l-dopa is a chemical which is synthesised in our bodies from an organic amino acid tyrosine, a precursor to a neurotransmitter dopamine. dopa can be also found in mucuna pruriens. L dopa has been used in the past with varying degree of success with Alzheimer's patients. An excess of dopamine can lead to agitation and impulsive behaviour. There is actually a quite good film about l-dopa called 'Awakenings'. Of the caveat with l dopa is carboxylation, that's why it is standard clinical practice to co-administer (with L-DOPA) a peripheral DOPA decarboxylase inhibitor.

Now, it seems to me that said 'dopa-release' therapy is centred around the notion that for best results one will have to get a gradual release of l-dopa in their system.