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Few studies examined comorbid anxiety and depression's independent association with dementia. We assessed internalizing disorders as risk factors for dementia to avoid pitfalls inherent in separating anxiety and depression. Retrospectively designed prospective comparative cohort study using New Zealand's (NZ) National Minimum Dataset of hospital discharges. Hazards ratios (HRs), estimated from parametric survival models, compared the time to incident dementia after a minimal latency interval of 10 years between those with and without prior diagnosis of an internalizing disorder. A total of 47,932 patients aged 50-54 years were discharged from a publicly funded hospital events in NZ between 1988 and 1992. Of these, 37,631 (79%) met eligibility criteria, and incident dementia was diagnosed in 1594. Rates of incident dementia were higher among patients with an earlier diagnosis of internalizing disorders (572 vs 303 per 100,000 person years at risk (PYAR)). After adjustment for age, sex, ethnicity, and region, those with internalizing disorders were estimated to have a higher risk of developing dementia than those without (adjusted HR = 1.57, 95% CI 1.17-2.10). Females with an earlier diagnosis of internalizing disorders were estimated to have almost twice the risk of developing dementia (adjusted HR 1.80, 95% CI 1.25-2.59). Internalizing disorders affect one in five adults globally. Our findings suggest a significant increase in risk of dementia more than 10 years after the diagnosis of internalizing disorder.

Tetrabenazine (TBZ), a catecholamine-depleting agent initially developed for the treatment of schizophrenia, when tested for other indications, has proven to be more useful for the treatment of a variety of hyperkinetic movement disorders. These disorders include neurological diseases characterized by abnormal involuntary movements such as chorea associated with Huntington's disease, tics in Tourette's syndrome, dyskinesias and dystonias in tardive dyskinesia, also primary dystonias and myoclonus. This review will include and discuss studies published during the period of 1960-2006 regarding the clinical efficacy and tolerability of TBZ in Huntington's disease (HD). It will also review the chemistry, pharmacokinetics and dynamics of the drug and its mechanism of action compared to that of reserpine, the only similar compound. This review emphasizes the advantage of TBZ over dopamine-depleting compounds used in the treatment of chorea and reveals its clinical efficacy and side effects.