Little is known about specific changes of cognitive processing in cluster headache. Studies on event-related potentials (ERP) suggest that stimulus evaluation is impaired in chronic cluster headache and in episodic cluster headache during the cluster period, but not in the interval between two periods. Patients with chronic paroxysmal hemicrania do not show this impairment. Unlike patients with migraine, patients with cluster headache do not present with a loss of cognitive habituation as measured by ERP. In neuropsychologic evaluations, a reversible decline of memory processing was detected during the cluster attack, but not between two attacks. Long-term observation revealed no progressive cognitive decline in cluster headache patients over the years. With regard to personality changes, a liability susceptibility to anxiety disorders and to hypochondriasis, but not to mood changes, has been described inconsistently. All changes in alterations of cognitive processing in cluster headache are demonstrated to be mild and do not relevantly contribute to the clinical picture of this disease.