Relationship between neuropsychiatric symptoms and cognitive functions in patients with cognitive impairment

Background Cognitive decline and neuropsychiatric symptoms (NPS) are main clinical manifestations in Alzheimer disease (AD). It is unclear whether the link between specific NPS and cognitive domains exists in AD or mild cognitive impairment (MCI). Our study aimed to examine the association between specific cognitive domain and NPS in AD and MCI, and to evaluate whether this association showed variety in different stages of cognitive impairment. Methods A total of 458 patients diagnosed as AD or MCI were included in this study. Neuropsychological batteries were applied in the study. The association between NPS and cognitive function were evaluated by multiple linear regression, and its correlation was evaluated by Spearman correlation coefficient. Results The prevalence of NPS increased with the severity of cognitive impairment, and there were significant differences between MCI and AD. NPS were predominantly associated with cognitive domains, including memory, language, attention, and executive function. Both regression liner analysis and correlation analysis showed delusion, hallucination, and aberrant motor behaviour (AMB) were linked to language and attention. In addition, regression liner analysis illustrated depression, anxiety, and apathy were related to learning and episodic memory. Generally, the delusion, hallucination, and AMB have the broadest impact on cognition. Conclusion Specific NPS was predominantly associated with different cognitive domains. Symptoms of agitation, delusion and irritability indicate worse cognitive performance. Therefore, cognitive improvement should be a therapeutic strategy in managing NPS in AD.