COGNITION AND ECT

Iannis M. Zervas, M.D.Athens University Medical School

ECT effects on cognitionMemory

Other

ECT effects on memory

Apparent

Real

Apparent effects-positiveMemory improvement (!)

Inaccurate psychologically but crucial from a psychiatric viewpoint

Apparent effects-negativeResidual psychopathology (depression)

Drug effects (psych, anesthesia, other)

New psychosis (young, new onset)

Unmasking of dementia (old)

Subjective complaints (various motives)

Real effectsDisorientation

Anterograde amnesia

Retrograde amnesia

ECTAnterogradeRetrograderecentremote

Time course of memory disturbanceAcute

Subacute

Long-term

ECT effects on non-memory cognitionAcute phase ( 0-7 hours)

General intelligenceno change*Perceptual functionno change*

Attention-left side inattention-reduced speed in vigilance tasks*No change can be attributed to ECT

ECT effects on non-memory cognitionSubacute phase (7-72 hours)

Intelligenceno change or improvedLanguage verbal fluency may be affected

Perceptual/Visuospatial no change Motor function no changeHigher cognitive/ frontal no change

ECT effects on non-memory cognitionMiddle subacute period (72 hrs -1 wk)Intelligence improvement MMSELanguage improvement (rel. to depression)Perceptual improvementAttention/frontal no change (better in reaction time)

ECT effects on non-memory cognitionLate subacute phase (1 wk -7 mo)Intelligenceimproved (or no change due to ECT)Languageno change (due to ECT)Perceptualimproved (normalized depr. changes)Motorimproved ( trend)Attention/frontalimproved mental shifts no change in vigilance

Memory disturbance Acute phase

Postictal

Interictal

Acute memory disturbancePostictal

Acute memory disturbanceInterictal

Subacute memory disturbance

Memory effectsLarge inter-individual variability in:

Severity

Persistence (Reversibility)

Subjective tolerance / discomfort

Factors affecting severity

Number of treatmentsFrequencyStimulus intensity

Electrode placement

WaveformOxygenationMedications

Factors affecting persistenceProlonged post-ictal disorientationPre-ECT cognitive impairment

Probably age, neurological illness (e.g. Parkinsons disease)

other obvious factors never studied ( i.e. substance abuse, medications, cardiac output status, etc)

Attempts to ameliorateNon-pharmacological methods ( schedule, oxygen, electrode placement, etc)

Various pharmacological methods

ECT memory disturbancePharmacological attemptsACTHdexamethasone naloxonevasopressinT4TRHphysostigminecaffeineCa++ channel blockerspiracetampramiracetaminositolergoloid mesylates herbal preparations

Memory systems involved in ECT with related brain structures

Short-term memory or immediate

Verbal

Visual

Neocortex

Long-term memory

Declarative

Learning

Retrieval

Medial temporal Lobe

Diencephalon

Non-Declarative

Priming

Procedural

Striatum/cerebellum

Neocortex

Immediate / short-term memory (working memory)Prefrontal cortex involved; Medial temporal lobe lesions spare this subtypeDysfunctions after course of ECT (patients learn OK but forget fast)Returns to baseline after a few weeksOld patients more sensitive plus difficulty to learn new material. In 6 months no difference with younger.

Declarative memory* New learning (anterograde amnesia)Transitory difficulties in retaining new information and in recognizing or retrieving information learned some time previouslyIncreases with increasing number of treatmentsNot associated with global cognitive dysfunctionRecovers within a few weeks after ECT*conscious recollection of facts and events, autobiographical or public

Declarative memoryRemote memory (Retrograde amnesia)

Deficits in recall of autobiographical facts and events learned before ECTTemporal gradient ( more so for events within the year prior to ECT)Worse with bilateral Worse with sinewave treatmentsReversible by 3 -6 months

Non-declarative memory*

No changeincludes procedural learning ( neostriatum) classical conditioning ( amygdala, cerebellum) perceptual priming (cortical areas)

Implicit memory**No change

*non-conscious recollection of performance **non-conscious ability to learn spatial and temporal data

Neurobiological correlatesTransient disruption of mechanisms for consolidation, retention, maintenanceDisruption of LTP related to persistence of stimuli, specificity /plasticity, associative organization Possibly causes massive long-term induction of potentiation and saturates synaptic strengths obstructing formation of new memoriesTime course of memory disturbance coincides with LTP disruptionRelated to mesial temporal lobe; less affected by bifrontal treatments

Neurochemical correlatesECT inhibits activity of central cholinergic system= decrease in cholinergic transmissionExcessive release of excitatory amino acids and activation of their receptorsKetamine ( NMDA antagonist) may be better alternative for anesthesia

In support ofMedial Temporal Lobe (MTL)Dysfunction in ECT memory disturbance

role of MTL in memorylow seizure threshold in hippocampusLTP disruption (ECS) is a hippocampal process theta activity in left frontal and temporal sites associated with greater retrograde amnesia for autobiographical information

In support of involvement of Prefrontal Cortex (PFC)in ECT memory dysfunctionMost profound physiological effects of ECT found in PFC -reductions in CB, -reductions in metabolic rate, -EEG slow wave activityRetrograde amnesia greater for public events ( PFC) not autobiographical (hippocampus)

Tests of frontal lobe function can co-vary with tests of retrograde amnesia

SUMMARYECT affects selectively memory parameters

There is large inter-individual variability

Memory disturbance is not related to clinical effects on depression

SUMMARY

Memory disturbance is in general reversible

In some cases some retrograde amnesia for sporadic events (public mainly) may persist

Both mesial temporal lobe and prefrontal cortex (lowest seizure threshold in brain) have been implicated in memory trouble

CONCLUSIONOne should keep in mind that for most patients memory improves

Cost-benefit analysis for the patient

Simple measures can contain disturbance

Memory parameters should be monitored systematically - best to acknowledge and support / educate patient and family