Demographic characteristics for the sample are in . The sample was predominantly female (68.1% versus 31.9% male). The mean age was 85.68 (SD=6.62), and participants ranged in age (68 to >89) at the time of dementia diagnosis. Specifically, 20.5% were under the age of 80, 49.2% were between 80 and 89, and 30.3% were over the age of 89. The mean educational attainment for the total sample was 13.27 (SD = 2.92) years and ranged from three years of formal education to doctoral level study, with over half (52.0%) having completed high school. The majority of participants (84.1%) were in the mild stage, 12.2% in the moderate stage, and 3.7% in the severe stage of dementia severity on the CDR. Mean duration of dementia at the time of assessment was 1.94 (SD = 1.31) years and ranged from less than one year to eight years.
Summary of Demographic Characteristics
displays the frequency and severity of behavioral disturbances observed. Over half (51.0%) of participants exhibited at least one NPS, the most common being depression (25.8%). Apathy (18.6%), irritability (17.7%), and delusions (17.3%) were also common. Elation was the least common, reported in fewer than 1% of participants; for this reason it was and excluded from later analyses. Also depicted in are mean severity ratings. Severity of neuropsychiatric symptoms was generally mild, with scores on the 12-point NPI domain scales ranging from 2.00 for hallucinations to 4.52 for apathy.
Frequency and Severity of Neuropsychiatric Symptoms
Among vascular conditions, hypertension was most common, present in 31.3%. Thirteen percent of participants reported a history of hyperlipidemia, while 12.7% reported a history of either heart attack or CABG. Stroke and diabetes were uncommon, with only 10.2% of participants reporting diabetes, and 4.5% reporting a history of stroke. With respect to overall health status, 56.9% of individuals were rated in fair to poor health and 43.1% in good to excellent health.
Chi-square tests revealed significant associations between several vascular variables and individual behavioral disturbances. Stroke was associated with delusions (χ2=6.29, df=1, p=0.01), depression (χ2=5.01, df=1, p=0.03), and apathy (χ2=5.94, df=1, p=0.02). Hypertension was associated with delusions (χ2=7.66, df=1, p=0.006), agitation/aggression (χ2=6.45, df=1, p=0.01), and anxiety (χ2=12.09, df=1, p=0.001). The remaining vascular conditions (diabetes, hyperlipidemia, and heart attack or CABG) were not significantly associated with any NPS. Overall health rating was not significantly associated with any of the behavioral disturbances.
In the logistic models, adjusting for other vascular variables, overall health, dementia severity, and demographic covariates (age, gender, education, and APOE), these associations remained significant. Stroke was associated with a higher risk of apathy (OR=4.48, CI(95)=1.28, 15.61, p=0.02), delusions (OR=4.76, CI(95)=1.33, 17.01, p=0.02) and depression (OR=3.87, CI(95)=1.13, 13.23, p=0.03). Hypertension was associated with greater odds of delusions (OR=2.34, CI(95)=1.16, 4.75, p=0.02), agitation/aggression (OR=2.82, CI(95)=1.24, 6.45, p=0.01), and anxiety (OR=4.10, CI(95)=1.58, 10.00, p=0.002).
Other factors associated with increased risk of NPS were age and dementia severity. Younger age was associated with a 4% to 9% increase in risk for anxiety, apathy, and depression. More severe dementia was associated with delusions (OR=2.21, CI(95)=1.21, 4.02, p=0.01), anxiety (OR=2.50, CI(95)=1.25, 5.01, p=0.008), and disinhibition (OR=3.44, CI(95)=1.56, 7.57, p=0.002). Note, however, that the latter are based on a small number of cases, as the majority of subjects were in the mild stage of dementia severity. Additionally, men were significantly more likely than women to experience disinhibition (OR=2.79, CI(95)=1.29, 13.66, p=0.02). displays the results of the final regression models for the above relationships. Each behavioral disturbance was more likely to occur in the presence of the vascular condition. Presence of APOE E4 allele and education were not associated with any neuropsychiatric symptom. Results of the bivariate regression analyses for relationships that were not significant are depicted in . Note that due to small cell counts, logistic regression procedures could not be performed. In such cases, and Fisher’s Exact tests were conducted.
Relationship of Vascular Risk Factors to Neuropsychiatric Symptoms in Participants with AD
Odds Ratios and 95% Confidence Intervals for Non-Significant Relationships between Vascular Conditions and NPS