In other cases, depression aggravates dementia, making subtle dementia overt or mild dementia more severe. The patient should be asked about changes in energy, appetite, or sleep that are related to mood disturbances. In the elderly, obsessions are usually due to severe depression, whereas compulsions often result from an obsession. Delusions and Hallucinations Delusions are false, fixed, idiosyncratic ideas. Delusions of poverty or of fatal illness may occur in depressed persons, who may believe that they are behaving badly and that their bad behavior will harm others.
Hallucinations are false visual, auditory, olfactory, or tactile perceptions.
Hallucinations may also occur in persons with sensory deficits, especially profound blindness, at which time the condition is called the Charles Bonnet syndrome. In addition, hallucinations may occur during bereavement, when the patient sees or hears the deceased person. However, cognition is impaired in the alert patient with mental retardation, Alzheimer's disease, or stroke. Attention can be evaluated by asking patients to subtract 7 from 100 and to keep subtracting 7 from each remainder. Patients with little education can be asked to count backward from 20 or to recite the months of the year backward.