Multiple sclerosis: nature or nurture?

Interferon-β in the treatment of relapsing–remitting multiple sclerosis

The role of interferon-beta as a disease-modifying drug (DMD) for the treatment of relapsing-remitting multiple sclerosis (RRMS) is now well established, and its efficacy has been demonstrated unequivocally in large-scale clinical trials. However, current evidence suggests that in order to increase the benefit of therapy, use of an effective drug and dosing regimen should be commenced early in the course of the disease, a finding that places new emphasis on the need for early diagnosis. Indeed, it is now known that MS lesions often develop at a subclinical level and that axonal damage occurs even in the very early stages of the disease. Moreover, such damage may be irreversible, and there is strong evidence to suggest that efficacy lost as a consequence of delay in the onset of treatment or the use of a suboptimal drug regimen cannot be regained. At present, the choice of interferon-beta is complicated by the availability of 3 different products, each with a different dosing regimen. Although the optimal interferon-beta dosing regimen for RRMS has been the focus of much discussion, the issues of dose, and particularly dosing frequency, have not been satisfactorily addressed in clinical trials until recently. Over the last 2 years, however, 3 comparative studies of interferon-beta products have been conducted. The results obtained from these recent trials underline the importance of both dose and dosing frequency and indicate that for improved efficacy in RRMS, interferon-beta therapy should be administered frequently at the highest tolerable, and thus most effective, dose.

The varicella zoster virus: a pilot trial of a potential therapeutic agent in multiple sclerosis

There are a number of similarities in the geographic, latitudinal, and epidemiological features of multiple sclerosis (MS) and varicella (V). In the experimental model of MS, repeated high antigen doses (myelin basic protein) have deleted both the clinical and pathological manifestations of the disease. Therefore, it seemed appropriate to explore the effects of varicella zoster vaccine on patients with MS. Fifty patients with chronic progressive MS were vaccinated with attenuated varicella virus vaccine and followed for one year. Fourteen patients improved, four became worse, and twenty-nine were unchanged. All patients were seropositive for varicella before vaccination and all had a rise in varicella antibodies after the vaccinations. There were no major untoward results from the vaccine. Four patients developed mild chicken-pox after vaccination. This was a short-term pilot trial without control subjects. Thus, the apparently favourable clinical and magnetic imaging changes must be assessed with caution, as must the lack of adverse effects.

HLA and prognosis in multiple sclerosis

The patients of a multiple sclerosis (MS) incidence cohort with 25 years of longitudinal follow-up were typed for HLA-DR and DQ. This type of cohort provides reliable data for gene frequencies and prognostic studies. The influence of sampling bias, mainly due to mortality during the long follow-up, was accounted for. A positive association between MS and DR15,DQ6 was confirmed, but this haplotype did not influence prognosis. There was no difference in haplotype frequency between relapsing-remitting and primary chronic progressive MS. DR17,DQ2 was significantly over-represented in the quartile with the most malignant course. The haplotype DR1,DQ5, which was found rather less frequently in MS patients, also tended to be associated with a poorer prognosis.

Relationship of nocturnal melatonin levels to duration and course of multiple sclerosis

Multiple sclerosis (MS) is the most common of the demyelinating diseases of the CNS. The clinical course and prognosis of the disease are variable. Characteristically, the illness tends to progress in a series of relapses and remissions. Over the years there is a tendency for the patient to enter a phase of slow and steady deterioration of neurologic function. In about 10%-20% of patients, the course of the disease is not punctuated by a fluctuating course, but rather by an inexorable progression from the onset. The pineal gland has been implicated recently in the pathogenesis and clinical course of MS. Since MS is generally a chronic progressive disorder, we predicted an association between duration of illness and the activity of the pineal gland. To investigate this hypothesis further, we studied nocturnal plasma melatonin levels in relation to duration of illness in a cohort of 32 MS patients (4 men, 28 women; mean age: 41.1 years; SD = 11.1; mean duration of illness: 13.1 years; SD = 12.4) randomly selected from consecutive hospital admissions to a Neurology service for exacerbation of symptoms. For the purpose of comparison, we also studied in the sample serum prolactin levels. The cohort included 7 patients in whom the duration of illness since onset of first neurological symptoms was < or = 5 years (mean: 3.0 years +/- 1.1) and a cohort of 25 patients in whom the duration of illness was > 5 years (mean: 15.6 years +/- 12.7).(ABSTRACT TRUNCATED AT 250 WORDS)

Multiple sclerosis: relationship between seasonal variations of relapse and age of onset

The incidence of multiple sclerosis (MS) is age-dependent being rare prior to age 10, unusual prior to age 15, with a peak in the mid 20s. The manifestation of MS, therefore, appears to be dependent upon having passed through the pubertal period suggesting an endocrine influence on the timing of onset of the disease. Since pineal melatonin secretion progressively declines from childhood to puberty and as melatonin exerts an immunomodulating influence, we have proposed that the dramatic decline in melatonin secretion just prior to the onset of the clinical manifestations of puberty may lead to disruption of immune responses resulting in either reactivation of the infective agent or in an increased susceptibility to pubertal or post-pubertal infection. Melatonin secretion undergoes annual rhythms with a zenith in winter and declines to a nadir in the spring. Thus, the fall in melatonin secretion in the spring may account for epidemiological findings revealing a high incidence of relapse of MS in the spring. If the manifestations of MS are related to the fall in melatonin secretion in the post-pubertal period, then one would expect patients with a pubertal onset of the disease to have a higher incidence of relapses in spring than in winter. To test this hypothesis, we investigated in 51 patients the relationship between the seasonal occurrence of the last MS relapse with the age of onset of first manifestation of MS. While 9 of 22 patients (40.9%) who relapsed in spring (March-May) had the onset of MS prior to age 18, only 2 of 29 patients (6.9%) who relapsed in winter (November-February) experienced the onset of first symptoms prior to the age of 18 years (p < .005). These findings thus support the hypothesis implicating the pineal gland and melatonin secretion in the timing of onset of MS. Moreover, the findings may have clinical implications with respect to the prophylaxis of MS relapse in patients who experience seasonally-dependent exacerbation of symptoms.

Epidemiology of multiple sclerosis in U.S. veterans: V. Ancestry and the risk of multiple sclerosis

Self-reported ancestry data for the U.S. population from the 1980 decennial census and multiple sclerosis (MS) risk data derived from a large series of World War II white male veterans with MS and matched controls were aggregated on a state level and analyzed to determine the relationship between ancestry and MS risk. A significant portion of the state-by-state variation in MS risk is explainable statistically by differences in ancestry among state populations, even when geographic latitude is included in analyses. In the main, Swedish and other Scandinavian ancestry is most consistently associated with places with increased MS risk. In some analyses, Italian, French, and (to a lesser extent) Scottish ancestries are also associated with increased risk, whereas English and Dutch ancestries are each associated with decreased risk, but most of these non-Scandinavian correlations may reflect predominantly geography per se. These findings provide evidence that ancestry of the resident population, a confounded measure of genetic susceptibility and cultural environment, is part of the complicated picture of MS as a disease of place.

Multiple sclerosis: the role of puberty and the pineal gland in its pathogenesis

Epidemiological studies demonstrate that the incidence of multiple sclerosis (MS) is age-dependent being rare prior to age 10, unusual prior to age 15, with a peak in the mid 20s. It has been suggested that the manifestation of MS is dependent upon having passed through the pubertal period. In the present communication, I propose that critical changes in pineal melatonin secretion, which occur in temporal relationship to the onset of puberty, are intimately related to the timing of onset of the clinical manifestations of MS. Specifically, it is suggested that the fall in melatonin secretion during the prepubertal period, which may disrupt pineal-mediated immunomodulation, may stimulate either the reactivation of the infective agent or increase the susceptibility to infection during the pubertal period. Similarly, the rapid fall in melatonin secretion just prior to delivery may account for the frequent occurrence of relapse in MS patients during the postpartum period. In contrast, pregnancy, which is associated with high melatonin concentrations, is often accompanied by remission of symptoms. Thus, the presence of high melatonin levels may provide a protective effect, while a decline in melatonin secretion may increase the risk for the development and exacerbation of the disease. The melatonin hypothesis of MS may explain other epidemiological and clinical phenomena associated with the disease such as the low incidence of MS in the black African and American populations, the inverse correlation with sun light and geomagnetic field exposure, the occurrence of relapses in relation to seasonal changes and fluctuations in mood, and the association of MS with affective illness and malignant disease. Therapeutically, this hypothesis implies that application of bright light therapy or the use of other major synchronizers of circadian rhythms such as sleep deprivation or application of external weak magnetic fields may be beneficial in the treatment and/or prophylaxis of relapses in the disease.

Substance P and multiple sclerosis

Multiple sclerosis is an inflammatory disease which affects the white matter of the central nervous system (CNS). The aetiology of this condition is unknown but it is generally believed to represent an autoimmunological response to a component of myelin triggered by an environmental factor, in a genetically susceptible individual. The natural history of the disease, in terms of clinical disability, is unpredictable, and the factors responsible unknown. Substance P is an undecapeptide that acts as a neurotransmitter in the CNS and as a regulator of immune responses. The recent discovery of substance P immunoreactive astrocytes in multiple sclerosis plaques raises the possibility that this peptide may be important both in the development of plaques and in governing the natural history of the disease.