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Neuroimaging in Psychiatry [email protected]

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Neuroimaging in Psychiatry [email protected]
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Page 1: Neuroimaging in Psychiatry gm285@cam.ac.uk

Neuroimaging in Psychiatry [email protected]

Page 2: Neuroimaging in Psychiatry gm285@cam.ac.uk

Imaging Modalities •  Molecular Imaging (SPECT, PET) •  MRI (structural, fMRI, DTI, spectroscopy) •  Optical imaging •  EEG, MEG •  None are currently used to diagnose or help

prognosis of individual patients with psychiatric illness.

•  All are useful in research, with group level studies, and some have helped in treatment development

Page 3: Neuroimaging in Psychiatry gm285@cam.ac.uk

Summary points •  PET imaging has helped to establish the most

effective medication dosing strategies •  Imaging could, it is hoped, lead to earlier

diagnoses - eg in Dementia. •  Neuroimaging can help inform our models of

healthy psychology and of psychiatric disorder, and may provide a rational basis for various interventions

Page 4: Neuroimaging in Psychiatry gm285@cam.ac.uk

In-vivo molecular imaging

�The purpose of molecular imaging is to improve understanding of biology and medicine through non-invasive in vivo investigation of cellular molecular events involved in normal and pathologic processes� {Society of Molecular Imaging}

Currently clinical molecular imaging is mainly PET and SPECT!PET!

SPECT!SPECT!

I

O

ON

HO

* *A critical and rate limiting factor is the

development of imaging tracers [probes]!

Page 5: Neuroimaging in Psychiatry gm285@cam.ac.uk

The Techniques: 1. PET

Page 6: Neuroimaging in Psychiatry gm285@cam.ac.uk

SPECT or PET can measure the global pattern of functional loss by mapping blood flow or glucose metabolic rate

Non-selective molecular imaging

Page 7: Neuroimaging in Psychiatry gm285@cam.ac.uk

By use of novel ligands that �bind� to specific molecular targets PET and SPECT can probe more selective abnormalities in patients with AD.

I

O

ON

HO

* *

[R,R]-123I-QNB is a selective ligand that binds with high affinity and selectivity to acetylcholine muscarinic receptors!

Selective molecular imaging:Radiochemistry

Page 8: Neuroimaging in Psychiatry gm285@cam.ac.uk

Dopamine D2 Receptors are Lower in Addiction!

DA

D2

Rec

epto

r Ava

ilabi

lity!

control! addicted!

Cocaine!

Heroin!

Alcohol!

DA!

DA!

DA!

DA! DA !DA !

DA!

Reward Circuits!

DA !DA ! DA !DA !

DA !

Reward Circuits!

DA!

DA!

DA!

DA! DA !

DA!

Drug Abuser!

Non-Drug Abuser!

Page 9: Neuroimaging in Psychiatry gm285@cam.ac.uk

Cause or Consequence of Drug use?

Impulsive rat, liable to addiction

Rat not liable to addiction Dalley et al 2007

Science

Page 10: Neuroimaging in Psychiatry gm285@cam.ac.uk

For most first episode patients, 2mg haloperidol provided 65% D2 occupancy.

Page 11: Neuroimaging in Psychiatry gm285@cam.ac.uk

Effect of amphetamine (0.3 mg/kg) on [123I]IBZM binding in healthy controls and untreated patients with schizophrenia. The y axis shows the percentage decrease in [123I]IBZM binding potential induced by amphetamine, which is a measure of the increased occupancy of D2 receptors by DA following the challenge. Laruelle et al 1996 PNAS

Page 12: Neuroimaging in Psychiatry gm285@cam.ac.uk

Occupancy 2 studies

Page 13: Neuroimaging in Psychiatry gm285@cam.ac.uk

MRI

Page 14: Neuroimaging in Psychiatry gm285@cam.ac.uk

The fore-runner of structural MRI…

Page 15: Neuroimaging in Psychiatry gm285@cam.ac.uk

But take care with confounders

See Ho et al 2011, Lewis et al 2011, Archives of General Psychiatry for discussions

Page 16: Neuroimaging in Psychiatry gm285@cam.ac.uk

Further (clinical) pros and cons of imaging

•  Most treatments involves medicines, and most MRI doesn�t measure chemicals

•  But …

Page 17: Neuroimaging in Psychiatry gm285@cam.ac.uk

How do antidepressants work?

•  By dampening brain activity to negative self-descriptors? – Simplicio, Norbury & Harmer, Molecular

Psychiatry 2012

Page 18: Neuroimaging in Psychiatry gm285@cam.ac.uk
Page 19: Neuroimaging in Psychiatry gm285@cam.ac.uk

Murray, Corlett… Fletcher 2008

Page 20: Neuroimaging in Psychiatry gm285@cam.ac.uk

Amphetamine results similar to psychosis patient results

Page 21: Neuroimaging in Psychiatry gm285@cam.ac.uk

Summary points •  PET imaging has helped to establish the most

effective medication dosing strategies •  Neuroimaging can help inform our models of

healthy psychology and of psychiatric disorder, and may provide a rational basis for various interventions

Page 22: Neuroimaging in Psychiatry gm285@cam.ac.uk

Thanks!

[email protected]


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