In Chapters 1 and 4, we briefly summarized the symptoms of parkinsonism. Parkinsonism implies movement problems that are typical of Parkinson’s disease. They remain treatment issues during the lifetime of people with Parkinson’s disease, even if dementia develops. Similarly, parkinsonism also typically occurs in DLB, although to variable degrees. In these disorders parkinsonism primarily reflects low brain dopamine levels and improves with dopamine replacement therapy, often markedly. Parkinsonism occurs when a region of the brain called the basal ganglia ceases to work properly (see Figure 4.2 in Chapter 4). As discussed in Chapter 4, the substantia nigra is a crucial regulator of basal ganglia activity, which is mediated by dopamine release in the striatum. The substantia nigra degenerates in these Lewy disorders and, as a result, brain dopamine declines. With a decline in dopamine, movement slows. Bradykinesia is the medical term for such slowness. This manifests as not only slowed movement but also less movement and smaller than normal movements. Unconscious automatic movements, such as blinking or arm swing, diminish. A unique tremor of the hands (sometimes legs) often develops when these limbs are in a relaxed position (rest tremor). For unknown reasons, the brain is not affected symmetrically, hence, neither is the body. Typically, one side of the body is much more impaired than the other. The extent to which these symptoms develop differs from person to person and includes various combinations of the following components. The slowness may be apparent on one or both sides of the body. For example, one leg may lag behind when walking. The overall appearance is characterized by moving much slower than expected for one’s age. The person feels as if they are moving in molasses—everything slows down. Many of our daily activities involve repeated small movements, such as writing or brushing teeth. In the Lewy conditions of DLB and PDD, the size (amplitude) of repetitive movements diminishes, impairing the activity. This is exemplified by the small handwriting of someone with parkinsonism, termed micrographia. Clinicians assess repetitive motor function by asking the patient to repetitively tap the thumb and index finger.
Alterations of p11 in brain tissue and peripheral blood leukocytes in Parkinson’s disease