Understanding Pick Disease, PSP, and CBD: Key Differences, Symptoms, and Diagnosis

By SWA

Introduction

Pick disease, progressive supranuclear palsy (PSP), and corticobasal degeneration (CBD) are all neurodegenerative tauopathies, meaning they involve the abnormal accumulation of tau protein in the brain. These conditions lead to progressive cognitive, behavioral, and motor impairments, but each has distinct clinical, pathological, and diagnostic features.

Since there are no definitive blood tests for these diseases, diagnosis relies on clinical assessment, neuropsychological testing, and brain imaging. Below, we explore each disease in detail, including symptoms, pathology, and diagnostic methods.

1. Pick Disease (A Type of Frontotemporal Dementia - FTD)

Overview

Pick disease is a subtype of frontotemporal dementia (FTD) marked by behavioral, personality, and language changes. It is caused by Pick bodies, abnormal tau protein aggregates that lead to frontal and temporal lobe atrophy.

Key Features

  • Behavioral variant FTD (bvFTD): Disinhibition, apathy, compulsions, and emotional blunting
  • Primary progressive aphasia (PPA): Speech and language deficits
  • Memory is preserved in early stages (unlike Alzheimer’s disease)
  • Brain atrophy mainly affects the frontal and temporal lobes

Pathology

  • Pick bodies: Round, tau-positive inclusions in neurons
  • Severe frontotemporal atrophy ("knife-edge" atrophy)
  • Neuronal loss and gliosis

How to Test for Pick Disease

✅ Clinical Assessment

  • Early behavioral and personality changes
  • Speech and language deficits in some cases

✅ Neuropsychological Testing

  • Executive dysfunction: Poor planning and problem-solving
  • Language testing: Evaluates speech production and comprehension

✅ Brain Imaging (MRI, PET scans)

  • MRI: Frontal and temporal atrophy
  • FDG-PET scan: Hypometabolism in frontal and temporal lobes

✅ CSF or Genetic Testing (if familial FTD suspected)

  • MAPT, GRN, or C9orf72 mutations in some cases
  • Helps rule out Alzheimer’s disease

2. Progressive Supranuclear Palsy (PSP)

Overview

PSP is a parkinsonian syndrome that affects movement, balance, and eye control due to tau protein accumulation in the brainstem and basal ganglia. It progresses faster than Parkinson’s disease and does not respond well to levodopa.

Key Features

  • Frequent falls (early in disease course), especially backward
  • Vertical gaze palsy: Inability to move eyes up and down
  • Bradykinesia and axial rigidity: Stiffness in the trunk and neck
  • Dysphagia and dysarthria: Swallowing and speech difficulties
  • Cognitive dysfunction: Frontal lobe impairment, apathy

Pathology

  • Globose neurofibrillary tangles (tau-positive aggregates)
  • Midbrain atrophy ("hummingbird sign" on MRI)
  • Loss of neurons in the substantia nigra, leading to Parkinson-like symptoms

How to Test for PSP

✅ Clinical Assessment

  • Frequent falls and balance issues
  • Vertical gaze palsy

✅ Neuropsychological Testing

  • Frontal lobe dysfunction: Personality changes, slow thinking

✅ Brain Imaging (MRI, PET scans)

  • MRI: Midbrain atrophy ("hummingbird sign")
  • FDG-PET scan: Reduced metabolism in midbrain and frontal lobes

✅ Dopamine Transporter Scan (DaTscan)

  • Helps distinguish PSP from Parkinson’s disease

3. Corticobasal Degeneration (CBD)

Overview

CBD is a progressive movement and cognitive disorder that often starts asymmetrically. It is characterized by motor dysfunction, apraxia, and the "alien limb phenomenon."

Key Features

  • Asymmetric limb rigidity and dystonia (often starts in one limb)
  • Alien limb phenomenon: Involuntary limb movement
  • Apraxia: Difficulty performing learned movements
  • Cortical sensory deficits: Inability to recognize objects by touch
  • Cognitive impairment develops later in the disease

Pathology

  • Ballooned neurons
  • Tau-positive inclusions in neurons and glial cells
  • Asymmetric atrophy in the cortex and basal ganglia

How to Test for CBD

✅ Clinical Assessment

  • Asymmetric motor symptoms (stiffness, dystonia, or myoclonus)
  • Alien limb phenomenon

✅ Neuropsychological Testing

  • Apraxia and executive dysfunction

✅ Brain Imaging (MRI, PET scans)

  • MRI: Asymmetric cortical and basal ganglia atrophy
  • FDG-PET scan: Hypometabolism in parietal cortex and basal ganglia

✅ CSF or Genetic Testing

  • Rarely used but helps rule out other neurodegenerative diseases

 

Summary

  • Pick disease (FTD): Diagnosed by behavioral/language changes and frontal/temporal atrophy on MRI.
  • PSP: Diagnosed by early falls, vertical gaze palsy, and midbrain atrophy (hummingbird sign) on MRI.
  • CBD: Diagnosed by asymmetric limb dysfunction (alien limb, apraxia) and cortical/basal ganglia atrophy on MRI.

Since these conditions can overlap with Parkinson’s and Alzheimer’s disease, a thorough neurological exam and imaging studies are essential for an accurate diagnosis.

Final Thoughts

While all three disorders are progressive, untreatable, and fatal, understanding their unique clinical and imaging features can aid in earlier diagnosis and better symptom management.

© 2000-2025 Sieglinde W. Alexander. All writings by Sieglinde W. Alexander have a fife year copy right. Library of Congress Card Number: LCN 00-192742 ISBN: 0-9703195-0-9

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