**17. Psychiatric and cognitive disturbances**

Systemic GCs induce dose-dependent a wide range of psychiatric and cognitive disturbances, including memory impairment, agitation, anxiety, fear, hypomania, insomnia, irritability, lethargy, mood lability, and even psychosis [144].

### **17.1. Behavioral effects**

Increase in appetite resulting with weight gain is the most common behavioral side effect of long-term exposure to GCs. Weight gain does not correlate with the cumulative dose. Sleep disturbances are the second most common behavioral side effects of GCs and dose-dependent. The evening dose induces sleeplessness [145, 146].

### **17.2. Psychic effects**

Psychic side effects (PSE) of GCs are quantitatively/qualitatively distinct forms. Symptoms range from an initial slight increase in the overall sense of well-being (independent of improvement in their underlying disease activity) or low-grade mood changes, such as euphoria, grandiosity, emotional lability, depressed or elated mood, up to severe psychiatric disorders, and suicidality. The frequency ranges from 1.3 to 62% in adults. The predicted threshold dose for PSE is ≥20 mg/day of prednisone (or equivalent), but can be seen at very low dosages. PSE commonly develop within the first weeks of exposure, but may occur within few days or at any point during treatment, including withdrawal (especially after long-term and high dose exposures). A family history of depression, previous neuropsychiatric disorders, and alcoholism has also been reported as risk factors for the development of PSE. Women were more likely to develop depression, whereas men were more likely to develop mania. The risk of depression, mania, delirium, confusion, and disorientation increases, but suicidal behavior and panic disorder decreases with age. PSE often disappears shortly after dose reduction or discontinuation. Switching to alternative GCs may be helpful. Clinicians should ask about a prior history of psychiatric disorder and refer patients to a psychiatrist [147–149].

### **17.3. Cognitive effects**

Cognitive impairment is a common, dose-dependent side effect of GCs. Common symptoms are deficits in attention, concentration, memory retention, mental speed, and efficiency. Prolonged exposure to moderate/high doses of GCs may cause cumulative and long-lasting effects on specific brain areas. Low doses of GCs do not affect adult cognitive functions in both short- and long-term exposure. Older patients appear to be more sensitive to memory impairment with short-term exposure [149].
