The influence of immunomodulation on psycho-neuroimmunological functions in benign multiple sclerosis

In multiple sclerosis (MS), several neuroimmunomodulatory effectors are known, including melatonin. They are able to influence disease-related neurophysiogical changes (disability or impaired vision) as well as neuropsychological performance (e.g. cognition and depression). In this study we assessed the relationship between immunomodulation on psycho-neuroimmunological functions in benign multiple sclerosis.

We evaluated 26 young female patients with benign MS treated with/without immunomodulating therapies with regard to their physical disabilities (Expanded Disability Status Scale, EDSS), their visually evoked potentials (VEP), their plasma melatonin concentrations as well as their performance regarding emotional and cognitive tests and compared them with healthy matched controls.

Patients with MS showed deficits in cognitive and emotional functions compared to healthy controls, which were in accordance with their increase in EDSS over time. However, in contrast to untreated patients, patients receiving immunotherapy showed significantly increased dysfunction with respect to actual mood (p = 0.02) and a tendency to increased depression scores (p = 0.072). However, neither treatment subgroup had cognitive deficits. In untreated patients, melatonin levels correlated with reduced scores in the cognitive tests (p = 0.045) but not with depression or VEP latencies. Patients with long-standing MS (>10 years) showed a significant correlation (p = 0.01) to their increased depression scores and their melatonin levels, but no correlation with VEP or cognitive dysfunction, compared to patients with shorter disease duration (< or =10 years).

These results indicate that in MS all aspects of the psycho-neuroimmunological network can be affected. Despite the potential influence of immunomodulation on depression, no connection with melatonin representing the retinohypothalamic tract/pineal gland circuits could be detected. However, visual perception as well as visuoconstructive abilities were affected in MS patients. Neuropsychological tests in MS should concentrate on cognitive variables, which reflect the clinical status more accurately and may be used to monitor disease-modifying therapies.