Idiopathic normal pressure hydrocephalus (INPH) is a treatable disease of the elderly, typically causing gait impariment, dementia and urinary incontinence. The objective of this study is to make an epidemiological survey of INPH in Umeå, Sweden. Subjects with self-perceived gait impairments will be identified through a questionnaire. They will go through clinical examinations and have an MRI of the brain. A control population will also be investigated to enable comparisons between the populations. The main hypothesis is that the prevalence of INPH in the population is higher than what is previoulsy known.

Inclusion Criteria:

- Living in Umeå, Sweden.

Exclusion Criteria:

• Age <65 or >84 years when the questionnaire was sent out.
• Death at the time for the clinical evaluation.

The number of people, aged 65-84 years and living in Umeå, is approximately 18 000. Of these, 6500 will be randomly selected from the Swedish population registry. They will be asked to answer a mailed-out questionnaire regarding self-perceived gait impairment. Those with self-percieved gait impairment will be invited for clinical examinations as cases and a random selection of those without self-percieved gait impairment will be invited to participate in clinical examinations as controls.