Discuss the causes of psychological disturbances in Parkinson’s disease.

In order to address the above the request it is important to define Parkinson’s disease; it’s known causes and main physiological symptoms. Many sufferers of PD experience cognitive and mental dysfunctions from a long list. The causes of such deficits are being debated to a great extent. There is no clear conclusion that states they are caused by chemical changes in the brain associated with PD or if the stressors of living and dealing with a difficult chronic illness cause them. Much research has been undertaken in this area in order to improve our understanding of the causes of these phenomena and lots of new and contradictory results have been found. A discussion of depression in PD will highlight some of these.

Parkinson\'s Disease is defined as a "progressive neurodegenerative disorder" (Factor & Weiner, as cited in Hefti & Weiner, 1988). It is unclear whether there is a genetic or environmental cause. The four symptoms that classically define PD are tremor, rigidity, bradykinesia, and gait and postural abnormalities. The underlying cause of PD seems to be a degeneration of parts of the basal ganglia - specifically, damage to the nigra pars compacta - with a consequent loss of dopaminergic input to the neostriatum and ventral tegmental area of the midbrain (Forno, as cited in Hefti et al, 1988). Motor programs, which allow us to perform automatic actions, are contained within the basal ganglia. Hence, although the brain structures involving motor schema are intact, the lack of the neurotransmitter dopamine causes them to be poorly activated, resulting in the motor deficits described above (Hefti & Weiner, 1988). When around 80 per cent of the cells have died in the substantia nigra the physical symptoms start to appear. So the disease is actually quite advanced when these become apparent.

Schwab & England (1958, as cited in Marsh & Markham, 1973) list a number of psychological disorders they believe to be symptomatic of PD, including changes in personality, depression, agitation, anxiety, confusion, dementia, paranoia and delusions. Due to the paucity of space this essay will concentrate on and discuss the causes of depression in PD. Depression is marked by deep feelings of hopelessness and pessimism; it can be viewed in two ways. Some patients may become demoralized with the diagnosis of PD and experience a ‘reactive depression’. Reactive depressions are linked to external events and are short in duration. Typically the patient experiencing a reactive depression is able to resolve the issue and accept the diagnosis. Individuals experiencing a reactive depression may benefit from supportive psychotherapy (Bunting & Fitzsimmons, 1991). The most typical depression experienced by the patient with PD is endogenous depression. Endogenous depression is caused by a biochemical imbalance in the brain and can be life threatening if not treated.

When James Parkinson (1817, as cited in, Strange) first described, "the shaking palsy," he said, "the senses and intellect remain intact." He did, however, note a high incidence of depression in his case studies, and even some suicidal tendencies. Since then, the incidence of depression in PD has been estimated to be as low as twenty per cent and as high as ninety per cent (Gotham, Brown, & Marsden, 1986) as compared to seven per cent in the general population. The severity of depression in PD is almost always described as mild or moderate (Mayeux, as cited in Heilman & Satz, 1983). There have been many contradictory reports on the specifics of depression in PD, though almost all agreed that degrees of depression were found in PD above the normal rate, there is disagreement as to its cause. Some researchers argue that depression was one of the symptoms of PD, while others claim that depression is a reasonable emotional response to such a disabling condition as PD, and is not specifically a symptom of the disease.

Horn (1974) evaluated patients with PD for depression, and compared their scores to those of a control group of healthy subjects and a group of paraplegics. The aim was to compare the depression present in PD patients with that of a group similarly physically disabled, in order to determine whether PD caused depression beyond that which would be reasonably expected from the degree of physical disability alone. It was found that,