Multi-infarct dementia (MID), a common form of dementia in the elderly, occurs when blood clots block small blood vessels in the brain and destroy brain tissue. CADASIL (cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy) is an inherited form of MID. This disease can cause stroke, dementia, migraine-like headaches, and psychiatric disturbances. Symptoms of MID, which often develop in a stepwise manner, include confusion, problems with recent memory, wandering or getting lost in familiar places, loss of bladder or bowel control, emotional problems such as laughing or crying inappropriately, difficulty following instructions, and problems handling money. Usually the damage is so slight that the change is noticeable only as a series of small steps. However over time, as more small vessels are blocked, there is a gradual mental decline. The main characteristics of the disorder are:

Impairment in short- and long-term memory.

At least 1 of the following:

Impairment in abstract thinking.
Impaired judgment.
Other disturbances of higher cortical function.
Personality change.

Memory impairment and intellectual impairment caused significant social and occupational impairments.

Absence of occurrence exclusively during the course of Delirium.

Stepwise deteriorating course with "patchy" distribution of deficits.

Focal neurologic signs and symptoms.

Evidence of repeated "strokes".

Associated Features: 

Learning Problem
Dysarthria or Involuntary Movement
Hypoactivity
Psychosis
Depressed Mood
Somatic or Sexual Dysfunction
Hyperactivity
Sexually Deviant Behavior
Odd/Eccentric or Suspicious Personality
Anxious or Fearful or Dependent Personality
Dramatic or Erratic or Antisocial Personality

Differential Diagnosis: 

Some disorders have similar or even overlapping symptoms. The clinician, therefore, in his diagnostic attempt, has to differentiate against the following disorders which need to be ruled out to establish a precise diagnosis.

Normal Process of Aging;
Delirium
Schizophrenia.
Major Depressive Episode
Factitious Disorder with Psychological Symptoms.

Cause:

Serious forgetfulness, mood swings, and other behavior changes are not a normal part of aging. Some of these changes are caused by problems that can be treated or corrected, like a poor diet or lack of sleep. Sometimes too many medicines cause these symptoms in older people. However, Multi-infarct dementia usually affects people between the ages of 60 and 75. Men are slightly more likely than women to have multi-infarct dementia. Multi-infarct dementia is caused by a series of strokes that damage or destroy brain tissue. A stroke occurs when blood cannot get to the brain. A blood clot or fatty deposits, called plaques, can block the vessels that supply blood to the brain, causing a stroke. A stroke also can happen when a blood vessel in the brain bursts. The main causes of strokes are untreated high blood pressure, high blood cholesterol, diabetes, and heart disease. Of these, the most important risk factor for multi-infarct dementia is high blood pressure. It is rare for a person without high blood pressure to develop multi-infarct dementia.

Treatment:

Currently there is no treatment for MID that can reverse the damage that has already occurred. Treatment focuses on prevention of additional brain damage by controlling high blood pressure. Treatment is based on control of symptoms. Other treatments may be advised based on the individual condition.