Acta Neurologica Belgica (2023) 123:657–659
https://doi.org/10.1007/s13760-022-01937-w
LETTER TO THE EDITOR
Anti‑GAD antibodies associated autoimmunity presenting as isolated
dementia: an expansion of GAD antibody‑spectrum disorders
Rohan R. Mahale1 · Srinath Rajeevan1 · S. Sivaprakash1 · Hansashree Padmanabha1 · Pooja Mailankody1 ·
P. Mathuranath1
Received: 18 February 2022 / Accepted: 20 March 2022 / Published online: 28 March 2022
© The Author(s) under exclusive licence to Belgian Neurological Society 2022
Keywords Glutamic acid decarboxylase · Autoimmunity · Dementia
Dear Sir, occupational and social activities. Two months later, he
became apathetic, not interested in going to his workplace,
Glutamic acid decarboxylase (GAD) is an intracellular not interested in his daily routines. There was no disinhibi-
enzyme involved in the decarboxylation of glutamate to tory behavior, anger outburst, lack of empathy. There was
gamma-aminobutyric acid (GABA). Neurological disorders no difficulty in comprehension, naming objects, object
associated with anti-GAD antibodies (ab) associated autoim- recognition, face recognition, impaired speech, dressing
munity termed as GAD antibody-spectrum disorders include difficulties, tool usage. Factual knowledge was preserved.
stiff-person syndrome (SPS), cerebellar ataxia, temporal He was diagnosed to have diabetes mellitus (DM) at the
lobe epilepsy and limbic encephalitis (LE) [1]. Dementia start of cognitive symptoms. There was no myoclonus,
as the sole neurological manifestation of anti-GAD anti- seizures, psychosis, fluctuation in symptoms, motor weak-
bodies associated autoimmunity is rare. Hereby we report ness, incoordination, sensory symptoms. Family history
a 34-year-old male patient who presented with episodic was unremarkable. Systemic examination did not show any
memory impairment, calculation impairment and apathy abnormalities. Patient was conscious and oriented to time,
of 6 months duration impairing his social and occupational place and person. Montreal cognitive assessment (MOCA)
skills. Brain imaging showed asymmetric right temporal showed impaired visuospatial/executive, memory, atten-
lobe atrophy and 18F-fluorodeoxy glucose-positron emission tion domains. The score was 14/30. Addenbrooke’s cogni-
tomography (FDG-PET) showed bilateral temporal and pari- tive examination III (ACE-III) showed impaired attention,
etal hypometabolism. Serum and cerebrospinal fluid (CSF) memory, fluency and visuo-spatial domains. The score was
GAD antibodies were positive. He had good improvement 56/100. Frontal lobe assessment score was 6/18. The mental
with plasma exchange. status examination showed impaired frontal, bitemporal and
A 34-year-old male, graduate by education, working as right parietal lobes functions. Speech was normal. Fundus
a grocery shop owner, presented with history of memory and cranial nerves examination was normal. Motor, sensory
disturbances of 6 months duration, apathetic behavior for and cerebellar examination with no pyramidal signs. Com-
4 months prior to the hospital visit. Patient developed mem- plete blood counts, renal, hepatic, thyroid functions were
ory disturbances in the form of forgetting recent conversa- normal. Serum vitamin B12, folate, homocysteine levels
tions, recent personal events, recent visitors to his shop. He were normal. Serum autoimmune antibodies and vasculitis
had difficulty in doing financial transactions, money han- profile was negative. Serological tests for syphilis, human
dling in shop, handling grocery items to customers. This immunodeficiency virus was non-reactive. Brain magnetic
was insidious in onset, slowly progressive, impairing his resonance imaging (MRI) showed atrophy in right tempo-
ral lobe with hyperintensities and no contrast enhancement.
18
F FDG-PET MRI brain showed hypometabolism in right
* Rohan R. Mahale
rohanmahale83@gmail.com temporal, bilateral parietal lobes (Fig. 1). The whole body
18
F FDG-PET MRI was negative. CSF analysis showed nor-
1
Department of Neurology, National Institute of Mental mal cell count, protein levels. Serum and CSF GAD anti-
Health & Neurosciences (NIMHANS), Hosur Road, bodies was positive. Patient was treated with intravenous
Bangalore 560029, Karnataka, India
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