**3. Comorbidities associated with poststroke depression**

Comorbid conditions prior to a stroke can affect the development of depression after an acute ischemic event. Conditions such as diabetes, and preexisting psychiatric disorders like depression, anxiety, and bipolar disorder can all have an effect on poststroke depression [17, 18]. One meta-analysis has demonstrated that patients that have vascular risk factors such as diabetes are at a higher risk for developing poststroke depression [17]. This is not thought to be related to the vascular depression theory, which will be discussed later in this chapter. In a Chinese study, it was

shown that at 3 months after an acute stroke, patients with diabetes were more likely to develop poststroke depression. This was an independent risk factor for the development of poststroke depression at or after 3 months [17]. The hypothesis behind this is based on the pathophysiology behind both diabetes and poststroke depression, which involves the inflammatory pathway, and the hypothalamic pituitary access. This will be discussed later in the chapter.

Preexisting psychiatric disorders such as depression, anxiety, and bipolar disorder can also predispose patients to worse poststroke depression in the subacute phase, which is within 3 months [17]. One meta-analysis that looked at predictors of poststroke depression found that of the patients that had a preexisting mood disorders such as dysthymia, major depression, minor depression, anxiety, agoraphobia and adjustment disorder were all associated with increased risk of worsening depression after a stroke. Of 1058 patients with reported depression prior to their stroke, 27% had worse depressive symptoms after the acute ischemic event [18]. Premorbid anxiety was also predictive of worsening anxiety after the stroke. Anxiety poststroke results in impaired response to adverse events increased perceived stress and more depressive symptoms [18].
