["We have previously found that sarcosine, a glycine transporter I inhibitor, can improve the psychiatric symptoms of schizophrenia. In this study, we aimed to investigate whether the agent can also ameliorate neuropsychiatric symptoms of Parkinson's disease (PD) patients with dementia.", 'An 8-week, double-blind, placebo-controlled trial was conducted in patients who had PD with dementia (PD-D). Neuropsychiatric manifestations were measured before and at week 2 (V1), week 4 (V2) and week 8 (V3) after treatment. Linear regression with the generalized estimating equations was applied for data analysis.', "Fifteen patients were randomized into a sarcosine group; the other 15 into a placebo group. The generalized estimating equations model revealed significant differences in Hamilton Depression Rating Scale score (P\u2009=\u20090.049) at V1 and Neuropsychiatry Inventory (P\u2009=\u20090.039) at V2 between the treatment and placebo groups. By excluding the advanced patients from analysis, there were significant differences in Unified Parkinson's Disease Rating Scale V2 (P\u2009=\u20090.004) and V3 (P\u2009=\u20090.040), Hamilton Depression Rating Scale V1 (P\u2009=\u20090.014) and V2 (P\u2009=\u20090.047), Neuropsychiatry Inventory V1 (P\u2009=\u20090.002) and V2 (P\u2009<\u20090.001) and Behavior Pathology in Alzheimer's Disease Rating Scale V2 (P\u2009=\u20090.025) in favor of sarcosine."] Does activation of N-methyl-D-aspartate receptor glycine site temporally ameliorate neuropsychiatric symptoms of Parkinson 's disease with dementia?