Gait disorders and depression: common occurrence, bidirectional relationship, and integrated intervention

Up to now, the close association of late-life depression with gait abnormalities is well established (e.g. Soremekum et al., 2010; Brandler et al., 2012; Hughes et al., 2015). Depressive illness belongs to the most common psychiatric disorders in the elderly. It is also one of the most serious (Busch et al., 2013). Depression represents a large amount of global disease burden. Among the elderly population, not only severe depressive symptoms are associated with an increase of suicidal acts, but this also holds true for mild and even subthreshold depressive symptoms (Busch et al., 2013). Gait disorders are also common in the elderly, and their prevalence increases with age. At the age of 60 years, 85% of individuals have a normal gait, but at the age of 85 years or more, this proportion has dropped to nearly 20%. Gait problems in the elderly may lead to the fear of falling, which often ends up in a debilitating development (Sliwka, 2018). This can be characterized by restriction of activity and loss of confidence and mobility, as well as of independence. Subjects with gait disturbances and repeated falls often restrict their sphere of activity and prefer to live safely at home, which may terminate in social isolation or institutionalization (Spanó and Förstl, 1992; Jorstad et al., 2005). Importantly, gait disorders are a marker for future development of cardiovascular disease and dementia (Snijders et al., 2007). These associations suggest that gait problems can reflect an early, preclinical, underlying cerebrovascular or neurodegenerative disease (Verghese et al., 2006). Furthermore, gait disorders with a mixed hypokinetic-rigid and ataxic character are a common occurrence in patients with subcortical arteriosclerotic encephalopathy. Lesions are predominantly found in the putamen, global pallidus, and thalamus or as diffusewhitematter changes (Snijders et al., 2007). In addition, tendency of fall is supposedly increased in patients with white matter changes or ventricular enlargement, findings that have been reported in the elderly individuals who were cognitively impaired or depressed (Masden et al., 1989). Depression in late life alsooccurs in associationwith vascular and neurodegenerative diseases (Thomas, 2004). Cerebrovascular disease predisposes, precipitates,orperpetuates late-lifedepressionby its impacton frontal–subcortical circuits (Sheline, 2003; Herrmann et al., 2008). Magnetic resonance imaging studies in depression have repeatedly demonstrated that signal hypertensities in the white and subcortical gray matter are associated with depressive illness, especially hyperintensities in the deep white matter in the frontal lobes and also in the basal ganglia (Thomas, 2004). The community-based large-sample Rotterdam Scan Studyalso reportedwhitematter changes tobe strongly related to depression (de Groot et al., 2000). In addition, ischemic deep white matter changes show a marked specificity for the white matter at the level of the dorsolateral prefrontal cortex in depression (Thomas et al., 2002). Taken together, these data may also suggest a close pathophysiological link between depression and vascular disease, which may involve the frequently reported abnormalities in the hypothalamic–pituitary–adrenal axis and the immunoinflammatory response in both depression and vascular disease (Thomas, 2004). Chronic inflammation with higher levels of interleukin 6 has been reported to have adverse affective, motor, and neurostructural consequences (Satizabal et al., 2012). In a longitudinal study (Brown et al., 2016), inflammation, depression, and slowing of gait were found to be the defining features for a high-risk mortality phenotype in late life. These study results concerning neurostructural and pathophysiological changes in depression and gait abnormalities open the window to various possiblemechanisms by which depressive symptoms may be linked to gait dysfunction. Vascular mechanisms may be an important joint piece, as it has been reported that there are associations between late-onset depression and gait disturbances with vascular disease such as hypertension or coronary heart disease, frontal–subcortical dysfunction, and whitematter lesions (Brandler et al., 2012). Gait and depressive symptomsmay, therefore, develop due to disruption of neural circuits originating in the prefrontal cortex as a result of neurodegenerative or vascular disease (Tekin and Cummings, 2002). These roughly depicted correlations of gait disorder with late-life depression may serve as a background to understanding the importance of the paper by Choi and colleagues (2019, this International Psychogeriatrics (2020), 32:4, 437–439 © International Psychogeriatric Association 2020