Table 2 Exploratory factor analysis of the Neuropsychiatric Inventory-Questionnaire and factor loadings of the scale items, based on 80% of the randomly split sample (n = 9962). Factor loadings of ≥ 0.40 are highlighted in bold, indicating items which belong to the respective factor. For the purpose of clarity, only factor loadings of ≥ 0.20 are shown in the table

1. Depression—Does the patient seem sad or say that he/she is depressed?

0.739

2. Anxiety—Does the patient become upset when separated from you? Does he/she have any other signs of nervousness such as shortness of breath, sighing, being unable to relax, or feeling excessively tense?

0.515

3. Apathy—Does the patient seem less interested in his/her usual activities or in the activities and plans of others?

0.427

4. Sleep—Does the patient awaken you during the night, rise too early in the morning, or take excessive naps during the day?

0.388

5. Appetite—Has the patient loss or gained weight, or had a change in the type of food he/she likes?

0.237

6. Disinhibition—Does the patient seem to act impulsively, for example, talking to strangers as if he/she knows them, or saying things that may hurt people’s feelings?

0.654

7. Agitation—Is the patient resistive to help from others at times, or hard to handle?

0.652

8. Irritability—Is the patient impatient and cranky? Does he/she have difficulty coping with delays or waiting for planned activities?

0.571

9. Elation—Does the patient appear to feel too good or act excessively happy?

0.368

10. Motor disturbance—Does the patient engage in repetitive activities such as pacing around the house, handling buttons, wrapping string, or doing other things repeatedly?

0.268

11. Hallucinations—Does the patient have hallucinations such as false visions or voices? Does he or she seem to hear or see things that are not present?

0.562

12. Delusions—Does the patient have false beliefs, such as thinking that others are stealing from him/her or planning to harm him/her in some way?

0.490