Multiple Sclerosis: The Role of the Pineal Gland in its Timing of Onset and Risk of Psychiatric Illness

Abstract

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, therefore, that the clinical manifestation of MS is dependent upon having passed the pubertal period. Since pineal melatonin secretion declines from childhood to puberty and as melatonin is an immunomodulator, we have proposed that the dramatic decline in melatonin secretion just prior to the onset of the physical manifestations of puberty may disrupt immune responses resulting in either reactivation of the infective agent or in an increased susceptibility to post-pubertal infection. The fall in melatonin secretion during pre-puberty may also increase the susceptibility of these patients to affective disorder which is associated with lower melatonin secretion and the presence of a phase-advance of their biological rhythms. We predicted, therefore, a higher incidence of affective disorder in patients with pubertal or post-pubertal onset of MS compared to those in whom the disease manifested later. To test this hypothesis, we studied the incidence of affective disorder in relation to age of onset of first neurological symptoms in 31 MS patients, 6 of whom manifested symptoms of MS prior to age 18 (mean = 16.8 years). All patients with pubertal onset MS and only 48% of the control group had an affective disorder. The pubertal onset patients also had a significantly lower nocturnal melatonin levels and a lower incidence of pineal calcification on CT scan. These findings thus support the hypothesis implicating the pineal gland in the timing of onset of MS and in the risk for the development of affective disorder.

Key Words:

• Multiple sclerosis
• puberty
• pineal gland
• psychiatric illness