Clinical Drug Experience Knowledgebase

Promotion of Synaptic Plasticity With D-Aspartate to Favour Recovery Form Cerebral Damage

An important mechanism responsible for clinical recovery after neurological damage of different types is synaptic plasticity. Nervous tissue can enhance or de-energize inter-neuronal transmission at synaptic level in a lasting way. By increasing the efficiency of synaptic transmission, through long-term potentiation (LTP), it is possible to compensate for the loss of synaptic pulses on survived neurons due to brain damage and to restore their function.

At synaptic level, LTP is mainly regulated by NMDA receptors. In animal models induction of plasticity in surviving neurons through the stimulation of NMDA receptors has been shown to limit the clinical manifestations of neuronal damage. Endogenous NMDA is synthesized by methylation of D-aspartate (Asp) by D-aspartatoartate methyltransferase . Moreover, Asp acts as a neurotransmitter capable of activating the NMDA receptor, since its biosynthesis, degradation, absorption and release occurs in the pre-synaptic neuron, and its release determines a response in Post-synaptic neurons. The expression of Asp in the SNC is very abundant during the embryonic period and in early years, whereas it is significantly reduced in adulthood.

Consistent with Asp ability of activating the NMDA receptor, recent studies have shown that oral administration of Asp increases LTP induction in mice. Preliminary studies by our group also showed an increase in LTP amplitude in subjects suffering from progressive forms of Multiple Sclerosis after 2 weeks of daily per os intake of 2660mg Asp.

It is also well known that the therapeutic exercise that characterizes a rehabilitative treatment is able to induce various benefits to the physical-functional and the cognitive-emotional spheres. In this regard, it has been extensively demonstrated how repeatedly performing a motor task can increase cortical excitability through the induction of LTP mechanisms.

Hypothesis Pharmacologically promoting the induction of cortical LTP by the intake of Asp in subjects with various types of brain damage (eg Multiple Sclerosis, Parkinson's Disease, Dementia) may favor the therapeutic effects of rehabilitative treatment.

Specific Objectives A double-blind study to evaluate the effects of D-aspartate in improving the outcome of rehabilitative treatment resulting from brain damage of different origin (eg Multiple Sclerosis, Parkinson's Disease, Dementia). This will be made possible thanks to the specific skills of a multidisciplinary team of neurologists and physiatrists, healthcare professionals such as physiotherapists, occupational therapists, psychologists, speech therapists and the support of a biomedical engineer. These professional figures are already available at the UCK Neurosurgery of the IRCCS Neuromed directed by the proposer and actively collaborate to optimize the therapeutic exercise of patients with neurological damage.

Population of the study This study aims to provide preliminary data on interaction between D-aspartate and therapeutic exercise in inducing LTP cortical phenomena. The sample estimate was made by analogy after a literature analysis. In view of the quite high risk of drop out, our intention is to recruit at least 100 subjects in a population of patients with cerebral injury of various origin, coming to the neurology department of IRRCS Neuromed, Pozzilli.

Inclusion and exclusion criteria are as specified below.

Study design Double-blind prospective study, between randomized, placebo-controlled parallel groups.

Recruited patients will be randomized to receive 2660 mg D-aspartate oral dosing once daily or placebo, in addition to the conventional treatment provided by the relevant staff, for a period of 6 weeks. Patients will also be undergoing a Therapeutic Exercise Program (ET). All conventional therapies taken by patients will be recorded by the operators. Patients will be evaluated at zero time before starting treatment (T-0W) after 6 weeks to evaluate the effects at the end of treatment (T-6W) , and at 12 weeks (T-12W) to evaluate the maintenance of long-term effects. Randomization will be balanced in accordance with age, sex and schooling.

The physiotherapy and/or speech therapy approach will differ among patients considering the different types of brain damage and the different levels of disability, according to the rehabilitation unit team for each case.

Expected results The present study aims to investigate whether the association between pharmacological treatment with D-aspartate and therapeutic exercise may be more effective than just therapeutic exercise in favor of synaptic plasticity and clinical recovery under it, in patients with various forms of brain damage.

The expected result based on previous studies on mice (Errico, 2008, Errico, 2011) is that D-aspartate, promoting neuronal plasticity and acting in synergy with therapeutic exercise, strengthens the recovery of deficits in patients with various types of brain damage.