The articles listed on this page are from a variety of sources. 
1. The staff of DBS-STN often attends conferences or educational opportunities both nationally and internationally, and a brief understandable write-up of the information presented at the event will be provided for our readers to review. 
2. DBS-STN staff also identifies or writes various articles related to topics that are thought to be of interest for the reader of

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Quality of Life - Depression in Parkinson's Patients

The actual incidence of depression among individuals with Parkinson's disease varies widely since different samples (diversity in the research participants), criteria, and methodologies, which includes the variety of scales used to screen for depressive symptoms, have been employed in research studies. For example, research indicating that depression is the predominant emotional difficulty in patients with PD has reported prevalence rates that vary from 2.7 to 90 percent (Ochoa et al., 2003). In recent reported prevalence rates, there is some agreement that about 20 to 40 percent of patient's with PD experience depression serious enough to benefit from intervention (Brooks & Doder, 2001; Poewe & Luginger, 1999). Between 15 and 25 percent of individuals with PD may even present with depression prior to the manifestation of motor symptoms by 1 or more years (Rao et al. 1992; Poewe & Luginger, 1999). There are a few theoretical underpinnings for the experience of depression in individuals with PD whether or not they had DBS surgery. One article eloquently provided three plausible theories for the explanation of depression in PD: 1) Depression is a reaction to stressors of the disease and disability, 2) Depression is a possible result of the PD's medications, and/or 3) Depression is a consequence of the neuroanatomical changes in PD (Edwards et al., 2002). More and more research, however, points to an independent abnormality, rather than solely a maladaptive response to disease, as being a cause of Parkinsonian depression (Poewe & Luginger, 1999; Devinsky & D Esposito, 2004).

Research is just beginning to examine depressive symptoms following DBS-STN surgery. The vast majority of studies we reviewed indicated that DBS-STN patients experience either no change or some improvement in depression following surgery (Ardouin et al., 1999; Bejjani et al., 2000; Morrison et al, 2003; Daniele et al, 2003). This improvement in mood could be attributed to improvement in motor symptoms, improvement in activities of daily living, and the procedure itself may affect the brain systems associated with depression.

It is important to note, however, that a sizable portion of patients show a worsening of depressive symptoms following surgery and depression is sometimes cited as an adverse event (Thobois et al., 2002). One research project studied 24 PD patients prior to and within 6 months postoperatively in mood, motor, and cognitive status to investigate the effects on mood of the DBS-STN (Berney et al., 2002). Their study found that 25% of the patients demonstrated a worsening state of mood, and three were transiently suicidal; this is despite clear motor improvement.

Another study examined 31 patients who underwent DBS-STN surgery and found three patients who became depressed after successful STN surgery and clinical improvement, and one of them attempted suicide (Doshi et al., 2002). Of note, two of these patients had a history of preoperative depression. These two individuals underwent bilateral DBS-STN. After one year, they complained of freezing and walking difficulty, which led to alterations of their electrode combination. Immediately after the alterations, they reported acute depression. "They would break down into tears at the slightest provocation which was different from their preoperative depression" (p.1084). Consequently, they reverted back to their earlier electrode settings, and within 2 days, their symptoms improved. The third patient, who did not have pre-existing depression, complained of symptoms of depression soon after the initial surgery. As reported in the article, the patient stated, "This depression is unusual and uncontrollable for me. I cannot attribute this to any particular event but I cannot help being depressed. I also get an urge to end my life" (p.1084). Although he did attempt suicide, he began medication treatment, and he continues to do well 1 year after surgery.

Another study assessed 24 PD patients postoperatively and found that five patients presented with depression, four of whom had a history of depression before stimulation (Houeto et al., 2002). Specifically, the article provided 5 case illustrations of behavioral and psychiatric changes in these patients. Behavioral and psychiatric changes that were seen in some of these patients included increased mood swings, aggressiveness, irritability, depressed mood, thoughts of suicide, social withdraw, and abnormal sexual behavior. This study made note of one individual who committed suicide before the inclusion period.

The final study illustrates the importance of the stimulator's location in the brain (Bejjani et al., 1999). Moreover, it supports the theory that the placement of the stimulator can induce a clinical presentation of depression. Out of 20 patients treated successfully with bilateral STN stimulation, one woman had transient acute depression when high-frequency stimulation was delivered to a brain structure that is 2 mm below the site where stimulation alleviated the signs of PD. To illustrate the details of the impact that stimulation has on a specific anatomical location, a brief description of the emotional change is as follows: Time 1: The patient looked pleasant while receiving Levadopa, prior to the activation of the brain stimulator. Time 2: Seventeen seconds after stimulation began, the patient showed a change in facial expression. Time 3: Four minutes after stimulation began, the patient began crying and expressing despair. Time 4: One minute and twenty seconds after the stimulation was turned off, the patient was smiling and laughing. Stimulation was repeated twice on two consecutive days to verify the reproducibility of the depressive episode.

When considering depression after DBS-STN, some may plausibly speculate that increased depression after surgery relates to one's expectations about surgery outcome. Specifically, although the surgery is effective in reducing the cardinal motor symptoms of PD, DBS-STN is not a cure, and many patients may feel disappointed and frustrated when symptoms remain and/or complications occur. In addition, the brain systems involved in depression are poorly understood and it is possible that DBS-STN can change brain functioning in ways that may produce or exacerbate depressive symptoms (Thobois, et al., 2002; Houeto et al., 2002; Devinsky & D Esposito, 2004).

In summary, depression and its effect on quality of life in patients with Parkinson's disease is a topic of paramount importance. Future studies can offer a bridge to deepen our understanding of depression in individuals with PD, particularly with regard to the complex journey after DBS-STN. Through our own survey research and reviews of the scientific literature, we hope to provide you with a greater understanding about the prevalence and the impact of depression in the lives of individuals who have undergone DBS-STN.

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