Multimodal Imaging Group, Research Imaging Centre, Centre for Addiction and Mental Health, (CAMH), University of Toronto, Toronto, Ontario, Canada; Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada.
Cerebral Imaging Centre, Douglas Mental Health University Institute, McGill University, Montreal, Quebec, Canada; Department of Psychiatry, McGill University, Montreal, Quebec, Canada.
Eur Psychiatry. 2019 Sep;61:63-71. doi: 10.1016/j.eurpsy.2019.06.007. Epub 2019 Jul 19.
Impaired illness awareness or insight into illness (IIA) is a common feature of schizophrenia that contributes to medication nonadherence and poor clinical outcomes. Neuroimaging studies suggest IIA may arise from interhemispheric imbalance in frontoparietal regions, particularly in the posterior parietal area (PPA) and the dorsolateral prefrontal cortex (dlPFC). In this pilot study, we examined the effects of transcranial direct current stimulation (tDCS) on brain regions implicated in IIA.
Eleven patients with schizophrenia with IIA (≥3 PANSS G12) and 10 healthy controls were included. A crossover design was employed where all participants received single-session bi-frontal, bi-parietal, and sham stimulation in random order. For each condition, we measured (i) blood oxygen level-dependent (BOLD) response to an illness awareness task pre- and post-stimulation, (ii) regional cerebral blood-flow (rCBF) prior to and during stimulation, and (iii) changes in illness awareness.
At baseline, patients with schizophrenia showed higher BOLD-response to an illness awareness task in the left-PPA compared to healthy controls. Bi-parietal stimulation reduced the interhemispheric imbalance in the PPA compared to sham stimulation. Relatedly, bi-parietal stimulation increased rCBF beneath the anode (21% increase in the right-PPA), but not beneath the cathode (5.6% increase in the left-PPA). Bi-frontal stimulation did not induce changes in rCBF. We found no changes in illness awareness.
Although single-session tDCS did not improve illness awareness, this pilot study provides mechanistic justification for future investigations to determine if multi-session bi-parietal tDCS can induce sustained changes in brain activity in the PPA in association with improved illness awareness.
疾病意识或对疾病的洞察力受损（IIA）是精神分裂症的一个常见特征，导致药物依从性差和临床预后不良。神经影像学研究表明，IIA 可能源于额顶区域的大脑两半球之间的不平衡，特别是在后顶叶区域（PPA）和背外侧前额叶皮质（dlPFC）。在这项初步研究中，我们研究了经颅直流电刺激（tDCS）对与 IIA 相关的脑区的影响。
纳入了 11 名患有 IIA（≥3 PANSS G12）的精神分裂症患者和 10 名健康对照者。采用交叉设计，所有参与者随机接受单次双额、双顶和假刺激。对于每种条件，我们测量了（i）刺激前后对疾病意识任务的血氧水平依赖（BOLD）反应，（ii）刺激前和刺激期间的局部脑血流（rCBF），以及（iii）疾病意识的变化。
在基线时，与健康对照组相比，精神分裂症患者在左 PPA 中对疾病意识任务的 BOLD 反应更高。与假刺激相比，双顶刺激减少了 PPA 中的大脑两半球之间的不平衡。相关地，双顶刺激增加了阳极下方的 rCBF（右侧 PPA 增加 21%），但阴极下方的 rCBF 没有增加（左侧 PPA 增加 5.6%）。双额刺激没有引起 rCBF 的变化。我们没有发现疾病意识的变化。
尽管单次 tDCS 治疗没有改善疾病意识，但这项初步研究为未来的研究提供了机制上的依据，以确定多疗程双顶 tDCS 是否可以在 PPA 中诱导与改善疾病意识相关的大脑活动的持续变化。
