diff --git a/src/ADNIDatasets.jl b/src/ADNIDatasets.jl
index bd3c987..7d7ed7d 100644
--- a/src/ADNIDatasets.jl
+++ b/src/ADNIDatasets.jl
@@ -15,14 +15,14 @@ struct ADNIScanData
 end
 
 struct ADNISubject
-    ID::Int64
-    n_scans::Int64
+    ID::Int
+    n_scans::Int
     scan_dates::Vector{Date}
     Data::Vector{ADNIScanData}
 end
 
 struct ADNIDataset
-    n_subjects::Int64
+    n_subjects::Int
     SubjectData::Vector{ADNISubject}
     rois::Vector{String}
 end
@@ -209,6 +209,11 @@ function Base.getindex(data::ADNIDataset, idx::Vector{Int})
     return ADNIDataset(length(idx), data.SubjectData[idx], data.rois)
 end
 
+function Base.getindex(data::ADNIDataset, idx::UnitRange{Int})
+    _idx = collect(idx)
+    return ADNIDataset(length(idx), data.SubjectData[_idx], data.rois)
+end
+
 function Base.iterate(d::ADNIDataset, state=1)
     state > length(d) ? nothing : (d[state], state+1)
 end
@@ -221,6 +226,8 @@ function Base.length(data::ADNIDataset)
     get(data, @lens _.n_subjects)
 end
 
+Base.lastindex(d::ADNIDataset) = length(d)
+
 function Base.filter(func, data::ADNIDataset)
     d = Iterators.filter(func, data) |> collect
     ADNIDataset(length(d), d, data.rois)
@@ -237,6 +244,11 @@ function Base.getindex(sub::ADNISubject, idx::Vector{Int})
     return ADNISubject(sub.ID, length(idx), sub.scan_dates[idx], sub.Data[idx])
 end
 
+function Base.getindex(sub::ADNISubject, idx::UnitRange{Int})
+    _idx = collect(idx)
+    return ADNISubject(sub.ID, length(idx), sub.scan_dates[_idx], sub.Data[_idx])
+end
+
 function Base.iterate(d::ADNISubject, state=1)
     state > length(d) ? nothing : (d[state], state+1)
 end
@@ -245,6 +257,8 @@ function Base.length(data::ADNISubject)
     get(data, @lens _.n_scans)
 end
 
+Base.lastindex(d::ADNISubject) = length(d)
+
 # Exports
 export ADNIDataset, ADNISubject, ADNIScanData
 export get_suvr, get_ref_suvr, get_ref_vol, get_vol, get_dates, get_times, 
diff --git a/test/runtests.jl b/test/runtests.jl
index c099b66..ab37afc 100644
--- a/test/runtests.jl
+++ b/test/runtests.jl
@@ -49,10 +49,12 @@ data_scans_2 = ADNIDataset(datadf; min_scans=2, max_scans=2, qc=false)
     @test _idx_subset isa ADNIDataset
     @test get_id.(_idx_subset) == [2, 3]
     @test get_id.(_idx_subset) == get_id.(_filter_subset)
+    @test get_id.(data_scans_1[2:end]) == get_id.(data_scans_1[[2,3]])
 
     # testing indexing of ADNISubject
     @test data_scans_1[2][1] isa ADNIScanData
     @test data_scans_1[2][[1,2]] isa ADNISubject
     @test length(data_scans_1[2][[1,2]]) == 2
     @test data_scans_1[2][[1,2]][1].Date == data_scans_1[2][1].Date
+    @test allequal(get_dates(data_scans_1[2][[2,3]]) .== get_dates(data_scans_1[2][2:end]))
 end
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