Does subthalamic nucleus stimulation induce apathy in Parkinson’s disease?

Abstract

Although STN-DBS constitutes a therapeutic advance for severely disabled patients with Parkinson's disease, we should keep in mind that this surgical procedure may contribute to the inducing of apathy. Our observation raises the issue of the direct influence of STN- DBS on the limbic system by diffusion of stimulus to the medial limbic compartment of STN.

Apathy in Parkinson's disease: clinical features, neural substrates, diagnosis, and treatment

“…9,99,100 The context in which apathy occurs is crucial to an understanding of underlying mechanisms. A long-term follow-up study 101 showed frequent early but transient apathy occurring in patients in the fi rst postoperative months.…”

“…That is, postoperative apathy is not induced by current diff usion to non-motor territories of the subthalamic nucleus, as had been postulated in the absence of an association between reduction in drug treatment and occurrence of apathy. 100 The only predictive factor for occurrence of apathy during the fi rst year after surgery is the presence of preoperative non-motor fl uctuations. Furthermore, imaging has confi rmed increased mesocorticolimbic denervation in postoperative patients with apathy.…”

Effects of Deep Brain Stimulation on Cognition, Mood and Behaviour in Parkinson’s Disease

“…[30][31][32][33][34] These studies, with few exceptions, 20,[35][36][37][38][39] have observed small and circumscribed cognitive changes, most often in verbal fluency (timed oral word generation according to different phonemic or semantic constraints). 16,17,37,[39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54][55][56][57][58] Even among studies reporting more widespread cognitive declines there is disagreement as to the clinical meaningfulness of these changes. Alegret and co-workers 35 interpreted the changes not to be of clinical significance, in contrast to Saint-Cyr et al 38 and Smeding et al 39 As many of the neuropsychological studies of STN DBS have small sample sizes, greater weight should be given to the five controlled neuropsychological studies (excluding studies limited to language or cognitive screening evaluations), even though each has significant methodological and/or conceptual limitations.…”

“…Stimulation in or around the STN has been observed to acutely lead to visual hallucinations, 64 pseudobulbar crying, 65 laughter and euphoria 4,66 and depression. 67,68 Acute mood changes are typically provoked by stimulation, dorsal or ventral, to the target for motor symptom control, 69 whereas apathy is associated with ventral and medial STN DBS, 55 hypomania with anteromedial STN DBS 70 and delusions with medial stimulation. 71 Aggression occurs with stimulation in the region of the triangle of Sano, 72 although aggression has also been observed after stimulation via accurately placed STN electrodes.…”

“…16,38,74,75 Similarly, studies disagree as to whether apathy does or does not increase after STN DBS. 55,76 On the one hand, studies reporting post-operative incidence of behavioural changes typically do not report a change from the pre-operative state, leaving it possible that the incidence of psychiatric conditions actually improves from pre-operative levels. Indeed, a study has shown that the incidence of psychiatric illness may be greater among PD surgical candidates (before surgery) than among the PD population in general.…”