Prevalence and symptoms of intracranial arachnoid cysts: a population-based study.

To investigate the prevalence of intracranial arachnoid cysts in a large population-based sample. We also aimed to assess the association between arachnoid cysts and cognitive impairment, depression, epilepsy, headache, dizziness, previous head trauma, hip fractures, and mortality. A population-based cohort and nested case-control study. The sample comprised representative populations (n = 1235) aged ≥ 70 years. All participants underwent baseline neuropsychiatric examinations, including computed tomography (CT) of the brain, between 1986 and 2000. All CT scans were examined for arachnoid cysts. Headache, dizziness, history of head trauma, dementia, depression, epilepsy, and hip fracture were assessed using data from clinical examinations, interviews and the Swedish hospital discharge register. Cognition was assessed using the Mini-Mental Status Examination, and depressive symptoms using the Montgomery-Åsberg Depression Rating Scale. Date of death was obtained from the National Swedish Death Registry. The prevalence of arachnoid cysts was 2.3 % (n = 29), with no significant difference between men and women. Probands with and without cysts had the same frequency of headache, dizziness, previous head trauma, cognitive impairment, and depressive symptoms. Furthermore, there were no differences regarding the prevalence of dementia, depression, epilepsy, or previous hip fracture. Arachnoid cysts were not associated with increased mortality. Arachnoid cysts are common incidental finding, with the same rate in men and women, and are probably asymptomatic. The lack of relation with symptoms like headache, dizziness and cognitive impairment suggest caution in ascribing symptoms to incidentally discovered arachnoid cysts and a restrictive attitude to treatment.