**5. Nervous system**

Aging results in a reduction in nervous tissue mass, neuronal density and concentration of neurotransmitters. A reduction of central nervous system function in the geriatric patients is observed. Autonomic dysfunction is related with impairment of cardiovascular reflexes, hypotension, arrhythmias and delayed gastric emptying. Temperature regulation is abnormally seen with increasing age. There is an increase in disorders of cognitive function, memory loss, and degenerative diseases such as Parkinson's disease in these patients. Dose requirements of local and anesthetic agents are reduced. Postoperative cognitive dysfunction increases with aging. Geriatric patients are sensitive to centrally acting anticholinergic drugs. Regional anesthesia or combined general and regional anesthesia could be favorable [6].
