Vascular dementia may be the most common form of dementia in the elderly
Cerebrovascular lesions, mainly lacunes and white matter ischemia, are common in elderly patients with dementia. Vascular dementia (VaD) is the second most common cause of dementia, after Alzheimer's disease (AD). However, lacunar strokes have become an important factor in the clinical expression of AD. Also, population-based studies indicate that vascular risk factors increase the risk of developing AD. It is postulated here that the two main causes of VaD-stroke and ischemic heart disease (IHD)-may be responsible for the majority of cases of dementia in the elderly. STROKE RELATED VaD: Cerebrovascular disease (CVD) is the second leading cause of death worldwide. About 1/3 of stroke survivors [range: 25-41%] 65 years old and above develop VaD within 3 months following the ictus. In the USA alone, 125,000 new cases/year of VaD occur after ischemic stroke (about 1/3 of the 360,000 incident cases of AD). Therefore, more than 1 million elderly people are currently affected by poststroke VaD in the USA. Since current criteria identify "pure" cases of AD and VaD, it is likely that "AD plus CVD" ("mixed" dementia) could be responsible for a large number of cases currently diagnosed as probable AD. CARDIOGENIC VAD: By 2020, IHD leading to congestive heart failure (CHF) will become the leading cause of disability worldwide. Vascular cognitive impairment occurs in 26% of patients discharged from hospitals after treatment for CHF. Cognitive dysfunction correlates with left ventricular dysfunction and systolic blood pressure below 130 mm Hg. CHF is a leading cause of hospital admissions in Western nations (4.5 million cases in the USA alone) and is a growing problem in developing countries. Furthermore, over 800,000 patients/year undergo coronary artery bypass graft (CABG) surgery worldwide, including 300,000 patients in the USA. Measurable cognitive dysfunction occurs post-CABG in 80-90% of patients at hospital discharge. Long-term (5 years) incidence of cognitive defects is 42%. Finally, an international study found short-term postoperative cognitive dysfunction in 26% of patients (>60 years) after abdominal or orthopedic surgery; most of them may be instances of VaD. In conclusion, VaD may be the most underdiagnosed and undertreated form of dementia in the elderly.