Cognition in advanced normal pressure hydrocephalus: A pilot study from South India

Literature on cognition in normal pressure hydrocephalus (NPH) is sparse and more so on cognition in advanced NPH. To study the cognitive profile in a hospital-based cohort of cognitively-advanced NPH. This was a prospective cross-sectional study. The patients included those availing dementia care service from three different tertiary care centres during a period of 5 years from 2010 to 2014. Patients were considered to have cognitively-advanced NPH if the Addenbrooke's Cognitive Examination(ACE) score was 50 or less. In addition to ACE, the patients underwent a battery of other neuropsychologic tests including the digit forward test, Trail A and Trail B, Rey auditory verbal learning test, Cambridge behaviour inventory, hospital anxiety and depression scale, informant questionnaire for cognitive decline in the elderly, and scale for activities of daily living. Data analysis was done using the Statistical Package for the Social Sciences. Dementia was confirmed in 326 cases, 193 (59.2%) with NPH, 77 (23.6%) with Alzheimer's disease (AD), 29 (8.9%) with frontotemporal dementia (FTD), and 27 (8.3%) with vascular dementia based on the commonly used criteria. Detailed neuropsychologic assessment could be done in 23 patients with NPH and 15 patients with AD. The mean age was 72.06 ± 9.62 years. Thirteen (56.5%) of the patients were males, and the mean duration of education was for 7.74 ± 3.21 years; the mean duration of illness was for 2.73 ± 2.72 years. The mean mini-mental state examination score was 11.6 ± 5.2 and the mean ACE score was 27.26 ± 1.3. The most severely impaired factor was memory (mean score 6.7 ± 4; percentage of maximum score [PMS] 19.41 ± 11.58) and the least affected was language (mean score 15.56 ± 8.25; PMS 37.06 ± 19.63. No significant difference was seen between ACE total score or subscores when the 15 advanced AD patients were compared. The cognitive profile of NPH at an advanced stage was similar to that seen in advanced AD. As advanced NPH shows cognition similar to cortical dementia, the pathologic correlate in NPH may not be hydrocephalus alone.