Table 2 The onset time of neuropsychiatric symptoms: study characteristics

Craig, 2005 [7]

Probable AD

MMSE: < 10 vs 10–20 vs > 20

Depression and apathy were the earliest to appear, and hallucinations, euphoria, and aberrant motor behavior were the latest symptoms to emerge. Hallucinations were significantly more common in severe dementia (MMSE< 10). Irritability was most prevalent in early disease (MMSE> 20).

Cheng, 2012 [22]

AD

Moderate AD vs mild AD

The prevalence of aberrant motor behavior, delusion, hallucination and sleep disturbance was significantly higher in moderate AD than in mild AD.

Burns, 1990 [23]

AD

Severe AD vs moderate AD

The prevalence of aberrant motor behavior and sexual disinhibition was significantly higher in severe AD than in moderate AD.

Hwang, 2004 [21]

aMCI/ Mild AD

aMCI vs controls; mild AD vs aMCI

There were significant differences in apathy, irritability, anxiety, agitation and abnormal motor behavior between the aMCI and controls. Delusion was significantly increased in mild AD compared to aMCI.

Iulio, 2010 [24]

aMCI/AD

aMCI vs controls;

The prevalence of depression, apathy, agitation and irritability was significantly higher in aMCI than in normal controls.

Ehrenberg, 2018 [25]

AD

Braak I/II, Braak III/IV, Braak V/VI vs controls

In Braak I/II, significantly increased odds were detected for agitation, anxiety, appetite changes, depression, and sleep disturbances, compared to controls. Increased odds of agitation continue into Braak III/IV. Braak V/VI is associated with higher odds for delusions.

Jost, 1996 [6]

AD

Time order

Apathy, depression, sleep disturbance and anxiety appeared before the diagnosis of AD. Irritability and delusions occurred within 5 months after diagnosis; Inappropriate sexual behavior, wandering, agitation within 5–10 months after diagnosis; Hallucination and aggression appear 10 months after diagnosis.

Linde, 2016 [26]

AD

Persistence

Apathy and abnormal behavior showed high persistence; Irritability, agitation, depression and anxiety showed moderate persistence; Delusions, hallucination, appetite changes, and sleep disturbance showed short persistence.