Lithium and prevention of cognitive impairment.

Objective: To examine the rate of cognitive decline and occurrence of dementia among patients attending a lithium clinic for those aged 65 years and over.

Method: Retrospective chart review of the cognitive function of 29 patients receiving maintenance lithium treatment attending the Dublin South East Old Age Psychiatry service, over a nine-year time period.

Results: Twenty-nine patients were included in the study (20 female, nine males), with a mean age of 79 years. Two patients had concurrent dementia. Six patients fulfilled ICD10 criteria for mild cognitive disorder and all of these patients also fulfilled revised consensus criteria for mild cognitive impairment amnestic subtype. Sixteen patients were commenced on lithium as an augmentation treatment for recurrent depressive disorder, 12 patients were on treatment for bipolar affective disorder and one patient on treatment for schizoaffective disorder. Patients had been receiving lithium treatment for an average of 109 months with follow-up by the service for a mean duration of 38 months. The initial mean MMSE score of patients at first presentation to the service was 26.9 (SD = 5.6) compared to a mean MMSE score 25.8 (SD = 5.8) (CI of change in MMSE score at 95% level = -2.1 and 0) at follow-up. The mean MMSE of patients with mild cognitive impairment prior at first contact with the service was 26.8 (SD = 3.2) and at follow-up was 26 (SD = 3.2) which was not statistically significantly different (p=0.40) (CI for change in MMSE at 95% level = -3.2 to 1.5). No patient had developed incident dementia during the follow-up period of the study.

Conclusion: The results tentatively suggest that lithium may have a protective effect against cognitive decline and a neuroprotective role in patients with concurrent affective disorder and cognitive impairment. Multi-centre prospective studies of cognitive function in patients attending lithium clinics are needed to examine the neuroprotective properties of lithium.