enough to make final nutritional recommendations to the public in general and autism and schizophrenia patients in particular. There is an enhanced comprehension of how this opioid peptide (BCM-7) may lead not only to symptoms of autism but also to fundamental abnormal neurological development linked to the serotoninergic system (Kost et al. 2009). There are also reports available that demonstrate that children suffering from autism show digestive problems and help BCM-7 to absorb and reach circulation (Cade et al. 2000). Nevertheless, the issue is still controversial. The preliminary reports performed in animals show that BCM-7 is absorbed and crosses blood-brain barrier and causes autistic manifestation (Sun and Cade 2003). Surprisingly, the human trials involving milk elimination have showed positive inferences (Knivsberg et al. 2002), however, the same is criticized because of lack of double blind protocols.