A prospective study of reversible dementias: Frequency, causes, clinical profile and results of treatment

Background: Dementia due to potentially reversible etiologies is an important group of dementias to be identified not only because of the number of such Patients encountered but also due to the potential for substantial improvement with treatment.
Aims : To prospectively investigate the frequency and causes of dementias with potentially reversible etiologies; to examine the clinical features of this subgroup with a view to identifying a signature profile and to determine if this potential reversibility translates into actual reversibility with appropriate treatment.
Setting and design : A prospective longitudinal study of patients with dementia presenting to the outpatient services of a tertiary referral hospital.
Methods : All Patients above 40 years referred for evaluation of cognitive complaints were serially enrolled and underwent clinical examination, various laboratory tests and neuroimaging. Patients were followed-up for one year.
Statistical analysis : One way analysis of variance for continuous variables followed by post hoc comparisons using Scheffe′s procedure.
Results: A total of 129 patients met Diagnostic and Statistical Manual of Mental Disorders edition 4 (DSM IV) criteria for dementia and qualified for inclusion into the study. Twenty-four patients (18%), all with moderately severe cognitive [mean mini mental state examination (MMSE) score ± SD = 17.9 ± 4.8] and neuropsychiatric [mean neuropsychiatric inventory (NPI) score ± SD = 30.7 ± 8.7] dysfunction were diagnosed to have reversible causes - neuroinfections in 11 patients, normal pressure hydrocephalus in 8 patients and vitamin B12 deficiency in 5 patients. The majority of these patients had gait and urinary dysfunction reminiscent of subcortical dementias. These reversible causes were clinically suspected in only 58% of patients. In 20/24 patients in whom follow up was possible mean MMSE score had improved to 22.2 and mean NPI score had improved to 8.0, following 6 months of treatment.
Conclusions : Reversible causes, especially neuroinfections and vitamin B12 deficiency accounted for 18% all dementias in this study. The majority of these conditions was not clinically suspected though resulting in moderate to severe cognitive and psychiatric dysfunction. Most of these patients had a subcortical pattern of dementia and showed substantial improvement with treatment.

Keywords
Dementia, reversible causes, neuroinfections, normal pressure hydrocephalus, vitamin B12 deficiency.