A Cochrane review included 10 studies with a total of 711 subjects. All the studies were phase 2 trials. The trials were heterogeneous in terms of types, dosages, routes and frequencies of administration of the adjunctive therapies. Adjunctive drugs included in the studies were peptide T, selegiline (deprenyl), CPI-1189, OPC-14117, valproic acid, thioctic acid, nimodipine, memantine and lexipafant. There were no significant differences between the treated and placebo groups on neuropsychological test scores, number of those that complete the assign dosage of experimental medication, adverse effects, and all-cause mortality, though the adjunctive drugs were well tolerated and safe.
Comment: The quality of evidence is downgraded by inconsistency (heterogeneity in interventions and outcomes).