A key deficit in<unk>  patients is the inability to correctly copy or draw an image. There are qualitative differences between patients with left hemisphere damage, right hemisphere damage, and Alzheimer's disease. Left hemisphere damage Patients with damage to their left hemisphere tend to preserve items, oversimplify drawing features and omit details when drawing from memory. In addition, left hemisphere patients are less likely to systematically arrange the parts of their drawing. Right hemisphere damage Patients with damage to their right hemisphere have trouble correctly replicating spatial relationships of complex figures. Drawing elements are often piecemeal, transposed to different positions or orientations, or shown diagonally on the page. As a result, right hemisphere patients tend to produce asymmetric or distorted drawings characterized by hemispatial neglect, the omission of elements from one side of the model. It was once thought that right hemisphere patients were twice as likely to make mistakes in 3D construction tasks as left hemisphere patients but this inaccurate conclusion was attributable to participant selection bias in that researchers excluded from studies individuals with severe left hemisphere lesions due to the debilitating language impairments of those individuals. However, included in studies were individuals with severe right hemisphere lesions. Subsequent research has substantiated the absence of a marked difference in performance between left and right hemisphere patients on 3D construction tasks. Alzheimer's disease Alzheimer's disease patients with<unk>  have unique symptoms. Their drawings contain fewer angles, spatial alterations, a lack of perspective and simplifications, which are uncharacteristic of left hemisphere or right hemisphere patients.<unk>  disabilities are present early on in the disease and get progressively worse over time; however even patients with advanced Alzheimer's disease may be able to do some<unk>  tasks. Spontaneous drawing is affected early and is heavily dependent upon semantic memory; therefore simplifications in the drawing may be due to impaired access to semantic knowledge. As Alzheimer's disease progresses, the patient's ability to copy objects becomes increasingly impaired and they may lose the ability to draw correctly a simple figures due to a motor loss in routine memories.
Constructional apraxia
Ideomotor apraxia
Hemimotor neglect
Visuospatial dysgnosia
Neurapraxia
Pseudodyssynergia
Integrative agnosia
Dyssynergia