As of November 1, 2008, 4,444 patients with a primary diagnosis of probable AD and 354 patients with a primary diagnosis of DLB were available for analysis. Of these patients, 4,531 (94%) had complete NPI-Q data and served as the basis for the current work. DLB (4.2%) and AD (5.7%) patients did not differ in the proportions of missing NPI-Q data (χ2 = 1.29, p = 0.26, d.f. = 1). However, those with missing NPI-Q data were significantly older (78.8 ± 9.7 vs. 76.1 ± 9.3 years, t = 4.60, p < 0.0001, d.f. = 4,796) and more likely to be women (62.6 vs. 37.5%, χ2 = 6.30, p = 0.01, d.f. = 1). Among those with complete NPI-Q data, there were 4,192 AD (1,810 men and 2,382 women) and 339 DLB (244 men and 95 women) patients, respectively. DLB patients were more likely to be men (72.0% of DLB patients were male, whereas only 43.2% of AD patients were male, χ2 = 104.96, p < 0.0001, d.f. = 1). AD patients were significantly older than DLB patients (76.2 ± 9.4 vs. 74.0 ± 7.8 years, t = 4.20, p < 0.0001, d.f. = 4,529). The presence of NSD was significantly higher among DLB patients relative to probable AD patients (63.1 vs. 26.6%, χ2 = 201.9, d.f. = 1, p < 0.0001).
Table compares patient and informant characteristics for patients with and without NSD by diagnosis. Results suggest that among probable AD patients, those with NSD were more likely to be older and black, whereas among DLB patients, those with NSD were more likely to be male and married. Few other patient or informant characteristics appeared to distinguish diagnostic groups having or not having NSD.
Patient and informant characteristics of the NACC UDS database by diagnosis and NPI-Q-assessed NSD
Differences among centers were apparent. Of the 13 centers reporting 9 or more DLB cases, the presence of NSD ranged from 22.2 to 80.0%. The frequencies of NSD in all centers and their 95% bootstrapped CI are presented in figure and suggest that, along with wide CI among some centers contributing only a small number of cases, there was considerable variation in the presence of NSD in DLB by center, relative to the presence of NSD in AD.
Fig. 1 Proportion of subjects with NPI-Q-assessed NSD by diagnosis and by center. Intervals represent 95% bootstrapped CI and values above each interval correspond to the number of subjects with NSD at the specific center. The total number of subjects with DLB (more ...)
Table examines the extent to which dementia severity and depressive symptoms may have differentiated patients with informant-reported NSD from those without NSD. The CDR SOB was significantly higher in AD patients with informant-reported NSD, but this relationship was not seen in DLB, implying that in AD patients NSD may be a late-stage, rather than early-stage, disease correlate. Higher depression scores were also associated with NSD in AD, but not DLB, patients.
Disease severity and depressive symptoms in relation to NPI-Q-assessed NSD in DLB and AD patients
Informant-reported NSD was also associated with several other key aspects of behavioral disturbance on the NPI-Q, including delusions, hallucinations, agitation and apathy (table ). These informant-reported phenomena were associated with informant-reported NSD in both DLB and AD. It is noteworthy that the comorbidities between these phenomena were higher in DLB, relative to AD patients, implying that such behavioral manifestations are more likely to represent an overlapping, common phenotype in the former, relative to the latter. The nonmotor symptoms of DLB may thus constitute a more recognizable constellation of behaviors than they do in AD, where such phenomena may be more likely to occur in a somewhat more isolated fashion.
Comorbidity of NPI-Q-assessed NSD with hallucinations, delusions, agitation and apathy in DLB and probable AD
The regression summary (OR and 95% CI) is presented in table . Because there were fewer cases missing NPI-Q items relative to missing data with the GDS, we included the NPI-Q depressed mood item in this model. These data suggested that although older age, male gender, black race, CDR SOB, and NPI-Q-derived assessments of depressive symptoms, hallucinations, delusions, agitation and apathy were associated with NSD, the presence of DLB diagnosis was by far the strongest predictor (OR = 2.93, 95% CI = 2.22–3.86). Significant differences were also noted among a few of the centers. Data were virtually identical when cases living alone were excluded (OR for diagnosis = 3.18, 95% CI = 2.39–4.23), suggesting that inclusion of those cases did not influence this association.
Multivariate logistic regression model of predictors of NPI-Q-assessed NSD