The Increasing Problem of Dementia: Diagnosis and Course

Michael Davidson, Sheba Medical Center, Tel Aviv, Israel

The prevalence of dementia appears to be increasing. Memory function declines with age and older individuals are susceptible to pathologies associated with memory related areas of the brain. It is estimated that worldwide, there are 420 million people over 65 years and the estimated prevalence of dementia in this age group is 7.5%. As the estimated prevalence of dementia in the over 80 age group is 20%, there may be as many as 25 million elderly patients with dementia. The most common diagnosis in dementia is Alzheimer’s disease (AD) at 67%. Common features of this disease are the presence of neurofibrillary tangles and b-amyloid plaques. Behavioral and psychological symptoms that are frequently seen in dementia patients include delusions, hallucinations, agitation, aggression, depressed mood, anxiety, and sleep disturbance. Although these symptoms and behaviors can occur at any stage of the disease, they tend to become more frequent during the middle and late stages of the illness. It has been estimated that up to 90% of elderly patients with dementia manifest one or more of these symptoms at some time during their illness; although the pattern of the different types, and timing of symptom onset varies greatly between patients. Symptoms tend to recur over the course of a dementing disorder, and they become more frequent with increasing disease severity.

Psychosis and agitation are neuropsychiatric symptoms that cause marked caregiver distress and also contribute to patient institutionalization. Psychosis and agitation in AD and related disorders may conceivably reflect both neuropathological and neurochemical alterations. Cholinergic abnormalities appear to contribute to aggression and hallucinations. Specifically, the abundance of neurofibrillary tangles in the neocortex correlates with the presence of psychosis, and the burden of neurofibrillary tangles in the frontal lobes is associated with agitation. The treatment of psychosis and agitation is critical to optimal management of patients with AD and other dementing disorders. The control of psychosis and agitation reduces patient and caregiver distress, and improves the quality of life of both patient and caregiver.