Patients with complaints of poor memory are frequently encountered in clinical practice, but not all of them prove to be truly amnesic when assessed clinically and with objective criteria. Anxiety, hypochondrial worries and depression may hinder the focusing of attention on the event, or task, which the patient is trying to register, and can cause memory gaps that are overemphasized and become the subject of worries. Lapses of attention are also common in patients with organic brain syndromes and may be responsible, along with inadequate encoding strategy, for their poor memory performance. These patients aside, a number of cases remain in which the inability to remember ongoing and past events is the main manifestation of disease and points to the damage of specific anatomical structures. From a clinical perspective, it is important to classify these patients into two groups, depending on whether amnesia appears either in isolation and reflects a focal lesion, or is a component of a more complex pattern of cognitive deficits, consequent to diffuse cortical damage, such as in Alzheimer's disease (see Chapter 7). Although the patients of the latter group are by far the more frequent in clinical practice, it is the former group that has provided the main source of information for delineating the amnesic syndrome and for understanding its anatomico-functional underpinnings.

The amnesic syndrome

Clinical features

Patients with the amnesic syndrome have an unclouded sensorium and appear alert, able to concentrate and are cooperative. Perceptual and intellectual skills are preserved.