D'Arcy L. Little, MD*
Anu Kumar, MD**
*Chief Resident, Family Medicine. Sunnybrook Health Science Centre, North York, Ontario
**Radiology Resident, Mount Sinai Hospital, Toronto, Ontario

As our society ages, dementia increases in prevalence. Although uncommon before age fifty, it is estimated that 10% of those over age 65 years, and up to 40% of those over age 85 years suffer from a type of dementia. Although there are over 70 different causes of dementia, Alzheimer's Disease (AD) is the most common type (See Table 1) . Some conditions that cause dementia can be treated and this can alleviate or occasionally resolve the dementia. As a result, patients with cognitive impairment should undergo appropriate investigation to assess any potential for reversibility.

Alzheimer's Disease is a progressive neurodegenerative disease with characteristic clinical and pathological features. A definitive diagnosis of AD requires the analysis of brain tissue, usually at autopsy, looking for the classic features of cortical atrophy, synaptic and neuronal loss, amyloid angiopathy, neuritic plaques with an amyloid core, neurofibrillary tangles with paired helical filaments, and localized inflammatory reaction. However, the combination of clinical features, and appropriate laboratory and/or radiologic techniques results in a diagnostic accuracy of approximately 80 percent.

Thomas Tsirakis, BA

Late Onset Schizophrenia (LOS) is a rare disorder with a prevalence rate of less than 1 percent within the general population. LOS applies to those individuals who develop schizophrenia after the age of 40. The existence of LOS as a disorder separate from schizophrenia has been wrought with controversy, due mostly to a lack of consensus between European and North American medical standards. The general lack of agreement between the world's medical communities, as well as the overlapping of clinical features between LOS and other psychiatric disorders, has often resulted in misdiagnosis and confusion. In North America, LOS was completely eliminated from the third revised edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IIIR) of the American Psychiatric Association after the release of DSM-IV in 1994, and is now classified utilizing the same criteria as schizophrenia. The European medical community, however, still considers it to be a separate, yet related entity, with its own distinct symptomatology, and continues to define it utilizing DSM-IIIR criteria.

Michele Kohli, BSc

Congestive heart failure (CHF), a clinical syndrome caused by failure of the left or right ventricle, is a leading cause of chronic illness in older persons. In the United States, CHF is the most common cause of hospitalization among those aged 65 years and above. Each year, approximately 400,000 Americans are diagnosed with CHF. Few statistics regarding CHF in Canada have been compiled, but the Heart and Stroke Foundation estimates that 200,000 to 300,000 Canadians have the syndrome. The incidence of CHF appears to be increasing in both Canada and the United States.

An individual's risk of developing CHF increases exponentially as a person ages (See Figure 1), due to age-related changes in the heart structure and function. Physiological and pathological alterations affecting heart rate, preload, afterload and contractile states of the heart reduce cardiac output (See More Fat, Less Specialized Cells in Old Heart). Concurrent changes in the kidney, respiratory and nervous systems may further impair the function of the heart. Congestive heart failure is a syndrome with multiple etiologies.

Early diagnosis of CHF greatly improves the success of treatment.