A pilot study examining the impact of lithium treatment and responsiveness on mnemonic discrimination in bipolar disorder

INTRODUCTION

Mnemonic discrimination (MD), the ability to discriminate new stimuli from similar memories, putatively involves dentate gyrus pattern separation. Since lithium may normalize dentate gyrus functioning in lithium-responsive bipolar disorder (BD), we hypothesized that lithium treatment would be associated with better MD in lithium-responsive BD patients.

METHODS

BD patients (N = 69; NResponders = 16 [23 %]) performed the Continuous Visual Memory Test (CVMT), which requires discriminating between novel and previously seen images. Before testing, all patients had prophylactic lithium responsiveness assessed over ≥1 year of therapy (with the Alda Score), although only thirty-eight patients were actively prescribed lithium at time of testing (55 %; 12/16 responders, 26/53 nonresponders). We then used computational modelling to extract patient-specific MD indices. Linear models were used to test how (A) lithium treatment, (B) lithium responsiveness via the continuous Alda score, and (C) their interaction, affected MD.

RESULTS

Superior MD performance was associated with lithium treatment exclusively in lithium-responsive patients (Lithium x AldaScore β = 0.257 [SE 0.078], p = 0.002). Consistent with prior literature, increased age was associated with worse MD (β = -0.03 [SE 0.01], p = 0.005).

LIMITATIONS

Secondary pilot analysis of retrospectively collected data in a cross-sectional design limits generalizability.

CONCLUSION

Our study is the first to examine MD performance in BD. Lithium is associated with better MD performance only in lithium responders, potentially due to lithium's effects on dentate gyrus granule cell excitability. Our results may influence the development of behavioural probes for dentate gyrus neuronal hyperexcitability in BD.

[Public sector psychiatry in Martinique in 1996: handicaps and hopes]

In the light of political, economic and cultural factors the authors give a historical overview of psychiatric practice in the public sector in Martinique (French West Indies) which was for a long time concentrated at the Colson Specialized Medical Center. The evolution of mental health problems is described in parallel with socio-economic changes. Broad opportunities for daily application of psychiatric practice in problematic social situations call forth the notion of "extended psychiatry". A number of changes are now shaping with the creation of diversified decentralized facilities, e.g. in penitentiaries and in some local hospitals. Other projects now being discussed are less certain and there is a risk of a two-speed system between the Specialized Hospital Center and the Regional University Hospital Center. Their authors place hopes in a project covering the whole island in which public sector psychiatry would represent a metacultural model going beyond ideologic handicaps and opening the way to new solidarity.

Auditory brainstem responses and ultrasound changes in a high-risk infants population

50 neonates were selected in a high perinatal risk population and examined by means of cerebral ultrasound (US) and auditory brainstem responses (ABR). They were allocated in 5 groups according to their US diagnosis (normal scans, isolated peri-intraventricular haemorrhage, large haemorrhage with associated lesions, hypoxic-ischaemic lesions in term neonates, miscellaneous disorders). ABR abnormalities were found in 40% of the infants. They were more frequent in neonates with cerebral lesions. Furthermore, the more extensive the cerebral lesions, the more severe the ABR abnormalities. Most of the ABR changes were of audiological type (severe: threshold greater than 80 dB [14%]; moderate: threshold less than or equal to 80 dB [20%]), whereas neurological abnormalities were rare (6%). The prognostic value of ABR appears in this study to depend on the possible recovery in the neonatal period. Severe hearing loss was associated either with an early death or with major handicaps. ABR represent the method of first choice for the detection of hearing loss in the Neonatal Unit, while they seemed to be of limited value in assessing brainstem function.